STUDY MATERIAL FOR B.SC MB BOTANY FOR COMPETITIVE EXAMINATION SEMESTER -IV, ACADEMIC YEAR 2020 - 21

UNIT CONTENT PAGE Nr

I BASICS OF THE PLANT KINGDOM 02

II BASICS OF ANGIOSPERM TAXONOMY 13

III MEDICINAL IMPORTANCE 21

IV BASICS IN PHYSIOLOGY 30

V CELL ORGANELLES GENETICS AND GENETIC ENGINEERING 51

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UNIT - I BASICS OF THE PLANT KINGDOM

BRIEF CLASSIFICATION OF PLANT KINGDOM:

Plant Kingdom – Plantae Kingdom Plantae includes all the plants on the earth. They are multicellular, eukaryotes and consist of a rigid structure that surrounds the cell membrane called the cell wall. Plants also have a green coloured pigment called chlorophyll that is quite important for photosynthesis.

Classification of Kingdom Plantae A plant kingdom is a vast group; therefore, the kingdom is further classified into subgroups. Levels of classification are based on the following three criteria:

1. Plant body: whether the body has well-differentiated structures or not. 2. Vascular system: whether the plant has a vascular system for the transportation of substances or not 3. Seed formation: whether the plant bears flowers and seeds or not; if it does, then whether it is enclosed within fruits or not.

Cryptogams and Phanerogams The plant kingdom has also been classified into two groups ‘cryptogams’ and ‘phanerogams’ based on their seed formation ability.

Cryptogams are plants that do not have well-developed or conspicuous reproductive organs. They have hidden reproductive organs and don’t produce seeds.

Plants that have conspicuous reproductive organs and produce seeds are called phanerogams. Gymnosperms and Angiosperms belong to the group phanerogams.

Considering all these factors, the plant kingdom has been classified into five subgroups. They are as follows: 1. Thallophyta 2. Bryophyta 3. Pteridophyta 4. Gymnosperms 5. Angiosperms

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1. Thallophyta All the plants that lack a well-differentiated body structure belong to the subgroup Thallophyta.

Thallophytes commonly include members with primitive and simple body designs such as green algae and brown algae. The majority of them are aquatic. Common examples are Spirogyra, Chara, Ulothrix, etc.

2. Bryophyta Bryophytes have differentiated plant body like stem, leaf structures. But they lack a vascular system for the transportation of substances across the plant body.

Bryophytes are found in both land and aquatic habitats, hence are known as amphibians of the plant kingdom. Mosses and Marchantia belong to this subgroup.

3. Pteridophyta Pteridophytes have well-differentiated structures such as stem, root, leaves as well as a vascular system. Ferns, horsetails, Marsilea are some common examples of Pteridophytes.

4. Gymnosperms Gymnosperms are plants that have well-differentiated plant body, vascular system and they bear seeds. The term is derived from Greek words, gymno: naked and sperma: seed. The seeds of gymnosperms are naked which means they are not enclosed within a fruit. The perennial, evergreen woody trees belong to this group. Pines, deodar, redwood, etc. are a few examples.

5. Angiosperms Angiosperms are also seed-bearing plants with well-differentiated plant body. The word is derived from Greek words: angio: covered and sperma: seed. Unlike gymnosperms, seeds of angiosperms are enclosed inside the fruits. Angiosperms are commonly known as flowering plants. Examples include the Mango tree, pomegranate plant, etc. Seeds germinate from embryonic leaves called cotyledons. Depending on the number of cotyledons present in seeds, angiosperms are divided into two: monocotyledons or monocots and dicotyledons or dicots.

DIAGNOSTIC FEATURES OF ALGAE Definition: Algae are Eukaryotic, autotrophic and usually aquatic thallophytes. As algae possess chlorophyll, they are photosynthetic in nature. The organization of their thallus is either unicellular or multicellular.

Diagnostic features: ➢ They are usually aquatic. They occur both in marine and freshwater habitats. ➢ Some of the algae are also found as terrestrial, subterranean or epiphytic forms. ➢ The thallus of algae shows great degree of variation in size and form. ➢ The algal cell wall is made up of cellulose.

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➢ They are unicellular or colonial or multicellular unbranched or branched filamentous forms or siphonous forms or heterotrichous forms. ➢ Algal cells have chloroplasts or chromatophores with photosynthetic pigments. ➢ These members show eukaryotic organization but one of the classes Cyanophyaceae has prokaryotic organization. ➢ Algae are autotrophic and synthesize their own food. Their main reserve food material is starch. However, different algae store different food material. ➢ Phaeophyceae stores laminarin or mannitol. ➢ Rhodophyceae stores floridean starch. ➢ Bacillariophyceae and Xanthophyceae stores leucosin. ➢ Algae reproduce by vegetative, sexual and asexual methods. ➢ Sexual reproduction may be isogamous, physiologically anisogamous or oogamous type. ➢ Asexual reproduction takes place by zoospores, aplanospores, endospores, harmagonia and auxospores etc. ➢ Algae show progressive evolution in sexuality. ➢ The motile vegetative cells, zoospores and gametes of algae (except the class Rhodophyceae and Cyanophyacae) show a pair of flagella. Each flagellum shows 9+2 arrangement of fibrils. The flagella of algae are of two types namely acronematic and pantonematic. ➢ Algae exhibit haplontic life cycle or diplontic life cycle, haplodiplontic life cycle, haplobiontic life cycle and diplobiontic life cycle.

ECONOMIC IMPORTANCE OF ALGAE Food: Algae are healthy source of carbohydrates, fats, proteins, and vitamins A, B, C, and E as well as the minerals like iron, potassium, magnesium, calcium, manganese, and zinc. Hence, people of countries like Ireland, Scotland, Sweden, Norway, North and South America, France, Germany, Japan, and China uses it as the food ingredient from the centuries.

Fodder: Algae are also used as the fodder to feed livestock such as cattle and chickens.

Pisciculture: In fish farming, algae plays very important role because it helps in the production process. Fish used plankton and zooplankton as a food. It helps in maintaining the health of the marine ecosystem because algae are naturally absorbent of carbon dioxide and also provide oxygen to the water.

Fertilizer: Algae are rich in minerals and vitamins. So they also used as liquid fertilizer which helps in the repairing level of nitrogen present in the soil.

Reclaiming alkaline: Blue Green Algae helps in the reduction of high concentration of alkalinity in the soil.

Binding agent: Algae act as the binding agents against natural processes such as erosion. Biological indicator:

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Algae are very sensitive. If there is a slight change in the environment their pigments changes or might get died. The water pollution is checked with the help of Algae like Euglena and Chlorella.

DIAGNOSTIC FEATURES OF FUNGI Definition: Fungi are achlorophyllous, heterotrophic, eukaryotic thallophytes. They are non-green in color with the capacity to live in all kinds of environments. They generally feed on dead and decaying organic matter.

General characters of Fungi ➢ Fungi are found in all types of environments where organic materials are available. For examples, water, air, dead and decaying organic matter, living organisms. ➢ Some fungi are unicellular. The thallus of the fungi is long and tubular with filamentous branches called as hyphae. Hyphae are aseptate, coenocytic, uni-, di- or multinucleate. ➢ The mass of interwoven hyphae is called mycelium. Mycelium may be unicellular or multicellular. ➢ The cells of fungi have definite cell wall mainly made up of chitin. Chitin is a nitrogenous material containing polysaccharide. ➢ Fungi are eukaryotic and they do not have plastids. As fungi do not have chlorophyll, they cannot perform photosynthesis. ➢ Fungi live as saprophytes on dead and decaying organic matter, as parasites on/inside living organisms. ➢ The reserve food material of the fungi is glycogen, fats or lipid globules. ➢ Fungi reproduce vegetatively by fragmentation, budding and fission. ➢ During favorable conditions, they reproduce asexually by spores. The asexual spores are called sporangiospores and conidia. The sporangiospores may be zoospores or aplanospores. Zoospores are flagellated spores with one or two flagella. Aplanospores are non-flagellated spores. ➢ Sexual reproduction in fungi is through gametes and is carried out with the help of planogametic copulation, gametangial contact, gametangial copulation, spermatization or somatogamy. ➢ Fungi exhibit asexual haplontic, haplontic-dikaryotic, haplo-diplontic or diplontic life cycle.

ECONOMIC IMPORTANCE OF FUNGI Decomposition and humus formation: Fungi decompose the dead animals and plants. Fungi change them into humus. It plays an important role in germination of plant. It provides important nutrient to plants. Humus also holds the soil particles. Thus, it reduces the chance of soil erosion. Humus also increases the water holding capacity of soil.

Biological succession: Fungi are important part of lichens. Lichens play an important role in biological succession They make barren land suitable for cultivation.

Biological nitrogen fixation:

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Lichens are also involved in biological nitrogen fixation. They fix the atmospheric nitrogen to form nitrates. These nitrates are absorbed by the plants. Some fungi are also involved in free biological nitrogen fixation.

Role of mycorrhizae: Mycorrhizae is an association between fungi and roots of higher plants. It has great survival value for plants. Fungi spread in large area around the plants. It absorbs water and minerals and transports them to plant. Thus, plants can survive in arid conditions.

Commercial cultivation of fungi: Some fungi are edible. They are commercially cultivated in many countries.

Fungi as insecticides: Some fungi attack insects. They kill the insects. For example, fungi are used to kill the wheat bulb flies in USA.

Source of plant hormones: Some fungi are source of plant hormones. Plant hormone gibberellins are obtained from Gibberella.

Wood rotting: Some fungi are involved in wood rotting. These fungi cause rotting of standing trees and lumbers.

Use in baking and brewing industries: Yeasts (Saccharomyces cerevisiae) are used in production of bread and liquor.

Cheese preparation: Pencilliumspecies are used for giving flavour, aroma and characteristic colour to some cheese.

Soya products: Some species of Aspergillus are used for fermenting and producing soya sauce and soya paste from soya beans.

Synthesis is of organic acids: Citric acid is obtained from some Aspergillus species. Some fungi yield fumaric acid and lactic acids.

Source of vitamins and enzymes: Saccharomyces cerevisiae is a source of vitamin B. vitamin D and riboflavin. Some enzymes like diastase. Pectinase also obtained from fungi.

Antibiotics and other drugs: Some fungi are source of antibiotics and other drugs. Eg.Penicillin, Ergotine etc.

DIAGNOSTIC FEATURES OF BRYOPHYTES Definition:

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Bryophytes are chlorophyllous, autotrophic, embryophytic, atracheophytic, archegoniate and amphibious cryptogams which show invariable heteromorphic alternation of generations in their haplodiplontic life cycle. They include liverwort, hornworts and mosses.

General characters of Bryophytes ➢ Bryophytes are primitive land plants that grow on moist shady places. They prefer moist, cool and shady places to grow. ➢ Though they started land life, they require presence of water to complete their life cycle for movement of motile male gametes (antherozoids). ➢ They are predominantly amphibious in nature, hence called “amphibians of the plant kingdom” ➢ Bryophytes show “heteromorphic alternation of generations”. The gametophytic and sporophytic generations alternate with each other regularly in the life cycle. ➢ In primitive bryophytes the gametophyte is dorsoventral, dichotomously branched green prostrate structure. ➢ Bryophytes are autophytes and lead autotrophic mode of nutrition. ➢ Bryophytes lack true roots. In primitive forms there are unicellular rhizoids, while in advanced forms the rhizoids are branched and multicellular. These rhizoids help in anchorage and absorption. ➢ The entire thallus is leaf like in primitive bryophytes while in advanced forms leaves are spirally arranged and are called microphyll. The microphyll is a small leaf with median midrib. ➢ The plant body of bryophytes consists of simple parenchymatous tissue with no vascular tissues like xylem and phloem. ➢ Bryophytes reproduce vegetatively with the help of tubers, bulbils, protonemal branches, fragmentation etc. ➢ Sexual reproduction is oogamous type. The sex organs of bryophytes are called gametangia. Gametangia are multicellular with sterile jacket. Female gametangium is known as archegonium and male gametangium is known as antheridium. ➢ Antheridium is club shaped. It shows a basal stalk and a dome shaped body. ➢ Archegonium is flask shaped. It has a basal small stalk, median swollen venter and a terminal long neck. ➢ Fertilization is possible in the presence of water. The egg is fertilized by the actively swimming motile spermatozoids while it is still within the archegonium. ➢ The fertilized zygote develops into sporophyte. Sporophyte is diploid, multicellular and not well defined. ➢ Life cycle of bryophytes is haplodiplontic with heteromorphic alternation of generation of multicellular generations

ECONOMIC IMPORTANCE OF BRYOPHYTES Ecological importance: The liverworts, mosses and lichens are supposed to be the pioneers in establishing vegetation where other vegetation seems to be practically impossible.

Packing material: Most of the mosses are used as packing material after being dried. They make a fairly good packing material in the case of glass ware and other fragile goods. Especially the dried peat mosses (Sphagnum spp.) are used to pack bulbs, cuttings and seedlings for shipment.

