Cloning: Answers

Describe how tissue culture can be carried out to produce a large number of genetically identical plants?

To produce a large number of cloned plants using tissue culture, you would first scrape off tiny pieces of tissue (explants) from the parent plant and place these in a petri dish containing sterile agar jelly, nutrients and plant hormones. The explants will grow and develop into small plants (plantlets) and when these are big enough, they can be transferred to compost. The plants produced are genetically identical (clones) of the original parent plant.

Why might somebody want to produce large numbers of genetically identical plants?

If the parent plant has favourable characteristics (such as large fruit), a gardener or farmer may want to create more plants with this characteristic. Cloning using tissue culture is a quick and cheap method of making a large number of plants with this favourable characteristic. It also has the advantage that you don’t need to wait for the right time of year in which the plant is fertile - it can be carried out all year around.

Describe how adult cell cloning can produce a cloned sheep.

A nucleus is extracted from the body cell of the sheep that we want to clone. We then take an egg cell from a female sheep and remove and discard the nucleus. We can then insert the nucleus from the sheep we want to clone into the empty egg cell, which is done using an electric shock to cause the nucleus and egg cell to fuse. The cell divides into a ball of cells which eventually becomes an embryo. This is implanted into the uterus of a surrogate mother, which will give birth to the cloned sheep.

What are the disadvantages of adult cell cloning?

Cloned animals often have developmental problems and shorter life spans. Cloning also reduces the gene pool which makes cloned organisms equally vulnerable to things like diseases. There are also religious and ethical implications since it involves humans manipulating and ‘creating’ life in an unnatural way.