B3 Topic 3

• Rapid reproduction (20 mins) by asexual - clones
• Not all pathogenic so can eat
• V. small - little space required
• Easy to culture - not high temp. + simple nutritional needs
• Genetically modify

• Temp. controlled with temp. probe + cooling jacket
• Optimum temp. for binary fission - fast production - reduce cost
• pH controlled by pH probe and acid/alkali added
• Optimum pH to avoid denatured proteins
• Reduced oxygen - anaerobic respiration
• Nutrients steamed to avoid contamination - avoid competition for nutrients + space - yield decreased/product go off/toxic product

• Wrapping solid sucrose in chocolate + invertase
• Sucrose digested by invertase (over 2-4 weeks) into fructose + glucose
• Fructose is much sweeter than sucrose
• Glucose/fructose syrup (invert sugar) used in sweets + cakes as v. sweet so less used than sucrose so cheaper

• Need: milk
• Microorg: bacteria (Lactobacilli)
• Process: anaerobic respiration (lactose --> lactic acid + energy)
• Produce in fermenter (no air/O2, 35-40 degrees, sterile)

Why does milk become thick?

• Lactic acid from anaerobic respiration decreases pH (7 --> 4)
• Proteins in milk denature and clump together = thickened milk = yoghurt
• then add fruit/ flavour/colour

Need

• Pasteurised cows milk (contains lactose)
• Enzyme lactase

What happens?

• Lactase digests lactose into glucose and galactose
• In 40 degrees fermenter for a few hours
• Test for glucose  - check reaction occured
• Lactose free milk for lactose intolerent people - prevent them having diarrrhoea + upset intestines

• Want to keep enzyme in industry to save costs
• Ensures product not contaminated with enzyme

How?

• Wrap enzyme in alginate jelly
• Trap enzyme but allow substrate in to form ESC + reaction to occur
• At end filter out enzyme alginate balls

Adv.

• Decreased cost
• No contamination
• Protect enzyme from pH change + high temp. so does not denature as quickly

Other Immobilising Methods

• Attach to solid e.g. clay
• Separate by membrane

• Crush fruit - release juice from cells
• More juice in cell walls (cellulose + pectin) + retains juice
• So to increase juice production digest cell walls
• Pectinase to digest pectin
• Cellulase to digest cellulose
• Also create clear fruit juice (cloudy = cell walls in juice)
• Can immobilise enzymes to decrease cost

Microorg: fungi - blue cheese

Enzyme: chymosin - originally  from calves stomach, now produced by GM bacteria with chymosin gene - vegetarian friendly - no calves killed + unlimited supply

Reaction: milk --> curds + whey

• Curds = solid - coagulated protein - press/age/flavour --> cheese
• Whey = liquid - remove

• Enzymes + detergent
  • Pasta = starch --> amylase + maltase --> glucose
  • Cheese = lipids --> lipase --> fatty acids + glycerol
  • Bacon = protein --> protease --> amino acids
• Products are small and soluble so dissolve in water + leave tablecloth clean
• Run wash at 30-40 degrees - prevent enzymes denaturing (loss of active site)
• Enzymes from bacteria

• Greenhouses - controlled light + conditions e.g. high temp.
• GM - animals + plants
• Fertilisers in soil - min. ions e.g. Mg for chlorophyll, NO3 for proteins
• Pesticides + insecticides + fungicide - kill and increase crop
• Selective breeding - deliberately mating best animals/plants - select offspring + repeat many times
• Biological control - uses knowledge of predator and prey e.g. ladybirds eat greenfly

• Human insulin gene cut out of chromosome using restriction enzyme creating sticky ends
• Plasmid from bacterium opened using same restriction enzyme - complementary sticky ends
• Gene inserted into plasmid using DNA ligase to join sticky ends with hydrogen bonds forming recombinant plasmid
• Recombinant plasmid inserted into bacterium by transformation
• Protein synthesis occurs producing human insulin in bacterium

• Extract plasmid + cut open with restriction enzyme leaving sticky ends
• Cut out herbicide resistant gene from naturally resistant plant using same restriction enzyme
• Join complementary sticky ends with hydrogen bonds using DNA ligase = recombinant plasmid
• Transformation - insert plasmid back into Agrobacterium tumefaciens
• Plant to GM - create leaf discs + place in liquid containing Agrobacterium which infects plant cells + introduces herbicide resistance gene into plant DNA
• Grow leaf discs on agar with plant hormones (auxins + cytokinins) - cells divide by mitosis - grow shoots and roots --> plantlet
• Grow plantlet in sterile soil --> plant
• Test if GM worked - spray herbicide on plant - lives GM worked/dies GM failed

Advantages

• Health benefits for humans
• Longer lasting crops e.g. tomatoes
• Grow in adverse conditions e.g. GM to tolerate drought
• Increased yield = decreased cost of food
• Increased nutritional content e.g. golden rice = rice with vit. A (decrease blindness)
• Clone GM plants (quicker + cheaper than GM each time)

Disadvantages

• Expensive + long time to GM
• Yield may not increase, may decrease if wrong conditions
• Decreased Biodiversity
• Increase herbicide use = decrease weeds which will affect food chain
• Unknown health effects e.g. allergies
• Accidental transfer of new genes to other plants
• Cannot use in organic farming/people who are anti GM crops

Bacillus thuringensis = bacterium that has a gene = ICP - toxic to insects when eaten

• Cut out ICP gene from Bt with restriction creating sticky ends
• Remove plasmid from Agrobacterium - cut open with same restriction enzyme - complementary sticky ends
• Insert ICP gene into plasmid, use DNA ligase, H bonds form = recombinant plasmid
• Transformation - plasmid into Agrobacterium
• Infect plant cells with Agrobacterium + grow on agar --> plantlet --> grow in soil
• Test if GM worked - put insect on GM plant to eat it - dies = worked/ lives = failed

• Increased yield as not eaten by insects - decreased land used for crops
• Increased profit in farming
• could decrease food cost
• No crop damage by insects (better quality)
• Decreased insecticide/herbicide use
• Decreased insecticide/herbicide residue on food
• specific to insects - less impact on food chain (decreased bioaccumulation - increased level in each trophic level)

• Insects may become resistant
• Impact on food chain
• Impact on pollination
• Decrease biodiversity
• Unknown health effects to humans
• Costly
• Gene transfer to other crops
• Cannot use in organic farming

Ethanol - anaerobic digestion of plant matter or waste, Biogas - H2 + CH4 + CO2 - produce electricity

Advantages

• Carbon neutral
• Use waste products
• Not produce SO2 - acid rain
• Cheap
• Renewable fuel - conserving fossil fuel

Disadvantages

• Lots of land - decreased food
• Decreased biodiversity
• Releases CO2 on burning
• Difficult to transport
• Not widely available