animal cloning

Question 1

Animal cloning can either occur,,,

Answer 1

Naturally or artificially

occurs naturally-

when an embryo splits during early stages of development

and develops into multiple embryos with the same genetic information.

Question 2

2 methods of artificially cloning animals?

Answer 2

Artificial embryo twinning

somatic cell nuclear transfer( SCNT)

Question 3

Artificial embryo twinning (cows):

Answer 3

1) egg cell extracted from cow and fertilised in a petri dish
2) Fertilised egg is left to divide at least once forming an embryo
3) individual cells from the embryo are separated and each is put into a separate petri dish, the individual cells each develop into an embryo.
4) Embryos implanted into cows ( surrogate mothers)

5) Embryos continue to develop inside surrogate mothers and eventually offspring are born.
- which are all genetically identical to each other.

Question 4

What is a somatic cell?

Answer 4

Any cell that isn’t a reproductive cell.

Question 5

Somatic cell nuclear transfer: (SCNT)

Answer 5

Involves 2 sheep:

1) somatic cell is taken from sheep A, nucleus is extracted and kept
2) An oocyte ( immature egg cell) is taken from sheep B, it’s nucleus is removed to form an enucleated oocyte.
3) Nucleus from sheep A is inserted into enucleated oocyte.
4) The nucleus and enucleated oocyte are fused together and stimulated to divide ( by electrofusion), an embryo is produced.
5) Embryo is implanted into a surrogate mother , and the lamb that is born is a clone of sheep A.

Question 6

Uses of animal cloning:

Answer 6

• research purposes ( e.g. in medicine when testing drugs in cloned animals)
• to save endangered animals from extinction by cloning individuals.
• used in agriculture by farmers to increase the number of animals with desirable characteristics to breed from.
• some animals are genetically modified to produce a useful substance, clones are made to have a lot of these animals producing a lot of useful substances.
• for cloned embryonic stem cells from young embryos- which help prevent diseases. If the embryonic stem cells are genetically identical to patient’s own cells it won’t be rejected by their immune system.

Question 7

Arguments for animal cloning ( 5 advantages):

Answer 7

1) Desirable genetic characteristics are always passed on to clones.
2) Infertile animals can be reproduced
3) Increasing population of endangered species helps to preserve biodiversity.
4) animals can be cloned at any time
5) provide new treatments for disease.

Question 8

Disadvantages of animal cloning ( 4 disadvantages)

Answer 8

1) Animal cloning is difficult, time consuming and expensive
2) no genetic variation in clones so may be undesirable genetic characteristics.
3) using cloned human embryos as a source of stem cells is controversial, some people think that destroying embryos after embryonic stem cells are harvested is destroying a human life. which is unethical.