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B6- under the microscope… Bacteria and Virus • Can be cultured using an aseptic technique • Viruses have a protein coat surrounding a strand of genetic material. They only reproduce in living cells, only attack specific cells. Reproduction of virus Bacteria • • • • • • • • Flagellum for movement Cell wall for shape DNA control function 4 shapes…spherical, rod, spiral, curved rods Reproduce assexually called binary fission Survive in a range of habitats Exploit a range of energy sources Rapid growth can cause food to spoil Harmful microbes • Diseases can be transferred through food, water, contact and airborne droplets • The enter the body, grow rapidly (the incubation period) produce toxins and then symptoms appear. • Antibiotics and antivirals can control the disease but overuse can render them ineffective and give rise to bacteria that are resistance to antibiotics through natural selection • To avoid this you must only prescribe when necessary and complete the dose Natural Disasters • Damage the sewer systems & water supplies • Damage to electrical supplied and rapid food decay • Displacement of people • Disruption to services (eg transport & emergency services) Discoveries • Pasteur- germ theory • Lister- Antiseptics • Fleming- penicillin • You need to know what they discovered and an understanding of the method(s) they used Useful Microbes • Yogurt (sterilise equipment, pasteurise, incubation, sampling, flavours/colours). Use of lactobacillus bacteria that breaks down lactose into lactic acid- this gives it the wobbly consistency • Brewing- fermentation is the anaerobic respiration of yeast to produce alcohol… Glucose->ethanol + carbon dioxide C2H12O6 -> 2C2H5OH + 2CO2 Brewing Continued • The main stages of brewing beer are… extracting sugar from the source, add yeast, prevent entry of air, clarfiying/clearing, drawing off, pasteurising, casking and or bottling • The process must be done in absence of oxygen to create an environment for anaerobic respiration • Pasteurisation is the sterilisation of product by taking it to a high temperature momentarily to kill any unwanted bacteria • Distillation can make your beer stronger but is illegal to do so without a license • Different yeasts can tolerate different levels of alcohol before they die : Biofuels • To make biofuels you need a large amount of biomass generated by fast growing trees or by transferring the energy of biomass by fermenting them with bacteria of yeast. • Advantages are- alternative to fossil fuels, carbon neutral, no particulates • If they are burnt at the same rate as they are being produced and no other crop is being cleared to grow crops for biofuels there will be no increase is greenhouse gases. • Disadvantages- potential habitat loss and extinction of species Biogas • Made of methane, carbon dioxide and traces of other gases. If there is less that 10% methane it is explosive. • Can be produced on a large scale using a continuous flow method • Can be used to generate electricity, produce hot water or fuel for vehicles • Biogas is made by fermenting waste and so is susceptable to high & low temperatures Gasohol • A mixture of alcohol and petrol • Used in cars in Brazil • Good for countries that have lots of sugar and small oil reserves Life in Soil • Sandy soil and clay soil have difference particle sizes. Loam is a mixture of the two • Humus is soil made of decomposing matter, rich in minerals. • Particle size effect air and water content. • Soil needs as so the microscopic life can respire. If soil has too much water it is impossible for respiration to take place. Some water is essential however for both plants and animals in the soil • Aerating and draining can made the water and oxygen levels. • It is also important to mix up the layers and neutralise the soil Life in soil • Earthworms burying organic matter, aerate, drain, mix up layers and neutralise the soil (WOW) • Charles Darwin was the scientist who discovered they unique important in the life of soil Life in Water • Advantages- support, good for waste disposal, constant water supply, less variation in temp • Disadvantages- need to regulate water content of the body (i.e contractile vacuoles), resistance to you movement • Photosynthesis of plants at depth depends on light, temperature and mineral content of the water • The amount of phytoplankton and zooplankton fluctuate over seasons (you will need to interpret data on this • Grazing food webs- start with a living producer • Marine snow- decomposing matter falling form the suface Contractile Vacuoles Eutrophication • • • • • • • • Fertiliser runs into the sea/lake Rapid growth of algae Plants in the dark die Rapid growth of bacteria Uses up all oxygen Fish die This is an accumulitive long term effect. Other similar chemical include pesticides (DDT on whales) due to bioaccumilation Enzymes (again) • Amylase, lipase, protease, can be used as biological washing powder at moderate temperatures • Sucrose can be broken down to a sweeter glucose or fructose by the enzyme sucrase to make artificial sweeteners • Lactose intollerance means the enzyme lactase does exist so the lactose ferments in the body causing diarrhoea and wind Immobilising enzymes • Mix the enzyme in an alginate and drop the mixture into calcium chloride. • Enzyme can be used over and over without being contaminated • Can be used in a continuous flow process • These are used to make lactose free products. • Immobilised lactose converts lactose to glucose and galactose Genetic Engineering (again) • Identification of desired gene in one organism • Removal of gene from DNA • Cutting open the DNA in another organismrestriction enzyme • Inserting the new gene into the DNA- ligase enzyme • Transgenic organism can be cloned to produce identical copies • Gene works in transgenic organism Making Insulin • The gene for producing human insulin is cut out of human DNA • A loop of bacterial DNA is cut open • The insulin gene is inserted into the loop • The loop is inserted into the bacterium • The bacteria are able to produce insulin • Transgenic bacteria are cultured by cloning • Large quantities of insulin are harvested