21. Biotechnology and genetic modification

Question 1

What type of organism is useful in biotech/genetic modification?

Answer 1

bacteria

Question 2

What are bacteria useful in and why?

Answer 2

useful in biotechnology and genetic modification
rapid reproduction rate and ability to make complex molecules

Question 3

What are other reasons bacteria are useful in biotechnology and GM?

Answer 3

few ethical concerns over their manipulation and growth
presence of plasmids

Question 4

How is yeast’s anaerobic respiration used to produce ethanol (for biofuels)?

Answer 4

1. Sugars from plants eg sugar cane and wheat are the raw material needed (also possible to use the cellulose from plant cell walls, if it is first digested with enzymes)
2. The sugars mixed with yeast and water, kept warm in an oxygen-free atmosphere
3. It takes a few days for significant amounts of ethanol to be produced

Question 5

How is yeast’s anaerobic respiration used to make bread?

Answer 5

1. Dough is mixed with yeast, also adds air to the dough and yeast mixture
2. Yeast initially releases energy by aerobic respiration, producing carbon dioxide (and water), which causes the bread to rise
3. Once oxygen in dough is used up, anaerobic respiration can take place
4. The carbon dioxide produced continues to cause the bread to rise
5. Ethanol released into the dough boils away when the bread is baked in the oven

Question 6

How is ethanol turned into a biofuel?

Answer 6

You can use ethanol directly as a fuel, but usually it is mixed with petrol to make a biofuel

Question 7

Describe the use of pectinase in fruit juice
production

Answer 7

Pectin: protein that holds cell walls together. Pectinase: enzyme that breaks down the pectin molecules. This causes the cell walls to fall apart and opening up the cells to allow juice to be extracted more easily + juice looks clearer

Question 8

Describe the use of biological washing powders that contain enzymes.

Answer 8

‘Biological’ washing powders contain enzymes to digest (break down) the substances in fabric stains

Question 9

Explain the use of lactase to produce lactose-free milk

Answer 9

1. lactase mixed with an alginate gel, making alginate beads that immobilise the enzyme
2. by immobilising the lactase, it is possible to use it repeatedly because it is not washed away with the product
3. milk is passed through a mesh, containing the immobilised enzyme of alginate beads, for several cycles until no more lactose is detected

Question 10

Investigate the effectiveness of biological detergent at different temperatures.

Answer 10

1. get 5 pieces of white cloth all stained with the same amount of egg yolk
2. measure approximate area in cm3 covered by the stain using quadrant method
3. take 5 beakers
4. make up a mixture of washing powder and water 5. add mixture to each of the beakers until they are 3/4 full
5. place each beaker in a water bath at a different temperature
6. place one piece of stained cloth in each beaker, agitate with a stirring rod, and leave for 30 minutes
7. take the cloths out, record your observations
8. measure the approximate area in cm3 covered by the stain using the quadrant method, calculate the percentage change in area of the stain

Question 11

Label a fermenter

Answer 11

Question 12

In a fermenter, which conditions are controlled and why?

Answer 12

Maintain optimal temp and pH for fast reproduction, can be monitored by probes placed in mixture.
Sufficient nutrients and oxygen supply to fuel the growth. Any waste products of respiration, such as CO2, must be removed from fermenter.

Question 13

Importance of sterilisation in a fermenter

Answer 13

Any air or substance entering the fermenter must be sterilised. Sterilisation will kill any other microorganisms before they enter the fermenter: if not done, unwanted microorganisms might grow, reducing output of the desired product/ contaminating it with potentially toxic substances

Question 14

What can fermenters be used for?

Answer 14

the large-scale production of useful products by bacteria and fungi, including insulin, penicillin and mycoprotein

Question 15

What is genetic modification?

Answer 15

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

Question 16

Outline the process of genetic modification using
bacterial production of a human protein.

Answer 16

1. Isolation of the section of DNA that makes up the required human gene. Use restriction enzymes which form
   sticky ends
2. Cutting of bacterial plasmid DNA with the same restriction enzymes, forming
   complementary sticky ends
3. Insertion of human DNA into bacterial plasmid DNA. Use DNA ligase to form a
   recombinant plasmid
4. Insertion of recombinant plasmids into bacteria
5. Multiplication of bacteria containing recombinant plasmids
6. Expression in bacteria of the human gene to
   make the human protein

Question 17

Outline examples of genetic modification

Answer 17

• insertion of human genes into bacteria to produce human proteins, eg insulin. Advantages: reduces need to use insulin extracted from animals + tolerated better by people with diabetes
• insertion of genes into crop plants to confer resistance to herbicides/insect pests
• insertion of genes into crop plants to improve nutritional qualities, like more vitamins and amino acids

Question 18

Discuss the advantages and disadvantages of genetically modifying crops of soya.

Answer 18

herbicide-resistant soybean
advantages:
* herbicide can be used where the herbicide-resistant plants are growing
* herbicide-resistant plants are not killed but the weeds are
* farmers can reduce amount of herbicide they use
* reduced competition with weeds increases the crop yield
disadvantages:
* these plants are not resistant to other herbicides, so they are only useful where the particular herbicide is used

Question 19

Discuss the advantages and disadvantages of genetically modifying crops of maize.

Answer 19

Bt corn is maize that contains the gene for insect resistance from a soil bacterium (Bt).
Advantages:
* Protein produced by Bt is used as an insecticide, is efficient, targets some insects but not others, does not affect mammals, fish or birds.
Disadvantages:
* gene may pass into other plant species which would gain resistance to insect pests, becoming ‘super weeds’ that would be difficult to control
* Bt protein may harm other insects that are not pests and which are an essential part of a food chain

Question 20

Discuss the advantages and disadvantages of genetically modifying crops of rice.

Answer 20

Golden rice: genetically modified strain of rice that produces extra beta-carotene in its grains
Advantages:
* makes a significant contribution to the diet of anyone who eats it
* fewer people suffering vitamin A deficiency
Disadvantages:
* its use may lead to people and governments not properly recognising the need for a balanced diet
* a more varied diet, including vegetables such as carrots (which also contain beta-carotene), could be a better solution