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Used in seed beds: The peat mosses have remarkable power to absorb and hold water like a sponge, they are extensively used in seed beds and green houses to root cutting. The peat mosses (Sphagna) are also used to maintain high soil acidity required by certain plants.

As a source of fuel: The peat is also a potential source of coal. Dried peat may be used as fuel. In Ireland, Scotland and other European countries the peat is used for fuel. In colder parts of the world where peat reaches its greatest development, the lower layers of peat become carbonized, and after the ages have passed, becomes available to humankind in the form of coal.

Absorbent bandages: The Sphagnum plants are slightly antiseptic and possess superior absorptive power. On account of these properties they may be used for filling absorbent bandages in place of cotton, in the hospitals.

As Food: Some Bryophytes e.g., mosses are used as food by chicks, birds and Alaskan reindeer. etc.

DIAGNOSTIC FEATURES OF PTERIDOPHYTES Definition: Pteridophytes are vascular cryptogams. They occupy the position between bryophytes and Spermatophytes. They are chlorophyllous, autotrophic, archegoniate, embryophytic and tracheophytic. Pteridophytes show diplohaplontic life cycle.

General characters of Pteridophytes ➢ These are the first true land plants in the evolution of the plant kingdom. ➢ Pteridophytes exhibit a well-defined heteromorphic alternation of generations. Diploid sporophyte is the dominant phase in life cycle. ➢ Sporophyte is an independent plant and is free from gametophyte at maturity. ➢ Gametophyte is either fully or partially dependent on sporophyte for its nutrition. ➢ Sporophyte is differentiated into stem, root and leaves. ➢ Pteridophytes have an internal conducting system consisting of xylem and phloem. They are the only vascular cryptogams. ➢ The roots of Pteridophytes are adventitious type. ➢ The stem of Pteridophytes is usually a rhizome. ➢ The leaves are small (microphyllous) in several groups of plants and in higher forms they are large (Macrophyllous) and simple with well-developed petiole. ➢ Asexual reproduction is by spores. It may be homosporous (spores produced are of only one type) or heterosporous (spores produced are of two types). ➢ The spores germinate to produce a haploid gametophyte called prothallus. Homosporous species usually produces bisexual (monoecious) gametophytes whereas heterosporous species produce unisexual (dioecious) gametophytes. ➢ The microspore germinates to produce male gametophyte and the megaspore germinates to produce female gametophyte. Gametophyte performs sexual reproduction by zooidogamous type of oogamy ➢ Sex organs (both antheridia and archegonia) are multicellular with a sterile jacket but without stalks

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➢ Fertilization takes place in the venter of archegonium. Water is necessary for it. ➢ The diploid zygote develops into embryo in the archegonial venter. The embryo grows into sporophyte. ➢ The life cycle of Pteridophytes is diplohaplontic with heteromorphic alternation of sporophyte and gametophyte. Sporophyte and gametophyte are independent of each other.

ECONOMIC IMPORTANCE OF PTERIDOPHYTES: Food: Pteridophytes constitute a good source of food to animals. Sporocarps of Marsilea, a water fern, yield starch that is cooked and eaten by certain tribal.

Soil Binding: By their growth pteridophytes bind the soil even along hill slopes. The soil is protected from erosion.

Scouring: Equisetum stems have been used in scouring (cleaning of utensils) and polishing of metals. Equisetum species are, therefore, also called scouring rushes.

Nitrogen Fixation: Azolla (a water fern) has a symbiotic association with nitrogen fixing cyanobacterium Anabaena,Azollae. It is inoculated to paddy fields to function as biofertilizer.

Medicines: An anthelmintic drug is obtained from rhizomes of Dryopteris (Male Shield Fern).

Ornamentals: Ferns are grown as ornamental plants for their delicate and graceful leaves.

DIAGNOSTIC FEATURES OF GYMNOSPERMS Definition Gymnosperms are a group of plants that produce seeds not enclosed within the ovary or fruit.The word “Gymnosperm” comes from the Greek words “gymnos”(naked) and “sperma”(seed), hence known as “Naked seeds.” Gymnosperms are the seed-producing plants, but unlike angiosperms, they produce seeds without fruits. These plants develop on the surface of scales or leaves, or at the end of stalks forming a cone-like structure.

General characters of Gymnosperms 1. They do not produce flowers. 2. Seeds are not formed inside a fruit. They are naked. 3. They are found in colder regions where snowfall occurs. 4. They develop needle-like leaves. 5. They are perennial or woody, forming trees or bushes. 6. They are not differentiated into ovary, style and stigma. 7. Since stigma is absent, they are pollinated directly by the wind. 8. The male gametophytes produce two gametes, but only one of them is functional. 9. They form cones with reproductive structures. 10. The seeds contain endosperm that stores food for the growth and development of the plant.

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11. These plants have vascular tissues which help in transportation of nutrients and water. 12. Xylem does not have vessels, and the phloem has no companion cells and sieve tubes.

ECONOMIC IMPORTANCE OF GYMNOSPERMS As food ➢ Seeds of some species are edible: Cycas, Ginko, Pinus, Gnetum ➢ Stem of Cycas revoluta is a good source of Sago starch ➢ Zamia is a rich source of starch. ➢ Seeds and stem of Cycas revoluta used for making wine.

As medicine ➢ Leaves of Cycas circinalis, Taxus are used as medicines. ➢ Pollen grains of some Cycas have narcotic effect Oil of Juniperus is important. ➢ Ephedrine derived from Ephedra used in treatment of cold, cough. ➢ Anti-cancerous drug called taxol, is obtained from the bark of Taxus

As ornaments ➢ Species of Cycas are used for decoration purposes ➢ Ginkgo bioloba, possess beautiful ornamental leaves ➢ Thuja, Pinus, Taxus etc are grown in parks.

In industry ➢ Spruce or Picea is an important source of pulp wood. ➢ Wood of Juniperus is used in making pencils, scales and holders. ➢ Bark of Larix yields a tannin ➢ Terpentine is obtained from Abiesbalsemea. ➢ Wood of red spruce is especially important for music industry

DIAGNOSTIC FEATURES OF BACTERIA Definition: Bacteria are unicellular organisms belonging to the prokaryotic group where the organisms lack a few organelles and a true nucleus.

General characters: ➢ Bacteria are prokaryotic organisms (Kingdom:Monera) ➢ They do not have cell defined organelles like mitochondria, Golgi bodies, Endoplasmic reticulum.,etc ➢ They are Microscopic, unicellular ➢ They may occur singly or in small groups to form colonies. ➢ They possess rigid cell wall. Cell wall is made up of peptidoglycan (Mureins) and Lipo polysaccharides. ➢ Absence of well-defined nucleus.i.e., DNA is not enclosed in a nuclear membrane. ➢ Ribosomes are scattered in the cytoplasmic matrix and are of 70S type. ➢ The plasma membrane is invaginated to form mesosomes. ➢ Most of the bacteria are heterotrophic. Some bacteria are autotrophic, possess bacteriochlorophyll, ➢ Motile bacteria possess one or more flagella. ➢ The common method of multiplication is binary fission.

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➢ True sexual reproduction is lacking, but genetic recombination occurs by conjugation, transformation and transduction

ECONOMIC IMPORTANCE OF BACTERIA Bacteria as decomposers: Bacteria in soil fix atmospheric nitrogen and ammonia in roots and helps in plants and soil fertility

➢ Nitrifying bacteria –Nitrosomonas, Nitrobacter, Rhizobium &Azotobacter ➢ Ammonifying bacteria

Bacteria are used in food production: Examples: ➢ Soy sauce-Pediococcus ➢ Cheese-Lactobacillus ➢ Vinegar-Acinetobacter

Bacteria are also used in various industries. Examples: Fibre retting- Clostridium felsineum &Clostridium pectinovorum

Industrial production of organic compound- Acrylic acid &Proplene Glycol-Bacillus species

Bacteria in dairy products-Lactic acid bacteria

Bacteria in the production of vitamins: Riboflavin (Vitamin B) -Clostridium butylicum,Cobalamine (Vitamin B12) -Pseudomonas denitrificans

Bacteria in the production of antibiotics ➢ Bacitracin- Bacillus subtilis ➢ Aureomycin – Streptomyces species ➢ Terramycin – Streptomyces rimosus ➢ Streptomycin-Streptomyces griseus

Bacteria in the production of enzymes ➢ Streptokinase-Streptococcus pyogenes ➢ Proteokinase- Bacillus subtilis ➢ Amylase-Bacillus species

Bacteria in the production of Steroids - Cornyebacterium & Streptomyces

DIAGNOSTIC FEATURES OF VIRUS Definition: Viruses are ultra-microscopic, non-cellular living particles, composed solely of a nucleic acid (DNA or RNA) core, surrounded by a protein envelope called capsid.

General characters of Viruses:

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They are non-cellular and very simple in structure, consisting mainly of a nucleic acid surrounded by a protein envelope called capsid. Therefore, a unit of virus is referred to as ‘a virus particle’ rather than ‘a virus cell’.

They are devoid of the sophisticated enzymatic and biosynthetic machinery essential for independent activities of cellular life. Therefore, they can grow only inside suitable living cells.

They are ultra-microscopic and can only be visualized under electron microscope.

They do not increase in size.

They can pass through filters, through which bacteria cannot pass.

A virus is called either ‘DNA virus’ or ‘RNA virus’ depending on whether it contains the nucleic acid DNA or RNA. A virus cannot have both DNA and RNA

ECONOMIC IMPORTANCE OF VIRUS: In preparing antidotes/vaccine: Pox, mumps, polio, jaundice etc diseases can be controlled by penetrating using or dead virus in the human body as vaccines.

In controlling harmful animals and insects: Some animals and insects which are harmful to humans can be controlled by some special virus.

Control of disease: T2 bacteriophage virus saves humans from dysentery by spoiling some harmful bacteria, like, e-coli. In Virotherapy, viruses use as vectors to treat several diseases, as they can explicitly target cells and DNA. It intimates hopeful use in the treatment of cancer and in gene therapy.

In the laboratory: Virus is used in the lab, as the simplest living model. In the research of genetics, the virus is used mostly. It is an important subject in genetic engineering.

In the evidence of evolution: Virus plays a vital role to acquire knowledge about the trend of evolution and the process of formation of living organisms because the virus contains both living and non-Living characteristics.

In nanotechnology, viruses can be considered as organic nanoparticles. Because of their size, shape, and structures have been used as a template for organizing materials on the nanoscale.

In Seawater: A spoon of seawater contains about a million viruses, making them the most plenteous natural substance in aquatic ecosystems. They are useful in the disposal of saltwater and freshwater ecosystems. Viruses increase the number of Photosynthesis in Oceans and are effective for reducing the amount of carbon dioxide in the atmosphere by approximate 3 giga tonnes of carbon per year.

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UNIT - II BASICS OF ANGIOSPERM TAXONOMY

NATURAL SYSTEM OF CLASSIFICATION (BENTHAM AND HOOKER‟S SYSTEM) ➢ It is the natural systems of classification of seed plants were proposed by two British taxonomists George Bentham (1800-1884) and Joseph Dalton Hooker (1817-1911). ➢ They published in Genera Plantarum. ➢ Bentham and Hooker’s system of classification is still used and followed in several herbaria of the world.

Salient Features of Bentham and Hooker’s system: ➢ It is a classification of only the “seed plants” or phanerogams. ➢ They described 97,205 species of seed plants belonging to 7,569 genera of202 families starting from Ranunculaceae up to Gramineae. ➢ They classified all the seed plants into 3 groups or classes i.e. Dicotyledons (165 families), gymnosperms (3 families) and monocotyledons (34 families). ➢ Monocotyledons were described after the dicotyledones. ➢ The dicotyledons were divided into 3 Divisions (Polypetalae, Gamopetalae and Monochlamydeae) and 14 series. Each series again divided into cohorts (modern orders) and cohorts into orders (modern families). ➢ The authors did not mention anything about the origin of the angiosperms. ➢ Creation of the Disciflorae, a taxon not described by the earlier taxonomists. ➢ Among the Monochlamydeae, major taxa, like the series, were divided on the basis of terrestrial and aquatic habits. ➢ Polypetalae carries 82 families, 2610 genera & 31,874 species. Gamopetalae carries 45 families 2619 genera & 34,556 species. Monochlamydae includes 36 families, 801 genera & 11,784 species. Similarly, Monocotyledons consist 34 families, 1495 genera and 18,576 species.

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Merits of Bentham and Hooker’s System: 1. Each plant has been described either from the actual specimen or preserved herbarium sheets so that the descriptions are detailed as well as quite accurate. 2. The system is highly practical and is useful to students of systematic botany for easy identification of species. 3. The flora describes geographical distribution of species and genera. 4. The generic descriptions are complete, accurate and based on direct observations. 5. Larger genera have been divided into sub genera, each with specific number of species. 6. Dicots begin with the order Ranales which are now universally considered as to be the most primitive angiosperms. 7. Placing of monocots after the dicot is again a natural one and according to evolutionary trends. 8. The placing of series disciflorae in between thalami florae and calyciflorae is quite natural. 9. The placing of gamopetalae after polypetalae is justified since union of petalsis considered to be an advanced feature over the free condition. Demerits of Bentham and Hooker’s System: 1. Keeping gymnosperms in between dicots and monocots is anomalous. 2. Subclass monochlamydeae is quite artificial. 3. Placing of monochlamydeae after gamopetalae does not seem to be natural. 4. Some of the closely related species are placed distantly while distant species are placed close to each other.

