6.4.3(artificial clones in animals)

Name the 2 main classes of stem cells

• Totipotent cells

• Pluripotent cells

Describe what is meant totipotent cells

• Cells which are able to divide and differentiate into all types of cells

Describe the uses of reproductive cloning

• Can be used to produce large numbers of genitically identical animals:

  • Elite farm animals can be produced by selective breeding or genetic modification

  • Can produce genitically modified animals with unusual characteristics

Name the 2 main techniques to achieve reproductive cloing

• Embryo splitting

• Somatic cell nuclear transfer(SCNT)

Describe the produced embryo splitting

1. A zygote is created using IVF

2. The zygote is allowed to divide by mitosis to form a small ball of cells

3. The cells are seperated and allowed to continue dividing

4. Each small mass of cells is placed in a uterus of a surrogate mother

Describe the use of embryo splitting

• Used to clone elite farm animals

• Used to clone animals for scientific research

Describe the process of Somatic cell nuclear transfer

1. An egg cell is obtained and its nucleus is removed - enucleation

2. A normal body cell(somatic cell) from the adult to be cloned is isolated and may have the nucleus removed

3. The complete adult somatic cell or its nucleus is fused with the empty egg cell by applying an electric shock

4. The shock also triggers the egg cell to start developing, as though it has just been fertilised

5. The cell undergoes mitosis to produce a small ball of cells

6. The young embryo is placed into the uterus of a surrogate mother

Describe what is meant by non-reproductive cloning

• The production of cloned cells and tissues for other purposes than reproduction

Name one method of non-reproductive cloning

• Therapeutic cloning

Describe what is meant by therapeutic cloning

• The use of stem cells to correct diseases and other health problems that someone many encounter

Give 3 examples of uses of therapeutic cloning

• Repair damage to spinal cord

• Restore production of insulin in the pancreas

• Replaced whole organs that are diseased

Describe why a sample is taken from a patient to be cloned instead of using another persons sample

• Because it is genetically identical to all other cells in the body

• Will not be rejected

Describe the arguments for artificial cloning in animals

• Desirable characteristics always passed on

• Infertile animals can be reproduced

• Increase population of endangered species - preserving biodiversity

• Animals can be cloned at any time

• Can be used for testing medicinal drugs on tissue instead of animals

• can produce cells which are genetically identical to the donor for use in repairing damage caused

Describe the arguments against artificial cloning in animals

• Very difficult, time consuming and expensive

• No genetic variability - all susceptible to same disease

• Early evidence thought that clones may not live as long - unethical

• Using cloned human stem cells is controversial