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Bacteria and Fungi Nutrition – bacteria and fungi Reproduction – bacteria Reproduction – fungi Extracellular digestion Occurs by binary fission – asexual (mitosis) as Spores: small, tough coated reproductive cells. 1. secrete enzymes 2. digest the food 3. reabsorb the often as every 20 minutes under favourable* Sporangium: swellings at the tips of hyphae that produce/ digested food conditions. The DNA copies itself, the cell contain/release spores for reproduction which are dispersed in Fungi are saprophytes feeding on dead organic material. They membrane pinches the cytoplasm in half, and the air and grow into new fungi (role of spread). feed by extracellular digestion. This means they secrete two bacteria form (identical). sporangium spores enzymes through the walls of their fine feeding hyphae, which *enough food, oxygen (if aerobic), moisture, warmth, space. break down the food into nutrients. The digested nutrients are 1. lag phase 2. log or exponential growth (population doubling Sporangia (plural of sporangium) above then reabsorbed through the hyphae wall. The nutrients are in each reproductive period) 3. stationary and 3 ground burst to release the light spores 4 used for growth or used in respiration to release energy. 4. death phase No. into air so they are easily spread. Exponential growth doesn’t keep occurring as 2 Sporangia disperse spores so new fungi Bacteria and fungi thrive in warm, moist conditions, rich in bacteria run out of nutrients and space and can grow further away. nutrients. 1 become poisoned by their excretory products. time Yeast reproduces by budding. Growth – bacteria and fungi Reproduction – viruses AS90168 Virus attaches to cell (via protein coat), penetrates cell Grow bigger by using nutrients gained by digestion of food, membrane and injects viral genetic material. Viral genetic and energy released from the digested food by Describe biological ideas relating to material is replicated using host cellular machinery. New RESPIRATION. how humans use and are affected by protein coats are made and assembled with the new genetic Once cells reach a certain size they become too big to be micro-organisms info. into new viruses. Cell bursts releasing the new viruses efficient and will divide to make more cells. Level 1 2 credits the cell usually dies in the process. If host cell is a bacterium Viruses don’t grow - they have no chemical processes of their the virus is called a bacteriophage. How humans use and are affected by micro-organisms could own. Viruses need a host/living cell to reproduce / include: nutrient cycling, food production, sewage treatment, replicate because they have no other life Be careful in use of the word “growth” as it can refer to the food poisoning, disease in living things, microbial attack on functions – they have no chemical processes of their own e.g. individual organism or to the growth of a population. everyday materials (helpful and harmful), antibiotics, and raw materials, energy and enzymes are supplied by host cell. resistance to antibiotics. Viruses are always PATHOGENS. Structure – virus Structure – fungi Structure – bacteria Nutrition – fungi 1. protein (coat) = capsid 1. sporangium 4 main different shapes – rod (bacillus), Hyphae: threads used for feeding / growth / spreading. 2. genetic material = 2. spores spherical (coccus), comma shaped Their function is: secretion of enzymes / extracellular nucleic acid / DNA / RNA 3. hyphae (vibrio) or spiral (spirillum). digestion / securing fungus to substrate / absorb water and/or (NOT chromosome) 4. mycelium (mass of nutrients and/or food. Absorbing nutrients allows further hyphae) 1. slime capsule (protection & prevents dehydration) 2. cell growth of the hyphae into new food. Hyphae branch out, and 1 wall (shape) 3. cell membrane (controls entry/exit of form a mycelium and spread to cover a large area. As the 2 1 1 substances) 4. cytoplasm (cell reactions occur here) 5. genetic hyphae grow, new sporangia are produced 2 2 material (genes control bacterium processes) 6. flagellum/a (reproduction). (movement) 1 Yeasts – are single celled fungi. 3 2 Mushrooms - are large fungi. 3 Viruses are NOT alive – exist 4 4 6 Fungi cause diseases that include thrush, only to reproduce. 