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5. Certain families of monochlamydeae are closely related to families in polypetalae, e.g. Chenopodiaceae and Caryophyllaceae. 6. Advanced families, such as Orchiadaceae have been considered primitive in this system by placing them in the beginning. Placing of Orchidaceae in the beginning of monocotyledons is unnatural as it is one of the most advanced families of monocots. Similarly, Compositae (Asteraceae) has been placed near the beginning of gamopetalae which is quite unnatural. 7. Liliaceae and Amaryllidaceae were kept apart merely on the basis of characters of ovary though they are very closely related. 8. There were no phylogenetic considerations

PHYLOGENETIC SYSTEM OF CLASSIFICATION (ENGLER AND PRANTL SYSTEM) Classification based on evolutionary features is known as phylogenetic system.

Engler and Prantl (1884-1930): They published detailed classification in 23 volumes of “Die NaturlichenPflanzenfamilien”. They arranged flowering plants according to increasing complexity of their floral morphology. They considered monocot primitive than dicots.

Engler and Prantl are names associated with a system published in 1886.

It is often claimed that this was the first of the phylogenetic systems.

Engler and Prantl’s system is widely followed in Europe and in certain parts of the United States also.

Many herbaria throughout the world arranged their specimens according to the Engler and Prantl sequence.

Engler looked upon the monocots as a primitive group and put them first in the list. So this arrangement starts with monocot families.

Engler's system is more important because it aims to arrange the plants with an evolutionary bias.

In Engler and Prantl, dicotyledons are divided into Archichlamydeae and the sympetalae.

The monochlamydous families were amalgamated with the polypetalae to produce the Archichlamydeae. Sympetale corresponds to Bentham and Hooker’s Gamopetale.

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Among the Archichlamydeae they placed the naked flowers and then passed on to those with sepaloid perianth.

Engler and Prantl’s system totally contained fourteen major divisions. The first thirteen divisions included the algae, fungi, bryophytes and the pteridophytes. The fourteenth division, viz, EmbryophytaSighonogama included both the Gymnosperms and the Angiosperms.

If the system is considered to be phylogenetic. It is to be understood that the monocots are more primitive than the dicots.

The monocots were divided into 11 orders in which the Palmae were elevated into on order.

Dicotyledonae were totally put in 44 orders; 33 in the Archichlamydeae and 11 in the Sympetalae. Curcurbitaceae is elevated to an order (Cucurbitales).

Merits: i. This system of classification is a development over Eichler in many respects. ii. Gymnosperms kept under separate sub-division. iii. It is natural system since its was proposed subsequent to the acceptance of theory of descent. iv. The large artificial group of Bentham and Hooke’s system Monochlamydaceae has been completely abolished. v. Compositae and Orchidaceae treated as most advanced families of dicot and monocots respectively.

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Demerits: I. Monocot treated primitive than dicot. II. Amentiferae and Centrospermae placed at the beginning of Ranales. III. Helobae is placed in between Pandanales and Glumiflorae. IV. Derivation of bi-sexual flower from unisexual. V. Parietal placenta is advanced over axile.

BINOMIAL NOMENCLATURE Definition: Binomial nomenclature is the biological system of naming the organisms in which the name is composed of two terms, where, the first term indicates the genus and the second term indicates the species of the organism.

➢ The system of binomial nomenclature was introduced by Carl Linnaeus. ➢ Multiple local names make it extremely difficult to identify an organism globally and keep a track of the number of species. ➢ Thus, it creates a lot of confusion. To get rid of this confusion, a standard protocol came up. According to it, each and every organism would have one scientific name which would be used by everyone to identify an organism. This process of standardized naming is called as Binomial Nomenclature. ➢ All living species including plants, animals, birds and also some microbes have their own scientific names. ➢ The scientific name of the tiger is presented as Panthera tigris. ‘Panthera’ represents the genus and ‘Tigris’ represents a particular species or specific epithet. ➢ The scientific name of humans is presented as Homo sapiens. ‘Homo’ represents the genus and ‘sapiens’ represents a particular species. ➢ The Indian bullfrog is scientifically written as Rana tigrina. ‘Rana’ is the name of the genus and ‘tigrina’ is the name of the specific species.

Rules of Binomial Nomenclature A Biologist from all over the world follows a uniform set of principles for naming the organisms. There are two international codes which are agreed upon by all the biologists over the entire world for the naming protocol. They are:

➢ International Code of Botanical Nomenclature (ICBN) – Deals with the biological nomenclature for plants. ➢ International Code of Zoological Nomenclature (ICZN) – Deals with the biological nomenclature of animals. ➢ These codes make sure that each organism gets a specific name and that name is globally identified. ➢ The naming follows certain conventions. Each scientific name has two parts: ➢ Generic name ➢ Specific epithet

The rest of the binomial nomenclature rules for writing the scientific names of organisms include the following: 1. All the scientific names of organisms are usually Latin. Hence, they are written in italics. 2. There exist two parts of a name. The first word identifies the genus and the second word identifies the species.

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3. When the names are handwritten, they are underlined or italicized if typed. This is done to specify its Latin origin. 4. The name of the genus starts with a capital letter and the name of the species starts with a small letter.

DRAWBACKS OF BINOMIAL NOMENCLATURE ➢ Some of the basic drawbacks of binomial nomenclature are: ➢ If two or more names are currently in use, according to the law of priority, the correct name will be the one used first, and the others end up being synonyms as validity is the senior synonym. Providing stability in the naming and classification of organisms must be emphasized. ➢ Also, the names used prior to those included in the “SystemaNaturae”, by Linnaeus are not recognized.

ECONOMIC IMPORTANCE OF FABACEAE Fabaceae family has great importance. It is a source of high protein food, oil, and forage. Fabaceae are also used as ornamental plants.

Food: Most of the important pulses belong to this family. These pulses are used as food and are rich in proteins. The common species which give pulses are Gram, Pea, and Kidney bean.

Fodders: Medicago sativa (Alfafa) is one of the best forage crops. Vicia, Melilotus, and Trifolium are also cultivated as the main fodder crops.

Timber: Many plants of the Fabaceae family provide timber of building, furniture, and fuel. The main timber plants are Butea, Dalbergia, etc.,

Vegetable oil: The seed of Arachis hypogea (peanut) is edible. They are also used for the extraction of peanut oil. This peanut oil is hydrogenated and used as vegetable oil.

Dyes: Indigo dyes are obtained from Indigoferatinctoria. The flowers of Butea monosperma give yellow dye.

Medicinal plants: ➢ Many plants of this family are used in medicines. ➢ Glycyrrhiza glabra: It is used for cough and cold. ➢ Clitoriaternatea: is used against snake bite.

Used as weights: The jewelers use the red and white seeds of Abrus precarious as weights called “Ratti”.

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Ornamental plants: Some important ornamental plants are Lathyrus (pea), Lupinus, Clitoria, Butea, etc.

ECONOMIC IMPORTANCE OF CUCURBITACEAE: This family is particularly important economically because its fruits are edible.

Vegetables and fruits: Cucumis melo (Hindi –Kharbuza): The fruits are edible and a number of varieties are known. C. melo var. momordica is Phut and C. melo var. utilissimus is Kakri. Cucumis sativus is Khira.

Citrullus vulgaris (Hindi –Tarbuz): The fruits are large and ripen during summers; it is cultivated on the sandy beds of rivers. C. vulgaris var. fistul osus is Tinda which is used as vegetable.

Cucurbita maxima is Kaddu: Cucurbita maxima is Kaddu while C. pepo is Safed Kaddu; both are used as vegetable.

Benincasaheipida is Petha: Benincasaheipida is Petha. It is used as vegetable; PETHE-KI-MITHAI is also prepared from the fruits.

Lagenaria vulgaris is Lauki: Lagenaria vulgaris is Lauki; the fruit is commonly used as a vegetable. From ripe fruit- shells sitar is made.

Trichosanthesdioca is Parwal: Trichosanthesdioca is Parwal whose fruits are also used in vegetable preparations. T. anguina is Chachinga which is also used as vegetable.

Luffa acutangula is Torai: Luffa acutangula is Torai. This is also a popular vegetable.

Momordica charantia is Karela: Momordica charantia is Karela. The fruits are bitter but used in vegetable preparations. It is said to be useful in gout and rheumatism.

Medicine: There are a few plants also important medicinally. Citrullus colocynthis: Produces the alkaloid colocynthin from its fruits. The fruits and roots are used against snake bite. The alkaloid is also used in other diseases.

Ecballiumelatarium fruits produce elaterium of medicine which has narcotic effect and useful in hydrophobia.

Ornamental: Some plants viz., Ecballium, Sechium, Sicyos are grown in gardens. ECONOMIC IMPORTANCE OF POACEAE

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The family stands first and foremost in respect of economic importance in whole of Angiosperms.

The staple food grains of the population of world are derived from Oryza sativa (Rice) and Triticum aestivum (Wheat). They are cultivated from time immemorial.

The family has been divided on economic basis as follows: Food: Triticum aestivum, Oryza sativa, Zea mays (Maize), Hordeum vulgare (Jaw), Sorghum vulgare (Jowar), Avena sativa (Oats), Pennisetumtyphoides (Bajra) are cultivated for cereals and food grains.

Fooder: Many grasses as Cynodondactylon, Panicum, Cymbopogon, Agrostis, Poa are grown for fodder.

Sugar: Saccharum officinarum (Sugarcane; H. Ganna) is cultivated for gur and sugar.

Building material: Some species of Bambusa e.g. B. tulda, B. vulgaris are used for scaffolding, thatching huts etc.

Furniture: Species of Dendrocalamus (H. Bent), Arundinaria, Melocalamus are used in manufacture of furniture.

Aromatic grasses: Many grasses yield scented oils which are used in perfumery viz. Vetiveriazizanioides (H. Khuskhus) yields vetiver oil from the roots. The roots are also woven into curtains. Andropogonodoratus (Ginger grass), Cymbopogon citratus (Lemon grass), Cymbopogon martini (Geranium grass), Cymbopogon jawarancusa etc. also yield oil.

Medicinal: Phragmites karka, Cymbopogon schoenanthus etc. are medicinal. Secale cereale is cultivated for infection of its inflorescence by Clavicepspurpurea for production of Ergot and for extraction of ergotine. Ergotine is an excellent remedy for uterine contraction.

Paper: It is manufactured from certain species of grasses and bamboos.

Ornamental: Rhynchelytrumrepens, Cortaderiaselloana and some species of the tribe Bambusoideae are ornamentals. Besides these a number of grasses are grown to form fine lawns, play grounds etc.

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UNIT – III MEDICINAL IMPORTANCE

Zingiber officinale (Ginger) Botanical Name of Ginger : ZINGIBER OFFICINALE Roscoe Family of Ginger : ZINGIBERACEAE Parts Used in Ginger : Rhizome

Phytochemicals: The major constituents in ginger rhizomes are carbohydrates (50–70%), lipids (3–8%), terpenes, and phenolic compounds. Terpene components of ginger include zingiberene, β- bisabolene, α-farnesene, β-sesquiphellandrene, and α-curcumene, while phenolic compounds include gingerol, paradols, and shogaol. Besides these, amino acids, raw fiber, ash, protein, phytosterols, vitamins (e.g., nicotinic acid and vitamin A, and minerals are also present

Medicinal importance ➢ It is widely recognized that popular knowledge about the use of medicinal plants in the treatment of several diseases needs to be confirmed. ➢ The traditional use of medicinal plants contributes to the spread of this knowledge and serves as a basis for scientific research seeking evidence of such pharmacological activities ➢ The rhizome is the part that is most used for medicinal purposes. ➢ These folk medicines are generally prepared by maceration and infusion of fresh rhizome, but tinctures, poultices and even the plant in natural are other therapeutic uses. ➢ It is a wide spectrum of traditional uses, as well as biological and pharmacological properties. The cone-shaped flowers are long-lasting and are employed in craft arrangements for ornamental purposes. ➢ The rhizome is used as a tonic and as a stimulant. The rhizome serves as a seasoning in foods, while the floral buds are consumed as vegetables. ➢ The rhizome of ginger has been extensively used with remarkable therapeutic effects for the treatment of inflammation, diarrhoea, stomach cramps, bacterial infections, fever, flatulence, allergies and poisoning. ➢ Powdered rhizome is used to treat ear infections, toothache and, in the form of tea, to treat stomach disease. ➢ The leaves are also used in therapies for joint pain. The juice of cooked rhizome was reported to be effective in combating worms in children. ➢ The creamy substance present in the mature inflorescence, is rich in surfactants and serves as a natural shampoo

Vetiveriazizanioides (Vetiver) Vetiveriazizanioides, commonly known as vetiver is a perennial bunchgrass ofthe family Poaceae, native to India.

