Topic 21

Question 1

genetic modification

Answer 1

the alteration of an organism’s genetic material by removing, changing or inserting individual genes

Question 2

bacteria modification to produce human proteins

Answer 2

1. human gene isolated by restriction enzymes - these recognize specific sequences of DNA and cut them at those points and leave these bits with ‘sticky ends’
2. plasmid remove from bacterium - plasmid cut open using same restrictive enzyme leaving complementary sticky ends
   3.human gene inserted into plasmid mixing together with DNA ligase. Joins sticky ends together to form recombinant plasmid
3. recombinant plasmid inserted to bacterium
4. modified bacterium multiplies producing human protein

Question 3

advantages of genetic modification

Answer 3

• herbicide and insect resistant plants have improved yields
• modified to grow in poor conditions
• crops with additional nutritional value could be valuable in places with not enough food

Question 4

disadvantages of genetic modification

Answer 4

• transplanted genes might be passed onto other organisms
• changing an organisms genes could cause unforeseen problems
• genetic modified crops can affect human health
• crops more expensive

Question 5

yeast in making biofuel

Answer 5

1. biofuels are made from biomass
2. biomass is processed to break down large carbohydrates into sugars
3. yeast breaks down these sugars to produce ethanol in aerobic respiration
4. carried out at a large scale in fermenters - ethanol collected, purified and used as biofuel

Question 6

pectinase in fruit juice production

Answer 6

1. pectin is a carbohydrate found in a plant cell well
2. pectinase is an enzyme that breaks down pectin - produced by bacteria and fungi to speed up fruit and veg decomposition
3. fruit juice manufacturers uses pectinase to break down the cell walls in fruit so the juice can be extracted more easily

Question 7

biological washing powders

Answer 7

• contain enzymes to break down stains in clothes
• lipases, amylases: digest carbohydrate based stains
• protease: protein based stains
• more effective at low temperatures (30 dgrs)

Question 8

lactose free milk

Answer 8

1. lactose intolerant people can’t digest lactose because they don’t produce the enzyme lactase
2. lactase breaks down glucose into glucose and galactose to make lactose free milk
   - to make it: lactase is immobilised by encasing it in alginate beads - milk passed over to be broken down

Question 9

conditions for fermenters

Answer 9

• nutrients provided in culture medium
• PH monitored: optimum level by adding acid or alkali so enzymes work more efficiently
• temperature: heat released when organisms respire so cooling jacket so that it doesn’t get so hot and enzymes denature
• oxygen: needed for respiration to increase product yield and to provide energy for growth
• paddles to circulate the medium around the vessel increasing product yield because organisms always have access to nutrients for growth. this also keeps even temp and pH
• CO2 and other materials removed from the exhaust to have optimum conditions for growth
• vessels sterilised between uses with superheated steam to kill unwanted microbes - less competition and no contamination increasing product yeild