5 ringworm, and athlete’s foot. No Brain Too Small BIOLOGY Why we get sick with viruses How viruses make us sick Antibiotics Reproduction Large numbers produced quickly Viruses reproduce in a living cell, and because they can make We take antibiotics to fight bacterial infections. Antibiotics are Structure Unable to recognise protein coat / new protein coat many hundreds of viruses inside each cell before it dies this based on natural compounds the fungi produce to compete formed / new antigen formed causes many more cells to die and organs to malfunction against bacteria for nutrients and space. Mutation DNA / RNA alters frequently / virus mutates quickly which leads to illness. Antibiotic resistance has occurred because of overuse or requiring new antibody / host cannot produce new antibodies Viral diseases - measles, mumps, flu, AIDS inappropriate use of antibiotics. quickly enough. Variation / mutations can occur in bacterial populations which Why we catch colds more than How bacteria make us sick may lead to antibiotic resistance, and may allow them to Bacterial reproduction doesn’t destroy living cells, but instead survive. The resistance is passed on to subsequent once? increases the number of bacteria so that the amount of toxin generations, so the antibiotics will no longer work. By finishing Proteins/antigens form the part of the virus that is recognised they excrete increases. It is the toxin which then causes the course of antibiotics more bacteria will be killed / less will by the immune system. Frequent mutations lead to different inflammation in parts of the body. survive. strains with different protein coats/antigens. These are not Bacterial diseases – meningitis, salmonella, TB Viruses cannot be killed by antibiotics. recognised by the immune system. Vaccines Culturing bacteria, fungi & viruses How bacteria can cause food Vaccines cause the body to produce specific* antibodies. Inoculate a sterile nutrient agar plate. Incubate sealed and poisoning A vaccine is a dead or weakened form, or even a fragment of a labelled, upside down in a warm place. Avoid sealing it air Bacteria reproduce on food if conditions allow growth. The microbe, that induces the person’s body to make antibodies in tight & incubating near body temperatures as this encourages bacteria release toxins into the food which can be a poison to advance, so it will respond quickly and destroy the microbes if the more harmful anaerobes and microbes that thrive in humans making them sick. they infect the body. Inactivated toxic compounds are used humans. Store upside down to avoid condensation falling on where these, rather than the micro-organism itself, cause the microbes. How disinfectants work illness eg tetanus. Fungi appear as fuzzy / furry / fluffy patches. Bacteria grow in Disinfectants kill / eliminate / destroy / inhibit growth of *Specific: The vaccine only works if the microorganism strain is colonies, and appear as shiny or greasy spots in a variety of harmful / pathogenic microorganisms / bacteria, reducing the the same as the immunity that has been built up. If a different colours. Plates should later be destroyed by burning them or chance of infection through food contamination / wounds / or strain or a new mutated form of the strain infects the individual, soaking in strong disinfectants. items / areas that present a high risk of infection (eg plates, the antibodies will not recognise the microorganism, and the Viruses can only be cultured (grown) in living cells eg fertilized chopping boards, kitchen areas, door handles etc). patient is likely to become ill. hens eggs. Antiseptics kill the microbes without killing our cells. Nutrient cycles – decomposers Uses of Fungi - yeast Terms Without decomposition, nutrients would not be available / Yeast cells make CO2 and alcohol (ethanol) when they carry saprophytic - feeds on dead/decomposing/decaying matter would run out / be all locked up in living animals and plants. out feeding or respiration (fermentation) - anaerobic respiration (saprophyte); no harm done –beneficial in a decomposing role Fungi and bacteria make nutrients available in usable form. of glucose. glucose → ethanol + carbon dioxide + energy decomposer - are organisms that consume dead organisms, Nitrogen fixing bacteria in root nodules and soil turn N2 from CO2 makes the dough rise / beer & wine bubble and ethanol and, in doing so, carry out the process of decomposition the air into usable nitrates (used by plants to make proteins) makes the beer or wine alcoholic. The release of CO2 and Fungi break down dead organic material containing carbon / ethanol is excretion as these are waste products to the yeast. parasitic - feeds on living organic matter / material / host nitrogen and use it to build their structures / release energy for Uses of bacteria (parasite): harmful respiration. The nutrients are recycled through the food chain Yoghurt / cheese is produced by the fermentation / respiration pathogen/pathogenic- disease causing microorganism and used as food by other organisms. The fungi excrete of bacteria added to milk. Respiration of the milk sugar lactose useable nutrients that plants can absorb from the soil and by bacteria produces lactic acid. The lactic acid lowers the pH aerobic bacteria – require oxygen for respiration store. Microbe respiration also releases CO2 necessary for of the milk allowing the milk (proteins) to curdle / precipitate as anaerobic bacteria – do not require oxygen for respiration photosynthesis. solid curds. No Brain Too Small BIOLOGY .
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