Vetiver grows to 150 centimetres (5 ft) high and form clumps as wide.Under favorable conditions, the erect culms can reach 3m in height. The stems are tall and the leaves are long, thin, and rather rigid. The root system of vetiver is finely structured and very strong.

Cultivation:

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Though it originates in India, C. zizanioides is widely cultivated in tropical regions. The major vetiver producers include Haiti, India, Indonesia, and Reunion.

Phytochemical constituents The chemical constituents present in the plant are Vetiverol, Vetivone, Khusimone, Khusimol, Vetivene, Khositone, Terpenes, Benzoic acid,Tripene-4-ol, ß-Humulene, Epizizianal, vetivenylvetivenate, iso khusimol, ß-vetivone, vetivazulene.

In the roots, the main component was valencene (30.36%), while in the shoots and leaves, they were 9-octadecenamide (33.50%), 2,6,10,15,19,23- hexamethyl-2,6,10,14,18,22- tetracosahexaene (27.46%), and 1,2- benzendicarboxylic acid, diisooctyl ester(18.29%).

Medicinal importance: ➢ It is used for boils, burns, epilepsy, fever, scorpion sting, snakebite, and sores in the mouth. ➢ Root extract is used for headache and toothache. ➢ Vetiver oil is regarded as stimulant, diaphoretic and refrigerant. ➢ Local application of leaf paste for rheumatism, lumbago and sprain gives good relief. ➢ he dried roots are also used to perfume the linen clothes. ➢ The rachis is used in the manufacture of moodas, sirkies, etc. ➢ Vetiver has been known in India from the ancient times. ➢ It is known as Khas-Khas and is widely used as cooling agent, tonic and blood purifier. ➢ It is used to treat many skin disorders and is known to have calming effect on the nervous system. ➢ It is regarded as a stimulant, refrigerant and antibacterial and when applied externally, it removes excess heat from the body and gives a cooling effect. ➢ It is used to ringworm, indigestion and loss of appetite. ➢ It has been considered a high-class perfume.

Ocimum sanctum (Tulsi) or Holy basil Ocimum sanctum (Tulsi) is known as the “Queen of plants” which is derived from ‘Sanskrit’, which means "the incomparable one"or“matchless one”.

This plant belongs to the family Lamiaceae which is native throughout the Old-World tropics and cultivated for religious and medicinal purposes.

Phyto Chemicals: Eugenol, cardinene, cubenol, borneol, linoleic acid, linolenic acid, oleic acid, palmitric acid, steric acid, Vallinin, Vicenin, Vitexin, Vllinin acid, Orientin, Circineol, Gallic Acid, vitamin A, vitamin C, phosphrous and iron.

Medicinal importance: Promotes Healthy Heart Holy basil contains vitamin C and antioxidants such as eugenol, which protects the heart from the harmful effects of free radicals. Eugenol also proves useful in reducing cholesterol levels in the blood.

Anti-aging

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Vitamin C and A, phytonutrients, in Holy Basil are great antioxidants and protect the skin from almost all the damages caused by free radicals.

Treats Kidney Stones Tulsi acts a mild diuretic & detoxifying agent which helps in lowering the uric acid levels in the body. Acetic acid present in holy basil helps in the breakdown of the stones.

Relieves Headaches Tulsi is a natural headache reliever which can also relieve migraine pain.

Fights Acne Holy basil helps kill bacteria and infections. The primary active compound of holy basil oil is eugenol which helps fight skin related disorders. Ocimum Sanctum helps treat skin infections both internally and externally.

Relives Fever Tulsi is an age-old ingredient for treating fever. It is one of the prime ingredients in the formulation of various ayurvedic medicines & home remedies.

Eye Health Tulsi's anti-inflammatory properties help promote eye health by preventing viral, bacterial and fungal infections. It also soothes eye inflammation and reduces stress.

Oral Health Tulsi is a natural mouth freshener and an oral disinfectant. Ocimum Sanctum can also cure mouth ulcers. Holy basil destroys the bacteria that are responsible for dental cavities, plaque, tartar, and bad breath, while also protecting the teeth.

Cures Respiratory Disorders Due to the presence of compounds like camphene, eugenol, and cineole, tulsi cures viral, bacterial, and fungal infections of the respiratory system. It can cure various respiratory disorders like bronchitis & tuberculosis.

Rich Source of Vitamin K Vitamin K is an essential fat-soluble vitamin that plays an important role in bone health and heart health.

Azadirachtaindica (Neem) Family:Meliaceae A large branched evergreen tree growing in fallow lands. It is also cultivated as an avenue and roadside tree in almost every corner of the country. The tree is kept in high esteem in Indian mythology.

Medicinal importance: Neem is considered a boon for mankind by nature. Use of Neem has been recommended by Ayurveda for a wide range of diseases. Such usage are attributed to its purification effect on blood. Scientific research on Neem demonstrates it to be a Panacea. It is suggested to be an antibacterial, anthelmintic, antiviral, anticancer and more importantly Immunomodulatory agent.

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Chemical Composition Neem plant contains flavonoids kemferol, quercetin and myricetin. The trunk bark contains nimbin, nimbinin, nimbosterol, tannins and a bitter principle margosine.

There are numerous benefits and uses of neem leaves as follows: Treats Acne Neem has an anti-inflammatory property which helps reduces acne. Azadirachta Indica also helps reduce skin blemishes.

Nourishes Skin Neem is a rich source of Vitamin E which help repair damaged skin cells.

Treats Fungal Infections Neem has scientifically proven antifungal property which helps treat fungal infections.

Useful in Detoxification Neem can prove useful in detoxification both internally and externally. Consumption of neem leaves or powder stimulates kidneys and liver increasing the metabolism and eliminating the toxins out of the body. Externally, neem scrubs or paste can be used to remove germs, bacteria, dirt, etc from your skin preventing rashes and skin diseases.

Increases Immunity Neem is known for its antimicrobial and antibacterial effects. These properties play a huge role in boosting immunity.

Insect & Mosquito Repellent You can burn a few neem leaves to ward off the insects. This is also effective against different types of mosquitoes . From all the home remedies for malaria , neem is the best for treating the early symptoms of malaria.

Prevents Gastrointestinal Diseases Neem's anti-inflammatory properties help reduce inflammation of the gastrointestinal tract which helps reduce a series of diseases like constipation, stomach ulcer, flatulence, etc. Try out these home remedies for constipation.

Treats Wounds Neem leaves have an antiseptic property which is why it is used to heal wounds.

Reduces Dandruff Neem is extensively used in shampoos and conditioners. Azadirachtaindica has antifungal and antibacterial properties which help eliminate dandruff and strengths your hair.

Reduces Joint Pain Application of neem oil or extract on the affected area can help reduce pain and discomfort. Hence it is widely used for treating arthritis. Exfoliates skin Neem is an excellent exfoliant. It helps remove dead cells from the surface of the skin which will help prevent the growth of blemishes.

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Solanum trilobatum (Thuthuvalai) Solanum trilobatum is a thorny, much branched, straggling shrub or climbing plant with stems that are usually slightly woody at the base. It belongs to the family of Solanaceae. It distributed in Southeast Asia - India, Myanmar, Thailand, Vietnam, Malaysia. The plant is often found as a garden weed within its native range.

Phytochemicals: Phytochemical screening of this plant extract proved the presence of major bioactive drugs such as sobatum, solasodine, tomatidine, disogenin and solaine in various parts of the plant.

Medicinal importance: ➢ The bitter roots and young shoots have been given in the form of an electuary, a decoction or a powder for consumption. ➢ The medicine is mainly used for asthma, chronic febrile affections and difficult parturition ➢ The plant is antibacterial, antifungal, antimitotic, antioxidant and antitumour. ➢ It is used in the treatment of asthma; vomiting of blood; rheumatism; several kinds of leprosy; to help reduce blood glucose levels, bilious matter and phlegm ➢ The leaf juice is drunk as a remedy for fever ➢ The seeds are used as a vermifuge ➢ An extract of the leaves has shown good antimicrobial activity against both gram- positive and gram-negative bacteria

Phyllanthus emblica (Nellikai) or Amla or Indian gooseberry Phyllanthus emblica belonging to the family Euphorbiaceae, are widely distributed throughout most tropical and subtropical countries. It is native to tropical south eastern Asia and found in mixed forest of tropical and sub-tropical regions at altitude of 150–1400 m. The fruit of P. emblica is one of the important and most widely used herbal drugs

Phytochemicals Ascorbic acid (vitamin C) is the most abundant constituents of P. emblica fruit. Linolenic, linoleic, oleic, stearic, palmitic and myristic acids. Emblicanin A and Emblicanin B, pedunculagin and punigluconin are the major tannins reported from this plant. β-sitosterol, emblicol, gibberellins, glutamic acid, glycine, histidine, isoleucine, kaempferol, leucodelphinidin, methionine, phenylalanine, phyllantidine, phyllemblic acid, quercetin, riboflavin, rutin.

Medicinal importance: Healing options ➢ Amla protects cells against free radical damage and provides antioxidant protection ➢ Amla is used to treat skin disorders, respiratory infections, and premature aging ➢ Amla is useful in hemorrhage, diarrhea, dysentery, and has therapeutic value in treating diabetes. ➢ Amla has antibacterial and astringent properties that help to prevent infection and help in the healing of ulcers ➢ Amla is sometimes used as a laxative to relieve constipation in piles.

Immunity booster

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It is used as energy-promoting, disease-preventing tonic may be its effect on the immune system.

Respiratory disorders Indian gooseberry is beneficial in the treatment of respiratory disorders. It is especially valuable in tuberculosis of lungs asthma and bronchitis.

Diabetes It has high Vitamin C content, is effective in controlling diabetes. It will also prevent eye complication in diabetes.

Heart disorder: Indian gooseberry is considered an effective remedy for heart disease. It tones up the functions of all the organs of the body and builds up health by destroying the heterogeneous or harmful and disease causes elements. It also renews energy.

Eye disorder: The juice of Indian gooseberry with honey is useful in preserving eyesight. It is beneficial in the treatment of conjunctivitis and glaucoma. It reduces intraocular tension in a remarkable manner. Juice mixed with honey can be taken twice daily for this condition.

Aging Indian gooseberry has revitalizing effects, as it contains an element which is very valuable in preventing aging and in maintaining strength in old age. It improves body resistance and protects the body against infection. It strengthens the heart, hair, and different gland in the body.

Amla/treats hypertension Amla is rich in Vitamin C and helps control blood pressure.

Natural cure for anemia Amla is rich in Vitamin C or ascorbic acid, an essential ingredient that helps in the absorption of Iron. Supplements of amla can be very beneficial to patients suffering from Iron deficiency Anemia.

Antioxidant Nature has gifted us with defensive antioxidant mechanisms-superoxide dismutase, catalase, glutathione (GSH), GSH peroxidases, reductase, Vitamin E (tocopherols and tocotrienols), Vitamin C, etc., along with several dietary components.

Enhances food absorption The regular use of Amla-Berry can strengthen digestion, absorption, and assimilation of food. Balances stomach acids It improves digestion but does not heat the body; Amla-Berry is ideal for calming mild to moderate hyperacidity and other pitta-related digestive problems.

Diarrhea

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It is used medicinally for the treatment of diarrhea. As a fruit decoction, it is mixed with sour milk and given by the natives in cases of dysentery.

Scurvy As an extremely rich source of Vitamin C, Indian gooseberry is one of the best remedies for scurvy. Powder of the dry herb, mixed with an equal quantity of sugar, can be taken in doses of one teaspoon, thrice daily with milk.

Andrographis paniculata (Nilavembu) It belongs to the family of Acantheceae. A. paniculata is an erect annual herb native to India, China, and Southeast Asia and widely cultivated in Asia. The plant grows 30 to 110 cm in height. It is native to South Asian countries such as India and Sri Lanka.

Phytochemicals: The plant contains bitter glucosides: andrographolide, panaculoside, flavonoids, andrographonin, panicalin, neoandrographolide, apigenin 7‐4‐dimethyl ether. β-sitosterol glucoside, bitter substances, myristic acids, carcrol, neoandrographolide, chlorogenic, pan icolide,eugenol,caffeic,hentriacontane,

Medicinal uses: ➢ Andrographis is frequently used for preventing and treating the common cold and flu (influenza). ➢ Some people claim andrographis stopped the 1919 flu epidemic in India, although this has not been proven. ➢ Andrographis is also used for a wide assortment of other conditions. ➢ It is used for digestive complaints including diarrhea, constipation, intestinal gas, colic, and stomach pain; for liver conditions including an enlarged liver, jaundice, and liver damage due to medications; for infections including leprosy, pneumonia, tuberculosis, gonorrhea, syphilis, malaria, cholera, leptospirosis, rabies, sinusitis, and HIV/AIDS; and for skin conditions including wounds, ulcers and itchiness. ➢ Some people use andrographis for sore throat, coughs, swollen tonsils, bronchitis, and allergies. ➢ It is also used for “hardening of the arteries” (atherosclerosis), and prevention of heart disease and diabetes. ➢ Other uses include treatment of snake and insect bites, loss of appetite, kidney problems (pyelonephritis), hemorrhoids, and an inherited condition called familial Mediterranean fever. ➢ Andrographis is also used as astringent, bacteria killing agent, painkiller, fever reducer, and treatment for worms.

