Topic 6c- Selective breeding / genetic engineering / cloning

Question 1

What is selective breeding?

Answer 1

Selective breeding is when humans artificially select plants or animals with desired traits before breeding them in order to make specific genes and therefore characteristics remain within the population

Question 2

Describe the process of selective breeding

Answer 2

1. From existing livestock, ones with specific desired characteristics are selected
2. They are then bred with eachother
3. The best of their offspring are then taken and bred together
4. This is continued for multiple generations until all the offspring have this desirable characteristic

Question 3

What are problems with selective breeding?

Answer 3

• Selective breeding results in a small gene pool
• This results in inbreeding which can cause health problems as there are greater chances of organisms inheriting harmful genetic defects
• There can be serious problems if a new disease appears as the animals don’t have much variation in their population

Question 4

What are some examples of what an organism might be selectively bred for?

Answer 4

• animals to produce more meat or milk
• crops with resistance to disease
• decorative plants with big or unusual flowers

Question 5

What is genetic engineering?

Answer 5

To transfer a desirable characteristic from one organism’s genome into another organism

Question 6

How does genetic engineering work?

Answer 6

1. A useful gene is isolated (cut) from one organism’s genome using enzymes and is inserted into a vector.
2. The vector is usually a virus or a bacterial plasmid depending on the type of organism the gene is being transferred to.
3. When the vector is introduced to the target organism, the useful gene is inserted into the cell(s).

Question 7

How can the human insulin gene be inserted into bacteria to produce insulin?

Answer 7

1. The insulin gene is cut out of human DNA using enzymes
2. The same enzymes are then used to used to cut the bacterial DNA and different enzymes used to insert the human gene
3. The bacteria are then allowed to multiply
4. The insulin produced by the bacteria will then be purified and used to treat people with diabetes

Question 8

What are some examples of what scientists use genetic engineering for?

Answer 8

1. Bacteria are genetically modified to produce insulin
2. GM (genetically modified) crops
3. Sheep have been genetically engineered to produce substances like drugs in their milk that can be used to treat human diseases
4. Scientists are researching genetic modification treatments for inherited faulty genes

Question 9

What are some issues surrounding genetic engineering?

Answer 9

• Ethical issues
• Worries that changing a person’s genes might accidentally cause unplanned problems

Question 10

What are some concerns about GM crops?

Answer 10

• Some people say that growing GM crops would affect the number of wild flowers abd therefore the population of insects that live round the crops
• Not everyone is convinced that GM crops are safe and that we might not fully understand the effects of eating them (although there is no more risk than eating normal foods)
• Concern that the transplanted genes may get out into the natural environment (e.g. herbicide resistance being picked up by a weed)

Question 11

What are the benefits of GM crops?

Answer 11

• Characteristics chosen for GM crops increase yield, therefore feeding more people
• People living in developing nations often lack important nutrients in their diets and so GM crops could be used to generate nutrients that they are missing

Question 12

What is cloning?

Answer 12

Cloning is creating a genetically identiacal copy of an organism.

Question 13

In what ways can plants be cloned? How do they work?

Answer 13

Tissue culture

• a few plant cells are put into a growth medium with hormones
• they grow into clones of the parent plant

Cuttings

• gardeners take cuttings from parent plants
• the cuttings are then planted to produce clones of the parent plant
• this is a cheaper, and older method than tissue culture

Question 14

Why might scientists use tissue culture?

Answer 14

To preserve rare plants that are hard to reproduce naturally

Question 15

What can be done to produce clones of animals?

Answer 15

• Embryo transplants
• Adult cell cloning

Question 16

How would farmers use embro transplants to clone their best bull and cow?

Answer 16

1. Sperm cells are taken from the best bull and egg cells from the cow
2. The sperm cells then artificially fertilise the egg
3. The embryo that is developed is split many times to form clones before any cells are specialised
4. These cloned embryos are then transplanted into lots of other cows
5. The cows that are birthed from the cows are genetically identical to eachother

Question 17

How does adult cell cloning work?

Answer 17

1. An egg cell is taken and the nucleus is removed from it
2. An adult body cell is taken, and its nucleus is removed before being insereted into the egg cell
3. The egg is then stimulated by an electric shock causing it to divide like a normal embryo
4. When the embryo is slightly more developed it is implanted into the womb of a surrogate mother
5. Here the embryo develops into a clone of the original adult body cell as it has the same genetic information
   (this is how Dolly the sheep was created)

Question 18

What are the benefits of cloning?

Answer 18

• quickly generates lots of ideal offspring which can benefit farmers
• studying animal clones can lead to a greater understanding of the development of the embryo and of aging and age related disorders
• it can be used to help preserve endangered species

Question 19

What are the concerns of cloning?

Answer 19

• cloning results in a “reduced gene pool” making a population more at risk of dying out due to one disease
• it’s possible that cloned animals might not be as healthy as normal ones
• ethical worries over cloning humans in the future- the clone has no say in whether it wants to be a clone or not etc.