Cloning Mammals
Embryo cloning
- It is possible to clone animals using embryo transplants
- For example, if a farmer wants the best cattle, they must first create an offspring from the best bull and best cow, and then clone this offspring to create many genetically identical copies (clones)
- This process is known as embryo cloning and is achieved in the following way:
- Egg cells from the best cow are artificially fertilised using sperm cells taken from the best bull
- This forms an embryo
- The developing animal embryo is then split apart many times before the cells of the embryo become specialised
- This forms many separate embryos that are genetically identical
- These cloned embryos are then transplanted into host mothers
- The calves born from these host mothers are all genetically identical
Embryo cloning
Adult cell cloning
- Adult cell cloning is achieved in the following way:
- The nucleus is removed from an unfertilised egg cell
- The nucleus from an adult body cell, such as a skin cell, is inserted into the egg cell
- A very small electric shock stimulates the egg cell to divide (by mitosis) to form an embryo
- These embryo cells contain the same genetic information as the adult skin cell
- When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female (known as the surrogate mother) to continue its development until birth
- This process was used to create the first clone (exact genetic copy) of a mammal in 1996
- Scientists in Scotland successfully cloned an adult female sheep
- The clone was called Dolly
Adult cell cloning: the cloning technique used to produce the first cloned mammal, Dolly the sheep
Benefits & Risks of Cloning Table