Acalyphaindica (Kuppaimeni) Indian nettle is an annual to sometimes short-lived perennial herb that usually grows up to 1.5 metres tall with occasional specimens to 2.5 metres. It belongs to the family Euphorbiaceae. Distribution range Africa - Senegal to Somalia, south to S. Africa; E. Asia - Indian subcontinent, China, Myanmar, Thailand, Malaysia, Indonesia, Philippines, New Guinea.

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Phytochemical constituents: Kaempferol,acalyphamide,quinone, sterols, cyanogenic glycoside

Medicinal importance: Constipation, respiratory problems, phlegm Soak few leaves in water for a few hours. Filter and take this water in a dose of 2 teaspoonful.

Intestinal parasite Take fresh leaves of the plant. Wash well and dry completely. Pulverise to prepare powder. Take this powder (¼ to ½ teaspoon) with lukewarm water.

Stomach infections Take clean leaves and grind with few garlic pods. Take this with rice.

Piles Prepare fine powder of Indian-acalypha and Tulsi leaves (Ocimum sanctum) in equal amounts. Take this powder (2-3 pinches) with little amount of ghee thrice a day.

External use Insect bite, Boils, inflammation Take fresh leaves of Indian Acalypha and prepare a paste. Apply this paste on the affected areas.

Skin diseases, eczema, psoriasis, ringworm, tinea versicolor, skin fungal infection Grind handful leaves of Indian-acalypha. Add salt (1 teaspoon) in this paste. Externally apply on skin disorders.

Headaches Apply leaves juice on the affected areas.

Muscular pain Prepare Indian-acalypha medicated oil. For this purpose, extract leaves juice of this medicinal herb. Add this juice in equal amount of sesame oil. Cook this oil, till all water evaporates and only oil remains. Apply thus prepared medicated oil in lukewarm condition.

Bed sores Dry leaves of Indian acalypha in sun and prepare a powder. Apply this powder on the affected areas to get relief from bed sores.

Skin rashes Prepare a poultice of its leaves and apply at affected areas.

Venereal sore (blisters in the genital area) Prepare fine paste of its leaves and apply on the affected areas. Skin wound, itching Mix its leaves paste with haldi (turmeric) and apply at affected area.

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UNIT – IV BASICS IN PHYSIOLOGY ABSORPTION OF WATER ➢ In higher plants water is absorbed through root hairs which are in contact with soil water and form a root hair zone a little behind the root tips. ➢ Root hairs are tubular hair like prolongations of the cells of the epidermal layer of the roots. ➢ The walls of root hairs are permeable and consist of pectic substances and cellulose which are strongly hydrophilic (water loving) in nature. ➢ Root hairs contain vacuoles filled with cell sap.

When roots elongate, the older hairs die, and new root hairs are developed so that they are in contact with fresh supplies of water in the soil.

Mechanism of water absorption is of two types: Active Absorption of Water: In this process the root cells play active role in the absorption of water and metabolic energy released through respiration is consumed.

Active absorption may be of two kinds: (a) Osmotic absorption i.e., when water is absorbed from the soil into the xylem of the roots according to the osmotic gradient.

(b) Non-osmotic absorption i.e., when water is absorbed against the osmotic gradient.

Passive Absorption of Water: It is mainly due to transpiration; the root cells do not play active role and remain passive.

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Active Osmotic Absorption of Water:

➢ First step in the osmotic absorption of water is the imbibition of soil water by the hydro- philic cell walls of root hairs. ➢ Osmotic Pressure (O.P.) of the cell-sap of root hairs is usually higher than the O.P. of the soil water. ➢ Therefore, the Diffusion Pressure Deficit (D.P.D.) and the suction pressure in the root hairs become higher and water from the cell walls enters into them through plasma- membrane (semi-permeable) by osmotic diffusion. ➢ As a result, the O.P., suction pressure and D.P.D. of root hairs now become lower, while their turgor pressure is increased. ➢ Now, the cortical cells adjacent to root hairs have higher O.P., suction pressure and D.P.D. in comparison to the root hairs. ➢ Therefore, water is drawn into the adjacent cortical cells from the root-hairs by osmotic diffusion. ➢ In the same way, the water by cell to cell osmotic diffusion gradually reaches the inner- most cortical cells and the endodermis.

➢ Osmotic diffusion of water into endodermis takes place through special thin walled pas- sage cells because the other endodermal cells have casparian strips on their walls which are impervious to water (Fig. 4.2). ➢ Water from endodermal cells is drawn into the cells of pericycle by osmotic diffusion which now becomes turgid and their suction pressure is decreased. ➢ In the last step, water is drawn into xylem from turgid pericycle cells. (In roots the vascular bundles are radial and protoxylem elements are in contact with pericycle). ➢ It is because in absence of turgor pressure of the xylem vessels (which are non-elastic), the suction pressure of xylem vessels become higher than the suction pressure of the cells of the pericycle. ➢ When water enters into xylem from pericycle, a pressure is developed in the xylem of roots which can raise the water to a certain height in the xylem. This pressure is called as root pressure.

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Active Non-Osmotic Absorption of Water: ➢ Sometimes, it has been observed that absorption of water takes place even when the O.P. of the soil water is higher than the O.P. of cell-sap. ➢ This type of absorption which is non- osmotic and against the osmotic gradient requires the expenditure of metabolic energy probably through respiration.

Passive Absorption of Water: ➢ Passive absorption of water takes place when rate of transpiration is usually high. ➢ Rapid evaporation of water from the leaves during transpiration creates a tension in water in the xylem of the leaves. This tension is transmitted to water in xylem of roots through the xylem of stem and the water rises upward to reach the transpiring surfaces. ➢ As a result, soil water enters into the cortical cells through root hairs to reach the xylem of roots to maintain the supply of water. The force for this entry of water is created in leaves due to rapid transpiration and hence, the root cells remain passive during this process.

External Factors Affecting Absorption of Water: ➢ Available Soil Water ➢ Concentration of the Soil Solution ➢ Soil Air ➢ Soil Temperature

TRANSPIRATION Transpiration is the biological process by which water is lost in the form of water vapour from the aerial parts of the plants.

Parts of plants like stems, small pores on leaves, flowers evaporates the water to the atmosphere. Basically, Transpiration is the process in which water is evaporated in the atmosphere from plant leaves and other parts.

Some amount of water is consumed by roots and rest is evaporated in the atmosphere. Let us study more about types of Transpiration and Stomata of leaves.

Types of Transpiration Transpiration can be of different types depending upon the specialized organ from where it is occurring.

Stomatal transpiration: It is the loss of water through specialized pores in the leaves. It accounts for around 80 to 90% of the total water loss from the plants.

Cuticular transpiration: Cuticle is an impermeable covering present on the leaves and stem. It causes only around 20% transpiration in plants.It is further reduced due to a thicker cuticle in xerophytes. Lenticular Transpiration: Lenticels are the tiny openings present on the woody bark through which transpiration occurs.

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Mechanism of water loss: Leaves also absorb visible and invisible radiations of the Sun and gets heated up. The water vaporizers and is given out in the atmosphere. This results in cooling down of the temperature of the leaves. Transpiration is basically regulated by the opening and closing of stomata.

Structure of Stomach Stomach are the tiny pores present in the epidermal surface of leaves. The pores are guarded by two kidney-shaped cells known as guard cells. The inner wall of guard cell towards the stomata is thicker as compared to the outer walls. Also, the peculiar arrangement of the microfibrils of the guard cells also aids in opening and closing of the stomatal aperture.

The microfibrils are oriented radially rather than longitudinal. This help stomata to open easily. In a dorsiventral dicotyledonous leaf, the number of stomata is a greater on the lower surface as compared to the upper surface. This adaptation helps in reducing the loss of water. In isobilateral leaf in a monocotyledonous plant, the number of stomata is equal on both the surfaces.

Factors affecting Transpiration ➢ Climatic factors like temperature, humidity, wind speed etc. ➢ Plant factors like number and distribution of stomata. ➢ Percent of open stomata. ➢ Water status of the plant.

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➢ The structure of canopy of the tree.

Mechanism of Stomatal Movement The factors which affect stomatal movement are- ➢ Amount of light ➢ The concentration of carbon dioxide ➢ Water supply

The opening and closing of stomata operate as a result of Turgidity changes in the guard cells. During daytime, guard cells photosynthesis due to which osmotic pressure increases.

The guard cells absorb water from the neighbouring cells. Guard cells become turgid. As a result, the outer thin walls of guard cells are pushed out and the inner thicker walls are pulled inwards resulting in stomata to open.

During night or in a condition of water scarcity, guard cells are in a flaccid state and remain closed. Transpiration is the main driving force for the ascent of sap (rising of water in the tall trees through xylem vessels) which depends upon the following physical properties of water.

➢ Cohesion-It is the attraction between water molecules. ➢ Adhesion– The water molecules get attached to the surface of the tracheary elements of xylem. ➢ Surface tension– the ability of water surface to behave like a stretched membrane

These properties give water high tensile strength and high capillarity. Because of this, the water is able to rise in vessels and tracheids of xylem of tall trees. As the water is lost from the leaves during transpiration, a pulling action is generated due to which the water rises high in the tall trees. The force generated by transpiration can create pressure sufficient to lift what over 130 M high.

Significance of Transpiration in Plants The significance of transpiration is explained below:

1. Transpiration helps in the conduction of water and minerals to different parts of the plants. 2. Due to the continuous elimination of water from the plant body, there is a balance of water maintained within the plant. 3. It maintains osmosis and keeps the cells rigid.

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4. A suction force is created by transpiration that helps in the upward movement of water in the plants. 5. Certain hydrophilic salts are accumulated on the surface of the leaves which keeps the leaves moist. 6. It maintains the turgidity of the cells and helps in cell division. 7. Optimum transpiration helps in the proper growth of the plants. 8. The cooling effect of a tree is due to the evaporation of water from its leaves.

PHOTOSYNTHESIS Photosynthesis (Photon = Light, Synthesis = Putting together) is an anabolic, endergonic process by which green plant synthesize carbohydrates (initially glucose) requiring carbon dioxide, water, pigments and sunlight.

➢ The light energy is converted into chemical energy and is stored in the organic matterswhich is usually the carbohydrate and along with O2 form the end products of photosynthesis. ➢ One molecule of glucose (C6H12O6) for instance, contains about 686 k. cal. (2868 kJ) of energy.

Photosynthetic Apparatus – Chloroplast ➢ The chloroplasts in green plants constitute the photosynthetic apparatus. ➢ The chloroplasts of higher plants are discoid or ellipsiodal in shape, 4-6µ in length and 1- 2µ thick. ➢ The chloroplast is bounded by two membranes each app. 50 Å thick and consisting of lipid bilayer and proteins. ➢ The thickness of the two membranes including the space enclosed by them is app. 300 Å. ➢ Chloroplast is filled with a hydrophilic matrix called as stroma in which are embedded grana. ➢ In cross section these lamellae are paired to form sac like structures and have been called as thylakoids. Each grana lamella or thylakoid encloses a space, the loculus or lumen. ➢ Thylakoid membranes and stroma lamellae both are composed of lipid bilayer and proteins.

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Mechanism of Photosynthesis: Photosynthesis is an oxidation reduction process in which water is oxidized and carbon dioxide is reduced to carbohydrate. 1. Light reaction 2. Dark reaction or Biochemical phase.

Light reaction The light reaction takes place in the grana of the chloroplast. Here, light energy gets converted to chemical energy as ATP and NADPH. In this very light reaction, the addition of phosphate in the presence of light or the synthesizing of ATP by cells is known as photophosphorylation.

Photophosphorylation Photophosphorylation is the process of utilizing light energy from photosynthesis to convert ADP to ATP. It is the process of synthesizing energy-rich ATP molecules by transferring the phosphate group into ADP molecule in the presence of light.

Photophosphorylation is of two types: ➢ Cyclic Photophosphorylation ➢ Non-cyclic Photophosphorylation

Cyclic Photophosphorylation

➢ The photophosphorylation process which results in the movement of the electrons in a cyclic manner for synthesizing ATP molecules is called cyclic photophosphorylation. ➢ In this process, plant cells just accomplish the ADP to ATP for immediate energy for the cells. This process usually takes place in the thylakoid membrane and uses Photosystem I and the chlorophyll P700. ➢ During cyclic photophosphorylation, the electrons are transferred back to P700 instead of moving into the NADP from the electron acceptor. This downward movement of electrons from an acceptor to P700 results in the formation of ATP molecules.

