THE FARM REVEALED
PROGRAMME 3: CLONING
BACKGROUND
Cloning means producing offspring without having sex, with the consequence that the offspring are genetic copies of the parent. Clones can be made of plants, animals, cells, or stretches of DNA. The key thing is that they are genetically identical to one another.
Being genetically identical means having the same DNA or Deoxyribonucleic acid. You can think of DNA as similar to a molecular chain, in which there are four different types of links. The order, or sequence, of the links is unique to each individual person. A genetic copy or a clone has the exact same DNA sequence as its parent.
The new technology of cloning literally means copying DNA from one bacterium, plant or animal to another, sometimes across different species. Animal cloning is more complicated than plant cloning. Plants are able to regenerate from a tiny section of tissue – but animals are not. Traditional agricultural and gardening techniques have relied upon cloning for centuries. Most of the fruit and vegetables we eat today are clones.
There are problems associated with cloning. Where a crop species is genetically uniform, a pathogenic fungus or bacterium can attack the whole lot very easily and quickly. A genetically diverse crop, however, is much more resistant to attack because a disease organism will be able to attack some, but not all, genetic variants of the crop.
It is important for the continuance of any species, wild or domestic, to maintain genetic diversity. Endangered animal and plant species often suffer from something called inbreeding. This is where there is such a small population of individuals left breeding that their genes become increasingly similar. In other words, they lose genetic diversity. Like the crop plants, this means that they can become vulnerable to disease. They also become much more vulnerable to genetic diseases.
Many of us carry disease genes, but as we all have two copies of each gene, one faulty one doesn't really matter. Inbreeding leads to a situation in which individuals are more likely to inherit two copies of the same disease gene, with the result that they get the disease (for example, cystic fibrosis). This happens within small populations of endangered animals and is why maintaining genetic diversity is so important to conservation biologists.
