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Home , Domain (biology), Peptidoglycan, Prokaryote, Taxis

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Archea and - The As late as 1977, all prokaryotes were put into one single called . Taxonomists no longer accept that concept. Some prokaryotes are more closely related to than other prokaryotes. Most taxonomists now accept the concept of super kingdoms or domains. Two of the three domains are prokaryotes

EUBACTERIA Bacteria I. Three common shapes (cocci, , spirilla) II. Small 0.5-5 mm Within their domains, identification of microbes begins with their physical appearance, followed by biochemical and genetic tests.

SHAPE is/was the most commonly used physical appearance for determination of .

Classified by shape, size, staining, environment, & color Cynobacteria & Autotroph Bacteria Flagellated Bacteria Strep bacteria of Rheumatic Fever

E.Coli dividing Nostococ

III. Bacterial wall made of carbohydrate that are connected by polypeptide chains (). Gram- positive bacteria (stain purple with Gram-stain) have cell walls with just the peptidoglycan wall connected to plasma membrane. Gram-negative bacteria (stain pink) have peptidoglycan wall sandwiched between two membranes. The of Archae are made from and certain but NOT . Gram positive bacteria

Gram negative bacteria

Have a thin layer of peptidoglycan in their cell wall. AND have with channels in the cell Have an extra layer of membrane. This keeps dyes peptidoglycan in their cell (along with ) out! wall, and retain dye. http://www.sirinet.net/~jgjohnso/monerans.html

Some prokaryotes have a second layer outside the cell wall. -Capsule-sticky layer of carbohydrates or proteins. -Fimbriae-protein appendages that allows the to attach to surfaces

Bacilli Spirilla Cocci

Nostoc

Oscolitoria

Gloeocapsa

IV. Nucloid region-area where circular DNA is located. Chromosome lacks (some prokaryotes in Archae do). May also contain smaller circular pieces of DNA or .

V. are smaller than cytoplasmic eukaryotic ribosomes. VI. Some prokaryotes have infoldings of the plasma membrane similar to cristae (mitochondria) and some photosynthetic prokaryotes have internal membranes similar to thylakoid () VII. Some prokaryotic cells have flagella. The is different from eukaryotic cells. It is a solid core of protein (1/10th width). It is driven by a system of rings in the cell wall. ATP pumps transports H+ out cell.` When the H+ diffuse back in it powers the flagella which rotates like a helicopter rotor. Flagellated prokaryotes can exhibit moving toward or away chemicals, nutrients or .

Reproduction- is via binary . Bacteria can obtain genetic variation via conjugation, transformation, or Conjugation-(Lederberg & Tatum) 1. Conjugation-Certain bacteria that have been mutated, would need additonal nutrients in their media in to grow. Bacteria without these mutations will grow on minimal media. E.Coli had been mutated and 2 different strains were found #1- needed methonie and vitamin biotin but could make its own leucine and threonine. #2-needed threonine and leucine but could not make its own methonine and vitamin biotin. When these two types were mixed, there emerged some new cells that had the ability to grow on minimal media. Conclusion: There had to be some exchange of or recombination of genes. Recombination has occurred because the new cells can grow on minimal media. It was also discovered that in addition to the main chromosome, prokaryotic cells contained smaller circles of DNA (plasmids) which also contained genes. The arrow points to a in a lysed E.Coli cell which is then magnified. This plasmid contains genes that makes the cell resistant to the . Plasmids replicate independent of the main chromosome. These plasmids are being replicated.

In order for conjugation to occur there must be 2 different mating types F+ (male) and F- (female). F+ males have a plasmid (sex factor) which is replicated. When a F+ and F- meet, they form a cytoplasmic bridge or . The copied F+ plasmid is transferred to F- making it F+. The population never completely is converted to F+ because 1. F- can undergo bacterial reproduction (fission) faster than F+ can conjugate. 2. The formation of the pilus, allows for cetain to attack, and they only attack F+ cells. Conjugating bacteria with Some F+ plasmids are inserted into the pilli connecting the the main chromosome becoming Hfr cells to one another to (high frequency recombinants). exchange DNA. When Hfr conjugates with F-, the entire main chromosome is replicated. However during transfer only part of the chromosome is transferred. The for Hfr is usually at the end of the chromosome, so that the receiving cell F- will stay an F-. The longer the pilus stays together, the more genes transferred. Autonomous plasmids-Plasmids that never integrate themselves into the chromosome. They may carry genes that include antibiotic resistance or a virulence factor. Plasmids have the ability to replicate themselves so that a prokaryotic cell may have 1,000 to 3,000 copies of it. 2. Transformation- Involves prokaryotic cells taking up extraneous DNA from the environment. uses this technique in transforming bacteria and using engineered plasmids. 3.Transduction- Bacterial cells obtaining DNA via a viral vector. The rapid reproduction, mutations, and allows for a great variety in their metabolic pathways.

