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A2 biology 2.2

OCR biology - biotechnology

Define biotechnology The industrial use of living organisms and biological processes to improve agriculture, food science, medicine, animal husbandry, industry, waste treatment
How is biotechnology used in agriculture? GM crops, micropropagation
How is biotechnology used in food science? Cheese production: lactobacillus bacteria respire lactose anaerobically -> lactic acid. Quorn (MYCOPROTEIN) production: fungus Fusarium Venenatum. Wine production: yeast respire glucose + fructose in grapes anaerobically -> ethanol. GM food crops e.g. Gol
How is biotechnology used in medicine? gene therapy, drug-producing microorganisms e.g. Penicillium produces antibiotics, GM
How is biotechnology used in industry? Enzyme-producing microorganisms (e.g. A. niger fungus produces pectinase naturally, used for fruit juice extraction) and bio-gas production by methanogenic bacteria grown on sewage
How is biotechnology used in waste water treatment? Microorganisms are grown on waste water, feed on waste matter, no longer harmful
Why are microorgniams used in biotechnology? Reproduce rapidly (generation time: 30 mins), large yield, can be GMed easily, grown on waste matter (cheaper FEEDSTOCK), grown in fermenters anywhere in the world/ don't take up much space, products purer than those produced by chemical processes
Define culture and closed culture Culture - growth of microorganisms on nutrient medium (broth/agar), pure=1 species, mixed =several species. Closed culture - self-contained, conditions are fixed, no materials/ organisms are added or removed
What is the standard growth curve? Models the population growth of a small group of organisms in a fresh, closed culture. Lag, log, stationary and decline phases
Describe the lag phase Population size increases slowly, organisms are adjusting to surroundings (taking in water, activating certain genes, synthesising enzymes)
Describe the log phase - what affects the length of this phase Population size doubles per generation because each individual has sufficient space and nutrients to reproduce, generation time can be as short as 30 mins. depends on how quickly organisms reproduce + take up nutrients/ space
Describe the stationary phase Reproduction rate = death rate, because nutrient levels decrease and waste materials accumulate (metabolites e.g. CO2)
Describe the decline phase Death rate exceeds reproduction rate due to nutrient exhaustion and high concentration of waste materials, eventually all organisms die
What are primary metabolites? Substances produced by organism as part of normal growth/ METABOLISM (amino acids, nucleic acids, lactate, ethanol, proteins), produced by all organisms all the time so production matches population growth of organism
What are secondary metabolites? Produced by organism not as part of normal growth/ metabolism, only produced by some organisms, production starts after main growth phase (metabolic activity growth/reproduction) so doesn't match population growth. Antibiotics in stationary phase
What is batch culture? Microorganism starter culture + certain quantity of nutrient, closed culture, fermenter is drained. Standard growth curve, pop growth decreases. 2dry metabolites - stress in stationary/ decline phase. Less efficient, contamination =only 1 batch discarded
What is continuous culture? Nutrients are added/ wastes are removed at regular intervals, open culture, reservoir. Always log phase. Primary metabolites/ microorganisms. More efficient - fermenter is always in use. Contamination - large volume of product lost, expensive
How can you adjust growing conditions to maximise the yield? Temperature: thermostatically-controlled water jacket removes heat from respiration, could denature enzymes. Nutrients: glucose, amino acids, vit/mins. Time of adding. High [O2] for aerobic respiration . pH buffers, probe, denaturation. Paddle- mix evenly
Draw and label a fermenter Inlet for steam (disinfectant), inlet for nutrients, inlet for sterile air, inlet for water jacket, water jacket, outlet for water jacket, motor (rotates paddle), paddle, stainless steel, outlet for product with tap, pressure vent, electronic probe
Define downstream processing Separation and purification of the product of large scale fermenters e.g. filtration, centrifugation
Define asepsis and aseptic technique Asepsis - absence of unwanted microorganisms (contaminants). Aseptic technique - measures taken to prevent culture/ product being contaminated by unwanted microorganisms
Why is the lack of asepsis a problem? Contaminants could: compete with culture microorganisms for space and nutrients, reduce growth rate, reduce product yield, release toxic chemicals, spoil product (dangerous for medicinal/ food products), kill culture microorganisms
How is asepsis achieved at a small/ starter-culture scale? Regularly disinfect work benches, wear gloves, keep air flowing through fume cupboard, sterilise all apparatus before use with UV/flame, flame the necks of containers, keep lids on culture
How is asepsis achieved at a large scale? Use polished stainless steel fermenters to prevent microorganisms form sticking, sterilise air and nutrients, disinfect/ steam clean pipes and fermenter when not in use, fit all inlets and outlets with fine filters
What are immobilised enzymes + 4 methods? Enzymes are held separately from the reaction mixture, attached to an insoluble material: adsorption, covalent bonding, entrapment, microspheres
Describe adsorption Enzymes bind to a porous support (clay, resin, carbon, glass bead) by hydrophobic interactions/ ionic bonds. High reaction rate provided active sites are on display, not guaranteed. WEak bonding = leakage
Describe microspheres Enzymes are trapped inside spheres of partially permeable membrane e.g. chitosan-alginate, active site is unchanged, substrate and reactant are small enough to diffuse across membrane
Describe entrapment Enzymes are trapped inside cellulose fibres/ sodium alginate beads/ silica gel. Active site is unchanged. Low reaction rate as active site is poorly accessible by substrate, which has to diffuse through trapping barrier
Describe covalent bonding Enzymes bind to a support (cellulose) by covalent bonds, aided by a cross-linking agent e.g. glutaraldehyde, doesn't immobilise much enzyme but strong bonds = no leakage
What are the advantages of immobilising enzymes? Low costs of downstream processing/ enzymes absent from product, enzymes are more stable so are less likely to be denatured by temperature/pH changes, enzymes are immediately available for reuse, long-lasting
What are the disadvantages of immobilising enzymes? Preparation is time consuming and costly, enzyme catalysis is less efficient e.g. entrapment, contamination is costly, leakage may occur
How would you make lactose-free milk? Mix lactase and sodium alginate solution, add droplets to CaCl2 solution forming gel beads containing immobilised lactase, pour milk through a column packed with beads, milk travels slowly allowing time for enzyme catalysis
Compare the use of immobilised enzymes and immobilised cells Immobilised cells: cheaper/ quicker to prepare, enzymes don't leak. Immobilised enzymes: more efficient enzyme catalysis, product isn't contaminated/ used up by cells
Define metabolite A product of an enzyme-catalysed reaction in cells that can enter subsequent reactions
What is fed-batch culture? Limited amounts of nutrients are added at regular intervals to keep the culture alive and prolong the stationary phase, used to produce secondary metabolites
Why is glucose added to a culture? Carbon source, respiratory substrate
What are the disadvantages of using microorganisms in biotechnology? Fermenters can become contaminated, high cost of downstream processing
Created by: 11043



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