Animal cloning: methods, uses and ethics

In a nutshell

Animals can be cloned via artificial embryo twinning or somatic cell nuclear transfer. Both of these methods can be used to produce animals with desirable features that have a wide range of uses in farming and medicine. Whilst these techniques have many advantages, they can be seen as unethical and therefore some people may be opposed to animal cloning.

Artificial clones

Animals can be artificially cloned via artificial embryo twinning and somatic cell nuclear transfer.

Artificial embryo twinning

This technique can be used to clone cows with desirable characteristics.

Example

The mother may have a high milk yield and the father may be known produce high milk yield daughters.

Biology; Cloning and biotechnology; KS5 Year 12; Animal cloning: methods, uses and ethics

1.	An egg cell is removed from a cow and fertilised in a Petri dish.
2.	The fertilised egg then divides into an embryo. Note: This occurs outside of a living organism so it is known as in vitro.
3.	The individual cells from the embryo are separated and put into individual Petri dishes. Each cell can then divide and develop normally into an embryo.
4.	The embryos are then implanted into surrogate mothers.
5.	The embryos continue to develop inside the surrogate mothers. This leads to genetically identical offspring eventually being born.

Somatic cell nuclear transfer

Biology; Cloning and biotechnology; KS5 Year 12; Animal cloning: methods, uses and ethics

1.	An immature egg cell (oocyte) is taken from sheep A and its nucleus is removed to form an enucleated oocyte.
2.	The nucleus is removed from a somatic cell (body cell) of sheep B.
3.	The nucleus from sheep B is put into the enucleated oocyte from sheep A.
4.	The nucleus and enucleated oocyte are fused together and stimulated to divide by electrofusion. This results in an embryo.
5.	The embryo can then be implanted into a surrogate mother.
6.	Eventually, a lamb that is genetically identical to sheep B is born.

Curiosity: During sexual reproduction, a fertilised egg can divide into genetically identical embryos. These will form identical twins and this is an example of natural animal cloning.

Uses of animal cloning

Use	Description
Research	Cloning can be used in drugs research as it allows new drugs to be tested on identical animals. This can rule out other variables, that arise from genetic differences, that may influence the effect of a drug.
Endangered species	Endangered species can be cloned to save them from extinction by producing new individuals in populations.
Agriculture	Farmers can clone animals with desirable characteristics to increase profits.
Therapeutics	Scientists can clone embryonic stem cells that can be used to replace damaged tissues in affected patients. These cells will be genetically identical to the patient, this means there is no risk of immune rejection.

Arguments for and against animal cloning

For	Against
Desirable characteristics will always be passed on clones.	The lack of genetic diversity can mean that a single disease could affect the whole population negatively.
Cloning endangered animals helps to preserve biodiversity.	Cloning of animals is difficult, expensive and very time-consuming.
Cloning of tissues can help treat diseases and improve the lives of many patients.	Using human embryos as a source of stem cells is very controversial as some people consider embryos a life. These embryos are often destroyed after the cells have been harvested which can be seen as unethical.