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Non-Cyclic Photophosphorylation

➢ The photophosphorylation process which results in the movement of the electrons in a non-cyclic manner for synthesizing ATP molecules using the energy from excited electrons provided by photosystem II is called non-cyclic photophosphorylation. ➢ This process is referred to as non- cyclic photophosphorylation because the lost electrons by P680 of Photosystem II are occupied by P700 of Photosystem I and are not reverted back to P680. Here the complete movement of the electrons is in a unidirectional or in a non- cyclic manner. ➢ During non-cyclic photophosphorylation, the electrons released by P700 are carried by primary acceptor and are finally passed on to NADP. Here, the electrons combine with the protons – H+ which is produced by splitting up of the water molecule and reduces NADP to NADPH2.

Dark Reaction ➢ Dark reaction is also called carbon-fixing reaction. It is a light-independent process in which sugar molecules are formed from the carbon dioxide and water molecules. ➢ The dark reaction occurs in the stroma of the chloroplast where they utilize the products of the light reaction. ➢ Plants capture the carbon dioxide from the atmosphere through stomata and proceed to the Calvin cycle. ➢ In the Calvin cycle, the ATP and NADPH formed during light reaction drives the reaction and convert 6 molecules of carbon dioxide into one sugar molecule i.e. glucose.

It consists of two cycles: 1. C3 Cycle or Calvin cycle 2. C4Cycle or (Hatch and Slack Pathway)

CALVIN CYCLE Calvin cycle or C3 cycle is defined as a set of chemical reactions performed by the plants to reduce carbon dioxide and other compounds into glucose.

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1. Carbon fixation 2. Reduction 3. Regeneration

➢ One molecule of carbon is fixed in each turn of calvin cycle. ➢ One molecule of glyceraldehyde-3 phosphate is created in three turns of calvin cycle. ➢ Two molecules of glyceraldehyde-3 phosphate combine together to form one glucose molecule. ➢ 3 ATP and 2 NADPH molecules are used during the reduction of 3-phosphoglyceric acid to glyceraldehyde-3 phosphate and in the regeneration of RuBP. ➢ 18 ATP and 12 NADPH are consumed in the production of 1 glucose molecule.

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C4 PATHWAY (HATCH AND SLACK PATHWAY)

➢ Every photosynthetic plant follows Calvin cycle but, in some plants,, there is a primary stage to the Calvin Cycle known as C4 pathway. Plants in tropical desert regions commonly follow the C4 pathway. Here, a 4-carbon compound called oxaloacetic acid (OAA) is the first product by carbon fixation. Such plants are special and have certain adaptations as well. ➢ The C4 pathway initiates with a molecule called phosphoenolpyruvate (PEP) which is a 3-carbon molecule. This is the primary CO2 acceptor and the carboxylation takes place with the help of an enzyme called PEP carboxylase. They yield a 4-C molecule called oxaloacetic acid (OAA). ➢ Eventually, it is converted into another 4-carbon compound known as malic acid. Later, they are transferred from mesophyll cells to bundle sheath cells. Here, OAA is broken down to yield carbon dioxide and a 3-C molecule. ➢ The CO2 thus formed is utilized in the Calvin cycle whereas 3-C molecule is transferred back to mesophyll cells for regeneration of PEP. ➢ Corn, sugarcane and some shrubs are examples of plants that follow the C4 pathway. Calvin pathway is a common pathway in both C3 plants and C4 plants, but it takes place only in the mesophyll cells of the C3 Plants but not in the C4 Plants.

Significance of Photosynthesis: ➢ Photosynthesis is a source of all our food and fuel. It is the only biological process that acts as the driving vital force for the whole animal kingdom and for the non- photosynthetic organism. ➢ It drives all other processes of biological and abiological world. It is responsible for the growth and sustenance of our biosphere.

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➢ It provides organic substances, which are used in the production of fats, proteins, nucleoproteins, pigments, enzymes, vitamins, cellulose, organic acids, etc. Some of them become structural parts of the organisms.

➢ It makes use of simple raw materials such as CO2, H2O and inexhaustible light energy for the synthesis of energetic organic compounds.

➢ It is significant because it provides energy in terms of fossil fuels like coal and petrol obtained from plants, which lived millions and millions of years ago.

➢ Plants, from great trees to microscopic algae, are engaged in converting light energy into chemical energy, while man with all his knowledge in chemistry and physics cannot imitate them.

RESPIRATION ➢ Respiration is a biochemical process in which the plants involve using the sugars produced during photosynthesis plus oxygen to produce energy for plant growth.

➢ They use the carbon dioxide (CO2) from the environment to produce sugars and oxygen (O2), which can later be utilized as a source of energy.

C6H12O6 + 6O2 → 6CO2 + 6H2O + 32 ATP (energy)

Structure of Mitochondria(Site of respiration)

Mitochondria are membrane-bound organelles present in the cytoplasm of all eukaryotic cells. Popularly known as the “Powerhouse of the cell”.

➢ The mitochondrion is a double-membraned, rod-shaped structure found in both plant and animal cell. ➢ Its size ranges from 0.5 to 1.0 micrometre in diameter. ➢ The structure comprises an outer membrane, an inner membrane, and a gel-like material called the matrix. ➢ The outer membrane and the inner membrane are made of proteins and phospholipid layers separated by the inter membrane space. ➢ The outer membrane covers has a large number of special proteins known as porins.

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Cristae The inner membrane of mitochondria is rather complex in structure. It has many folds that form a layered structure called cristae, and this helps in increasing the surface area inside the organelle.

Matrix The mitochondrial matrix is a viscous fluid that contains a mixture of enzymes and proteins. It also comprises ribosomes, inorganic ions, mitochondrial DNA, nucleotide cofactors, and organic molecules. The enzymes present in the matrix play an important role in the synthesis of ATP molecules.

Types: Aerobic respiration The respiration that takes place in the presence of oxygen is called aerobic respiration

Anaerobic Respiration The respiration that takes place in the absence of oxygen is anaerobic respiration.

There are two major phases of respiration: i. Glycolysis or EMP pathway ii. Krebs cycle or TCA Cycle

GLYCOLYSIS “Glycolysis is the metabolic process that breaks down of one molecule of glucose into 2 molecules of pyruvic acid.”The process takes place in the cytosol of the cell cytoplasm, in the presence or absence of oxygen. It is otherwise called asEMP pathway (Embden–Meyerhof– Parnas).

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Stage 1 ➢ A phosphate group is added to glucose in the cell cytoplasm, by the action of enzyme hexokinase. ➢ In this, a phosphate group is transferred from ATP to glucose forming glucose,6- phosphate.

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Stage 2 Glucose-6-phosphate is isomerized into fructose,6-phosphate by the enzyme phosphor glucomutase.

Stage 3 The other ATP molecule transfers a phosphate group to fructose 6-phosphate and converts it into fructose 1,6-bisphosphate by the action of enzyme phosphofructokinase.

Stage 4 The enzyme aldolase breaks down fructose 1,6-bisphosphate into glyceraldehyde 3- phosphate and dihydroxyacetone phosphate, which are isomers of each other.

Step 5 Triose-phosphate isomerase converts dihydroxyacetone phosphate into glyceraldehyde 3- phosphate which is the substrate in the successive step of glycolysis.

Step 6 This step undergoes two reactions: The enzyme glyceraldehyde 3-phosphate dehydrogenase transfers 1 hydrogen molecule from glyceraldehyde phosphate to nicotinamide adenine dinucleotide to form NADH + H+.

Glyceraldehyde 3-phosphate dehydrogenase adds a phosphate to the oxidized glyceraldehyde phosphate to form 1,3-bisphosphoglycerate.

Step 7 Phosphate is transferred from 1,3-bisphosphoglycerate to ADP to form ATP with the help of phosphoglycerokinase. Thus two molecules of phosphoglycerate and ATP are obtained at the end of this reaction.

Step 8 The phosphate of both the phosphoglycerate molecules is relocated from the third to the second carbon to yield two molecules of 2-phosphoglycerate by the enzyme phosphoglyceromutase.

Step 9 The enzyme enolase removes a water molecule from 2-phosphoglycerate to form phosphoenolpyruvate.

Step 10 A phosphate from phosphoenolpyruvate is transferred to ADP to form pyruvate and ATP by the action of pyruvate kinase. Two molecules of pyruvate and ATP are obtained as the end products.

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Significance: ➢ It is the process in which a glucose molecule is broken down into two molecules of pyruvate. ➢ The process takes place in the cytoplasm of plant and animal cell. ➢ Six enzymes are involved in the process. ➢ The end products of the reaction include 2 pyruvate, 2 ATP and 2 NADH molecules.

KREB’S CYCLE OR TCA CYCLE ➢ The Krebs cycle, also called the citric acid cycle. ➢ It is the second major step in oxidative phosphorylation. ➢ After glycolysis breaks glucose into Pyruvic acid or Pyruvate, the Krebs cycle transfers the energy from these molecules to electron carriers, which will be used in the electron transport chain to produce ATP.

Reaction 1: Formation of Citrate The first reaction of the cycle is the condensation of acetyl-CoA with oxaloacetate to form citrate, catalyzed by citrate synthase.

Reaction 2: Formation of Isocitrate The citrate is rearranged to form an isomeric form, isocitrate by an enzyme acontinase.

Reaction 3: Oxidation of Isocitrate to α-Ketoglutarate

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In this step, isocitrate dehydrogenase catalyzes oxidative decarboxylation of isocitrate to form α-ketoglutarate.

Reaction 4: Oxidation of α-Ketoglutarate to Succinyl-CoA Alpha-ketoglutarate is oxidized, carbon dioxide is removed, and coenzyme A is added to form the 4-carbon compound succinyl-CoA.

Reaction 5: Conversion of Succinyl-CoA to Succinate CoA is removed from succinyl-CoA to produce succinate.

Reaction 6: Oxidation of Succinate to Fumarate Succinate is oxidized to fumarate.

Reaction 7: Hydration of Fumarate to Malate The reversible hydration of fumarate to L-malate is catalyzed by fumarase (fumarate hydratase).

Reaction 8: Oxidation of Malate to Oxaloacetate Malate is oxidized to produce oxaloacetate, the starting compound of the citric acid cycle by malate dehydrogenase. During this oxidation, NAD+ is reduced to NADH + H+.

ATP Generation Total ATP = 12 ATP ➢ 3 NAD+ = 9 ATP ➢ 1 FAD = 2 ATP ➢ 1 ATP = 1 ATP

Significance of Krebs Cycle 1. Intermediate compounds formed during Krebs cycle are used for the synthesis of biomolecules like amino acids, nucleotides, chlorophyll, cytochromes and fats etc. 2. Intermediate like succinyl CoA takes part in the formation of chlorophyll. 3. Amino Acids are formed from α- Ketoglutaric acid, pyruvic acids and oxaloacetic acid. 4. Krebs cycle (citric Acid cycle) releases plenty of energy (ATP) required for various metabolic activities of cell. 5. By this cycle, carbon skeleton are got, which are used in process of growth and for maintaining the cells.

Respiratory Quotient: Respiratory quotient (RQ) or respiratory ratio is defined as the ratio of the volume of CO2 released to the volume of O2 consumed in respiration per unit time.

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ETS (Electron Transport System) in Respiration of Plants:

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PROTEIN SYNTHESIS Protein synthesis which takes place in the cells of all living things: the production of proteins. This process is called protein synthesis, and it actually consists of two processes — transcription and translation.

In eukaryotic cells, transcription takes place in the nucleus. During transcription, DNA is used as a template to make a molecule of messenger RNA (mRNA). The molecule of mRNA then leaves the nucleus and goes to a ribosome in the cytoplasm, where translation occurs. During translation, the genetic code in mRNA is read and used to make a protein.

These two processes are summed up by the central dogma of molecular biology: DNA → RNA → Protein.

Transcription: Transcription is the first part of the central dogma of molecular biology: DNA → RNA. It is the transfer of genetic instructions in DNA to mRNA. During transcription, a strand of mRNA is made to complement a strand of DNA. You can see how this happens in the diagram below.

Overview of Transcription: Transcription uses the sequence of bases in a strand of DNA to make a complementary strand of mRNA. Triplets are groups of three successive nucleotide bases in DNA. Codons are complementary groups of bases in mRNA.

Steps of Transcription Transcription takes place in three steps: 1. Initiation 2. Elongation 3. Termination.

The steps are illustrated in the figure below: Initiation is the beginning of transcription. It occurs when the enzyme RNA polymerase binds to a region of a gene called the promoter. This signals the DNA to unwind so the enzyme can “read” the bases in one of the DNA strands. The enzyme is ready to make a strand of mRNA with a complementary sequence of bases. 1. Elongation is the addition of nucleotides to the mRNA strand.

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2. Termination is the ending of transcription. The mRNA strand is complete, and it detaches from DNA.

Steps of Transcription: Transcription occurs in three steps: 1. Initiation 2. Elongation 3. Termination.

