Learning outcomes:
describe the process of micropropagation (tissue culture) in which small pieces of plants (explants) are grown in vitro using nutrient media
understand how micropropagation can be used to produce commercial quantities of identical plants (clones) with desirable characteristics
describe the stages in the production of cloned mammals involving the introduction of a diploid nucleus from a mature cell into an enucleated egg cell, illustrated by Dolly the sheep
evaluate the potential for using cloned transgenic animals, for example to produce commercial quantities of human antibodies or organs for transplantation.
Cloning is used to make many copies of a single individual. Usually the individual has a very desirable phenotype and has often been produced at the end of a selective breeding or GE programme.

Cloning in plants:

The easiest way to clone a plant is to take a cutting or a graft (see earlier). However, micropropagation (tissue culture) can be used in large-scale cloning programmes.

Micropropagation - small pieces of plants (explants) are grown in a Petri dish on nutrient medium. Samples of the culture can be taken off and grown separately. If the right hormones are added the culture will turn into a miniature plant (a plantlet). This can be done on a huge scale to produce 1000s of plantlets from a single culture.

Cloning in animals:

1. Take an embryonic cell
2. Remove it’s nucleus (enucleate it)
3. Replace with the nucleus from an adult cell (from the animal you want to clone)
4. The embryonic cell grows into an embryo clone of the adult from which the donor nucleus came

This process was used to create Dolly the sheep. Cloning can be used beneficially in agriculture to increase the yield of crop plants. However, cloning genetically engineered animals organisms allows us to mass-produce very useful organisms e.g. the E. coli bacterium that makes human insulin has been cloned many times. Now all diabetics have access to human insulin.