-Photoautotroph-does and uses CO2 as its carbon source

-Chemoautotroph-uses CO2 to make organic compounds on its own and uses chemicals like H2S and NH3 for instead of

-Photoheterotroph-uses light for energy but obtains carbon from an organic source.

-Chemoheterotroph-uses organic compounds for both an energy source and carbon source. Most are decomposers or that break organic compounds down. Types of cell respiration -Obligate aeorbes must use oxygen for cell respiration or will die without it

-- oxygen is not used for cell respiration and the cell is actually poisoned by it.

-Faculative anaerobes-can use oxygen when present or do fermentation if oxygen is not present.

Nitrogen fixation Some prokaryotes have the ability to “fix” atmospheric nitrogen (N2) into ammonia NH3. Then the ammonia can be converted into nitrates and nitrites. The nitrogen compounds then can be converted into amino . Important part of nitrogen cycle. Some prokaryotes live in symbiotic relationships with this pathway. The root nodules of legumes contain nitrogen fixing bacteria. Types of photosynthesis-Some prokaryotes are photosynthetic. There are two types of photosynthesis in prokaryotes

Type I that gives off O2 as a by product. Contains photosystem I and II like higher Contains chlorophyll a like higher plants Splits water

6 CO2 + 6 H2O -> C6H12O6 + 6 O2 Type II that does not give off O2 as a by product. Contains only photosystem I Contains bacteriochloropyll Splits

CO2 + 2H2S -> (CH2O)n + 2 S Bacteria-Supergroups 1. -Gram negative with 5 subgroups. Metabolic diverse photoautotrophs, chemoautotrophs, and . Some are aerobic while others are anaerobes. 2. Chlamydias-Obligate pararsites only live in other cells. Major cause blindness. 3. Spirochetes-Spiraled shaped with internal like flagellum. Caused syphilis and . 4. -does type I photosynthesis generating oxygen. Some cells specialized () for fixing nitrogen 5. Gram-positive bacteria-Metabolic diverse group. Some obligate parasites, some secrete antibiotics.

Domain -Supergroups can live in extreme environments and more normal environments. More closely related to eukaryotes than other prokaryote 1. Extreme can tolerates saline enviroments. Tolerance from slightly saline to over 9% saline (Marine enviroments is 3.5% saline). 2. Exterme can tolerate very hot environments. Proteins are very stable at this and DNA remains as a double helix. One strain of Geogemma barossii can tolerate temperature of over 121o C.

3. - use CO2 to oxidize H2 to make methane gas. Obligate anaerobes. Found under ice, swamps, guts of cattle, and . 4. Moderate environment-many prokaryotes from the Domain Archaea are live in moderate environments. ALL ABOUT ARCHAEBACTERIA

• Archaea are highly diverse , both morphologically (form and structure) and physiologically (function).

• The organisms' possible shapes include spherical, rod- shaped, spiral, lobed, plate-shaped, irregularly shaped, and pleomorphic(2 or more shapes during lifetime). There are many different types of Archaea that live in extremely diverse environments.

• Modern-day Archaebacteria are found in extreme environments, such as areas of intense heat or high salt concentration.

Prokaryotes in the environment Symbiotic relationships- Mutualistic- Ex-certain bacteria in your gut are important to the digestive system and the bacteria benefit by the food that is provided to them. Commensalistic-Ex There a many bacteria living on the surface of the skin. They do not harm or provide any benefit to the epidermal cells. The epidermal cells provide oils, food and a to live Parasitic-Ex-Some prokaryotes are pathogens (cause disease). Many bacterial diseases can be treated with antibiotics which are compounds that destroy prokaryotic cells but not eukaryotic cells. Usually the disease is caused by either an (made and secreted by the prokaryote) or endotoxin (made by the prokaryote and only released if the prokaryote dies). Botulism is caused by an exotoxin made by botulinum and typhoid fever is caused by an endotoxin made by Salmonella typhi.

Prokaryotes are the most dominant organisms on this . Without them, as we know would not exist. They are important in -decomposers -nutrient recycling - -food industry - -medicine -producers in food chains. V. The 4 main functions of bacteria

1. Nitrogen fixation 2. Recycling of nutrients 3. Food & medicines 4. Bacteria cause diseases Nitrogen wastes are excreted & cycled by bacteria Nitrogen in & protein

Bacteria convert Ammonia nitrogen Ammonia to usable Is excreted in urine Nitrate fertilizer Making cheese & yogurt with bacteria This chart compares and contrast three different domains. It is based on the sequencing of the rRNA found in the small subunit. The Archae prokaryotes are more closely related to eukaryotes than it is to the Bacteria prokaryotes.