Processing mRNA In eukaryotes, the new mRNA is not yet ready for translation. At this stage, it is called pre-mRNA, and it must go through more processing before it leaves the nucleus as mature mRNA. The processing may include splicing, editing, and polyadenylation. These processes modify the mRNA in various ways. Such modifications allow a single gene to be used to make more than one protein.

➢ Splicing removes introns from mRNA, as shown in the diagram below. Introns are regions that do not code for the protein. The remaining mRNA consists only of regions called exons that do code for the protein. The ribonucleoproteins in the diagram are small proteins in the nucleus that contain RNA and are needed for the splicing process. ➢ Editing changes some of the nucleotides in mRNA. For example, a human protein called APOB, which helps transport lipids in the blood, has two different forms because of editing. One form is smaller than the other because editing adds an earlier stop signal in mRNA. ➢ Polyadenylation adds a “tail” to the mRNA. The tail consists of a string of As (adenine bases). It signals the end of mRNA. It is also involved in exporting mRNA from the nucleus, and it protects mRNA from enzymes that might break it down.

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Splicing removes introns from mRNA.

Translation ➢ Translation is the second part of the central dogma of molecular biology: RNA → Protein. ➢ It is the process in which the genetic code in mRNA is read to make a protein. ➢ Translation is illustrated in the diagram below. ➢ After mRNA leaves the nucleus, it moves to a ribosome, which consists of rRNA and proteins. The ribosome reads the sequence of codons in mRNA, and molecules of tRNA bring amino acids to the ribosome in the correct sequence. ➢ To understand the role of tRNA, you need to know more about its structure. Each tRNA molecule has an anticodon for the amino acid it carries. An anticodon is complementary to the codon for an amino acid. ➢ For example, the amino acid lysine has the codon AAG, so the anticodon is UUC. Therefore, lysine would be carried by a tRNA molecule with the anticodon UUC. Wherever the codon AAG appears in mRNA, a UUC anticodon of tRNA temporarily binds. While bound to mRNA, tRNA gives up its amino acid. ➢ With the help of rRNA, bonds form between the amino acids as they are brought one by one to the ribosome, creating a polypeptide chain. The chain of amino acids keeps growing until a stop codon is reached.

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Summary ➢ Protein synthesis is the process in which cells make proteins. It occurs in two stages: transcription and translation. ➢ Transcription is the transfer of genetic instructions in DNA to mRNA in the nucleus. It includes three steps: initiation, elongation, and termination. After the mRNA is processed, it carries the ➢ instructions to a ribosome in the cytoplasm. ➢ Translation occurs at the ribosome, which consists of rRNA and proteins. In translation, the instructions in mRNA are read, and tRNA brings the correct sequence of amino acids to the ribosome. Then, rRNA helps bonds form between the amino acids, producing a polypeptide chain. ➢ After a polypeptide chain is synthesized, it may undergo additional processing to form the finished protein.

TYPES OF RNA Ribosomal RNA (rRNA) In the synthesis of protein, three types of RNA function. The first type is called ribosomal RNA (rRNA). This form of RNA is used to manufacture ribosomes. Ribosomes are ultramicroscopic particles of rRNA and protein.

Transfer RNA (tRNA) Transfer RNA exists in the cell cytoplasm and carries amino acids to the ribosomes for protein synthesis. When protein synthesis is taking place, enzymes link tRNA molecules to amino acids in a highly specific manner. For example, tRNA molecule X will link only to amino acid X; tRNA molecule Y will link only to amino acid Y.

Messenger RNA (mRNA) The third form of RNA is messenger RNA (mRNA). In the nucleus, messenger RNA is constructed from DNA’s code of base pairs and carries the code into the cytoplasm or to the rough endoplasmic reticulum where protein synthesis takes place. Messenger RNA is synthesized in the nucleus using the DNA molecules. During the synthesis, the genetic information is transferred from the DNA molecule to the mRNA molecule. In this way, a genetic code can be used to synthesize a protein in a distant location. RNA polymerase, an enzyme, accomplishes mRNA, tRNA, and rRNA synthesis.

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UNIT – V CELL ORGANELLES GENETICS AND GENETIC ENGINEERING

CELL ORGANELLES The cellular components are called the Cell Organelles. These cell organelles are membrane-bound, present within the cells and are distinct in their structures and functions. They coordinate with their functions efficiently for the normal functioning of the cell. Few of them functions providing shape and support, whereas some are involved in the locomotion and reproduction of a cell. There are various organelles present within the cell and are classified into three categories based on the presence or absence of membrane.

Organelles without membrane: The Cell wall, Ribosomes, and Cytoskeleton are membrane-bound cell organelles. They are present both in prokaryotic cell and the eukaryotic cell.

Single membrane-bound organelles: Vacuole, Lysosome, Golgi Apparatus, Endoplasmic Reticulum are single membrane- bound organelles present only in a eukaryotic cell.

Double membrane-bound organelles: Mitochondria and chloroplast are double membrane-bound organelles present only in a eukaryotic cell.

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Function of Cell Organelles Cell Organelles Structure Functions Cell membrane A double membrane composed of Provides shape, protects the inner lipids and proteins. Present both in organelle of the cell and acts as a plant and animal cell. selectively permeable membrane. Centrosomes Composed of Centrioles and found It plays a major role in organizing only in the animal cells. the microtubule and Cell division. Chloroplasts Present only in plant cells and Sites of photosynthesis. contains a green-coloured pigment known as chlorophyll. Cytoplasm A jelly-like substance, which consists Responsible for the cell’s of water, dissolved nutrients and metabolic activities. waste products of the cell. Endoplasmic A network of membranous tubules, Forms the skeletal framework of Reticulum present within the cytoplasm of a cell. the cell, involved in the Detoxification, production of Lipids and proteins. Golgi apparatus Membrane-bound, sac-like organelles, It is mainly involved in secretion present within the cytoplasm of the and intracellular transport. eukaryotic cells. Lysosomes A tiny, circular-shaped, single Helps in the digestion and membrane-bound organelles, filled removes wastes and digests dead with digestive enzymes. and damaged cells. Therefore, it is also called as the “suicidal bags”. Mitochondria An oval-shaped, membrane-bound The main sites of cellular organelle, also called as the “Power respiration and also involved in House of The Cell”. storge energy in the form of ATP molecules. Nucleus A largest, double membrane-bound Controls the activity of the cell, organelles, which contains all the helps in cell division and controls cell’s genetic information. the hereditary characters. Peroxisome A membrane-bound cellular organelle Involved in the metabolism of present in the cytoplasm, which lipids and catabolism of long- contains the reducing enzyme. chain fatty acids. Plastids Double membrane-bound organelles. Helps in the process of There are 3 types of plastids: photosynthesis and 1. Leucoplast –Colourless plastids. pollination, Imparts colour for 2. Chromoplast–Blue, Red, and Yellow leaves, flowers and fruits and colour plastids. stores starch, proteins and fats. 3. Chloroplast – Green coloured plastids. Ribosomes non-membrane organelles, found Involved in the Synthesis of floating freely in the cell’s cytoplasm Proteins. or embedded within the endoplasmic reticulum. Vacuoles A membrane-bound, fluid-filled Provide shape and rigidity to the organelle found within the cytoplasm. plant cell and helps in digestion, excretion, and storage of substances. PLANT TISSUE SYSTEM

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A tissue is a cluster of cells that are alike in configuration and work together to attain a specific function. Different types of plant tissues include permanent and meristematic tissues.

Parenchyma These are alive, polygonal cells with a big central vacuole, and have intercellular spaces amidst them. Parenchymatous cells create ground tissue and pith. 1. Parenchyma comprising of chloroplasts are termed as chlorenchyma. The chlorenchyma helps in photosynthesis. 2. Parenchyma which comprises of big air voids is called aerenchyma. Buoyancy is the main purpose the aerenchyma serves. 3. Some parenchymatous cells perform as storage chambers for starch in vegetable and fruits.

Collenchyma These are stretched out living cells with minute intercellular gaps. Their cell walls are made up of pectin and cellulose. Collenchyma is found in the marginal regions of leaves and stems and offers flexibility with the structural framework and mechanical support in plants.

Sclerenchyma These are elongated, dead cells with lignin deposits in their cell wall. They have no intercellular gaps. Sclerenchyma is found in the covering of seeds and nuts, around the vascular tissues in stems and the veins of leaves. Sclerenchyma provides strength to the plant.

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Xylem It helps in the transport of dissolved substances and water all through the plant. The diverse components of the xylem include vessels, tracheids, xylem fibres and xylem parenchyma. Xylem fibres and Tracheids are made up of lignin, which provides structural support to the plant.

Phloem This tissue helps in the transportation of food all through the plant. The diverse elements of phloem include phloem fibres, sieve tubes, phloem parenchyma and companion cells.

Protective tissues These provide fortification to the plant. They include the cork and epidermis.

Epidermis: Its a layer of cell that makes up making up an outer casing of all the structures in the plant. The stomata perforate the epidermis at certain places. The stomata help in loss of water and gaseous exchange.

Cork: This is the external protective tissue which substitutes the epidermal cells in mature stems and roots. Cork cells are lifeless and lack intercellular gaps. Their cell walls are coagulated by suberin which makes them impervious to gas and Water Molecules.

GENETICS - MENDELISM Mendelian inheritance, also called Mendelism, the principles of heredity formulated by Austrian-born botanist, teacher, and Augustinian prelate Gregor Mendel in 1865. He is a father of genetics.

These principles compose what is known as the system of particulate inheritance by units, or genes.

The later discovery of chromosomes as the carriers of genetic units supported Mendel’s two basic laws, known as the law of segregation and the law of independent assortment.

In modern terms, the first of Mendel’s laws states that genes are transferred as separate and distinct units from one generation to the next. The two members (alleles) of a gene pair, one on each of paired chromosomes, separate during the formation of sex cells by a parent organism.

One-half of the sex cells will have one form of the gene, one-half the other form; the offspring that result from these sex cells will reflect those proportions.

A modern formulation of the second law, the law of independent assortment, is that the alleles of a gene pair located on one pair of chromosomes are inherited independently of the alleles of a gene pair located on another chromosome pair and that the sex cells containing various assortments of these genes fuse at random with the sex cells produced by the other parent.

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Mendel also developed the law of dominance, in which one allele exerts greater influence than the other on the same inherited character. Mendel developed the concept of dominance from his experiments with plants, based on the supposition that each plant carried two trait units, one of which dominated the other. For example, if a pea plant with the alleles T and t (T = tallness, t = shortness) is equal in height to a TT individual, the T allele (and the trait of tallness) is completely dominant. If the Tt individual is shorter than the T T but still taller than the t t individual, T is partially or incompletely dominant—i.e., it has a greater influence than t but does not completely mask the presence of t, which is recessive.

MONOHYBRID CROSS Introduction The mystery of genetics was unlocked during the mid-nineteenth century by Gregor Mendel. He conducted an experiment on pea plants by cultivating the pea plants and observing the pattern of inheritance in different stages of generation.

Mendel investigated the pairs of pea plants with one contrasting trait. Mendel studied on the following seven characters with contrasting traits:

i. Flower colour: Violet/white ii. Flower position: Axial/terminal iii. Pod colour: Green/yellow iv. Pod shape: Inflated/constricted v. Seed colour: Yellow/green vi. Seed shape: Round/wrinkled vii. Stem height: Tall/dwarf

He crossed two homozygous individuals which resulted in heterozygous offsprings. This was known as the monohybrid cross.

Definition: “A monohybrid cross is the hybrid of two individuals with homozygous genotypes which result in the opposite phenotype for a certain genetic trait.”

“The cross between two monohybrid traits (TT and tt) is called a Monohybrid Cross.” Monohybrid cross is responsible for the inheritance of one gene. It can be easily shown through a Punnett Square.

Monohybrid cross is used by geneticists to observe how homozygous offsprings express heterozygous genotypes inherited from their parents.

Example Gregor Mendel’s Peas For monohybrid cross, Mendel began with a pair of pea plants with two contrasting traits i.e.,one tall and another dwarf.

The cross-pollination of tall and dwarf plants resulted in tall plants. All the hybrid plants were tall. He called this as a first hybrid generation (F1) and offspring were called Filial1 or F1 progeny.

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He conducted an experiment with all seven contrasting pairs. He observed that the entire F1 progeny showed one pattern in their behaviour i.e., they resembled one of the parents. Another parent character was completely absent.

He continued his experiment with self-pollination of F1 progeny plants. Surprisingly, he observed that one out of four plants were dwarf while the other three were tall. The tall and the short plants were in the ratio of 3:1.

He also noted that no progeny was in intermediate height i.e., no blending was observed. The result was the same for other traits of plants too, and he called them second hybrid generation and offspring were called Filial2 or F2 progeny.

Mendel observed that traits which were absent in F1 generation had reappeared in the F2 generation. He called such suppressed traits as recessive traits and expressed traits as dominant traits. He also concluded that some ‘factors’ are inherited by offspring from their parent over successive generations.

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Later, these ‘factors’ were called genes. Genes are responsible for the inheritance of traits from one generation to another. Genes consist of a pair of alleles which code for different traits. If a pair of alleles is the same i.e., TT or tt, such alleles are called homozygous pair while those that are different or non-identical (e.g. Tt) are called heterozygous pair.

DIHYBRID CROSS A dihybrid cross is a breeding experiment between two organisms which are identical hybrids for two traits. In other words, a dihybrid cross is a cross between two organisms, with both being heterozygous for two different traits. The individuals in this type of trait are homozygous for a specific trait. These traits are determined by DNA segments called genes.

In a dihybrid cross, the parents carry different pair of alleles for each trait. One parent carries homozygous dominant allele, while the other one carries homozygous recessive allele. The offsprings produced after the crosses in the F1 generation are all heterozygous for specific traits.

Examples Mendel took a pair of contradicting traits together for crossing, for example colour and the shape of seeds at a time. He picked the wrinkled-green seed and round-yellow seed and crossed them. He obtained only round-yellow seeds in the F1 generation. This indicated that round shape and yellow colour of seeds are dominant in nature.

Meanwhile, the wrinkled shape and green colour of seeds are recessive traits. Then, F1 progeny was self-pollinated. This resulted in four different combinations of seeds in the F2 generation. They were wrinkled-yellow, round-yellow, wrinkled-green seeds and round-green in the phenotypic ratio of 9:3:3:1.

During monohybrid cross of these traits, he observed the same pattern of dominance and inheritance. The phenotypic ratio 3:1 of yellow and green colour and of round and wrinkled seed shape during monohybrid cross was retained in dihybrid cross as well.

Consider “Y” for yellow seed colour and “y” for green seed colour, “R” for round shaped seeds and “r” for wrinkled seed shape. Thus, the parental genotype will be “YYRR” (yellow- round seeds) and “yyrr” (green-wrinkled seeds).

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GENETIC ENGINEERING

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Genetic engineering primarily involves the manipulation of genetic material (DNA) to achieve the desired goal in a pre-determined way. It is also called as Gene manipulation or Recombinant DNA (rDNA) technology or Gene cloning (molecular cloning) or Genetic modifications v. New genetics.

Enzymes used in gene cloning a. Restriction Endonucleases b. Exonucleases c. DNA ligases d. DNA polymerase

Restriction Endonuclease: These enzymes serve as important tools to cut DNA molecules at specific sites, which is the basic need for rDNA technology. These are the enzymes that produce internal cuts (cleavage) in the strands of DNA, only within or near some specific sites called recognition sites/recognition sequences/ restriction

Page 59 of 67 STUDY MATERIAL FOR B.SC MB BOTANY FOR COMPETITIVE EXAMINATION SEMESTER -IV, ACADEMIC YEAR 2020 - 21 sites 01 target sites. Such recognition sequences are specific for each restriction enzyme. Restriction endonuclease enzymes are the first necessity for rDNA technology.

The presence of restriction enzymes was first of all reported by W. Arber in the year 1962. He found that when the DNA of a phage was introduced into a host bacterium, it was fragmented into small pieces. This led him to postulate the presence of restriction enzymes. The first true restriction endonuclease was isolated in 1970s from the bacterium E. coli by Meselson and Yuan.

Another important breakthrough was the discovery of restriction enzyme Hind-II in 1970s by Kelly, Smith and Nathans. They isolated it from -the bacterium Haemophilus influenza. In the year 1978, the Nobel Prize for Physiology and Medicine was given to Smith, Arber and Nathans for the discovery of endonucleases.

Types of Restriction Endonucleases: There are 3 main categories of restriction endonuclease enzymes: i. Type-I Restriction Endonucleases ii. Type-II Restriction Endonucleases iii. Type-III Restriction Endonucleases

(i) Type-I Restriction Endonucleases: These are the complex type of endonucleases which cleave only one strand of DNA. These enzymes have the recognition sequences of about 15 bp length.

(ii) Type-II Restriction Endonucleases: These are most important endonucleases for gene cloning and hence for r DNA technology. These enzymes are most stable. They show cleavage only at specific sites and therefore they produce the DNA fragments of a defined length. These enzymes show cleavage in both the strands of DNA, immediately outs. Only Type II Restriction Endonucleases are used for gene cloning due to their suitability. Examples: Hinfl, EcoRI, PvuII, Alul, Haelll etc.

(iii) Type-III Restriction Endonucleases: These are not used for gene cloning. They are the intermediate enzymes between Type-I and Type-II restriction endonuclease. e.g. Hinf III, etc.

Nature of cleavage by Restriction Endonucleases: The nature of cleavage produced by a restriction endonuclease is of considerable importance.

They cut the DNA molecule in two ways: Many restriction endonucleases cleave both strands of DNA simply at the same point within the recognition sequence. As a result of this type of cleavage, the DNA fragments with blunt ends are generated. In the other style of cleavage by the restriction endonucleases, the two strands of DNA are cut at two different points. Such cuts are termed as staggered cuts and this results into the generation of protruding ends i.e., one strand of the double helix extends a few bases beyond the other strand. Such ends are, called cohesive or sticky ends.

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Such ends have the property to pair readily with each other when pairing conditions are provided. Another feature of the restriction endonucleases producing such sticky ends is that two or more of such enzymes with different recognition sequences may generate the same sticky ends.

(b) Exonucleases: Exonuclease is an enzyme that removes nucleotides from the ends of a nucleic acid molecule. An exonuclease removes nucleotide from the 5′ or 3′ end of a DNA molecule. An exonuclease never produces internal cuts in DNA. In rec DNA technology, various types of exonucleases are employed like Exonuclease Bal31, E. coli exonuclease III, Lambda exonuclease, etc.

(c) DNA ligase: The function of these enzymes is to join two fragments of DNA by synthesizing the phosphodiester bond. They function to repair the single stranded nicks in DNA double helix and in rec DNA technology they are employed for sealing the nicks between adjacent nucleotides. This enzyme is also termed as molecular glue.

(d) DNA polymerases: These are the enzymes which synthesize a new complementary DNA strand of an existing DNA or RNA template. A few important types of DNA polymerases are used routinely in genetic engineering. One such enzyme is DNA polymerase which, prepared from E coli. The

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Klenow fragment of DNA polymerase-I .s employed to make the protruding ends double- stranded by extension of the shorter strand.

Another type of DNA polymerase used in genetic engineering is Taq DNA polymerase which is used in PCR (Polymerase Chain Reaction).

Reverse transcriptase is also an important type of DNA polymerase enzyme for genetic engineering. It uses RNA as a template for synthesizing a new DNA strand called as cDNA a e complementary DNA).

PLANT TISSUE CULTURE Tissue culture is the in vitro aseptic culture of cells, tissues, organs or whole plant under controlled nutritional and environmental conditions. It is otherwise called as clonal propagation.

Theory of totipotency provides that it should be possible to produce an organism from any one nucleated cell of the body, since all the information needed to specify an organism is contained in its DNA.

Consequent upon the pioneering research, plant tissue culture has found wide application in agriculture, horticulture, forestry and plant breeding.

Types of Plant tissue culture 1. Seed Culture 2. Embryo Culture 3. Callus Culture 4. Organ Culture 5. Protoplast Culture 6. Meristem Culture

Steps of tissue culture: Selection of mother plant:

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Selection of mother plant with all desirable characters like high yield, good quality and disease resistance plays crucial role in tissue culture.

Collection of ex-plants: A cut portion of plant organ or tissue used for initiation of an in vitro culture is called explants. These can be shoot tips, root tips, leaves, tuber etc. Shoot tips are generally preferred.

Sterilization of ex-plants: The ex-plants should be washed thoroughly with sterilizing agents, such as sodium hypochlorite, mercuric chloride solution and then washed with sterile distilled water before transferring to the nutrient media.

Preparation of culture media: The appropriate composition of the nutrient medium largely determines the success of the cultures. In general, the media contains inorganic salts, vitamins, growth regulators (auxins, cytokinins, gibberellins), variety of carbohydrates, organic supplements such as yeast, malt extracts, coconut water and agar boiled in sufficient quantity of water.

Then it is sterilized in an autoclave and stored in media room. Now ready-made culture media are available with the scientific suppliers and they can be directly used for the purpose

Transfer of ex-plants into flasks containing nutrient media: This is done by experienced person in inoculation room under sterilized conditions. The sterilized ex-plants are transferred with the help of inoculation medium into the conical flask or jars containing culture media. Such flasks are kept in growth room where there will be controlled air, light, humidity and temperature.

When the tissues are placed on the culture medium within a few days a mass of cells called callus will develop due to active division of the tissue cells and within 3-6-week multiple shoots in bunches will appear from the callus.

Method of sub-culture and production of plants: Multiple shoots are separated and transferred to the flask containing media in laminar airflow chamber. The medium is modified in such a way that roots and vegetative parts develop quickly. In one to three weeks young plants may develop from the cultured tissue.

Method of hardening: This is a method in which the tissue culture plants developed in artificial media are habituated to grow in natural environment. Firstly, these plants are taken out from nutrient media and washed thoroughly with water. Then these plants are grown in netted plastic pots filled with liquid nutrient medium and kept in green house for 6 – 8 weeks.

This is called Primary hardening. Afterwards the plants are transferred to polybags filled with potting mixture and grown under shaded house for 6 – 8 weeks. This is called Secondary hardening. After secondary hardening the plants are suitable for growing in farmer’s fields

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Applications of Tissue Culture Technique: i. Tissue culture is used to develop thousands of genetically identical plants from one single parent plant known as soma clones, and this process is known as micropropagation. ii. The method offers an advantage over other methods as it can be used to develop disease free plants from disease-rode plants by using their meristems (apical and axillary) as explants. iii. Since this method produces new plantlets by the score of thousands, it has been used extensively for production of commercially important plants including food plants like tomato, banana, apple etc. iv. The most notable example of the application of micropropagation was observed in the farming of orchids as it rose exponentially due to the availability of millions of plantlets thanks to tissue culture methods.

BIOFERTILIZERS Biofertilizers are substances that contain microorganisms, which when added to the soil increase its fertility and promotes plant growth.

It comprises living organisms which include mycorrhizal fungi, blue-green algae, and bacteria. Mycorrhizal fungi preferentially withdraw minerals from organic matter for the plant whereas cyanobacteria are characterized by the property of nitrogen fixation.

Nitrogen fixation is defined as a process of converting the di-nitrogen molecules into nitrogen compounds. Some bacteria convert insoluble forms of soil phosphorus into soluble forms.

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Types of Biofertilizers a. Bacteria b. Fungi c. Cyanobacteria

Bacteria Nitrogen-fixing bacteria present in the root nodules in legumes. This great example of biofertilizers. The nodules are formed by the association of the bacterium ‘Rhizobium’ with the roots of these plants. This association is beneficial and is, therefore, called ‘symbiotic’.

The nodules help in fixing atmospheric nitrogen into organic forms which can then be used as nutrition by the plants. Adding Rhizobium cultures to fields has become a common practice to ensure an adequate amount of nitrogen in the soil.

Other examples of bacteria they release phosphate from bound and insoluble states. The biofertilizers include Azospirillum and Azotobacter. These bacteria are free-living in the soil. Azotobacter is usually used with crops like cotton, wheat, mustard, maize.

Fungi Symbiotic associations exist between plants and fungi too. These associations are called ‘Mycorrhizae’. The fungus in this association absorbs phosphorus from the soil and provides it to the plant. Eg: VAM fungi, Ectomycorrhiza, Entomycorrhiza.

Plants that grow with these associations also show other advantageous characteristics such as:

i. Tolerance to drought conditions and salinity. ii. Resistance to root-borne pathogens. iii. An overall increase in plant growth and development.

Cyanobacteria i. These are blue-green bacteria found in water and on land. ii. They also help fix atmospheric nitrogen. iii. Examples are Oscillatoria, Nostoc, Anabaena etc. iv. The symbiotic association between the aquatic fern Azolla and Anabaena is very important for rice fields. v. In this association, Anabaena receives carbon and nitrogen from the plant in exchange for fixed nitrogen. vi. This adds organic matter to the soil enhancing the fertility of rice fields.

Bio-fertilizers are important for the following reasons: a. Biofertilizers improve soil texture and yield of plants. b. They do not allow pathogens to flourish. c. They are eco-friendly and cost-effective. d. Biofertilizers protect the environment from pollutants since they are natural fertilizers. e. They destroy many harmful substances present in the soil that can cause plant diseases. f. Biofertilizers are proved to be effective even under semi-arid conditions.

Applications of Biofertilizers

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Seedling root dip This method is applicable to rice crops. The seedlings are planted in the bed of water for 8-10 hours.

Seed Treatment The seeds are dipped in the mixture of nitrogen and phosphorus fertilizers. These seeds are then dried and sown as soon as possible.

Soil Treatment The bio-fertilizers along with the compost fertilizers are mixed and kept for one night. This mixture is then spread on the soil where the seeds have to be sown.

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