Cloning Genes

To study genes in the laboratory, it is necessary to have many copies on hand to use as samples for different experiments. Such experiments include Southern or Northern blots, in which genes labeled with radioactive or fluorescent chemicals are used as probes for detecting specific genes that may be present in complex mixtures of DNA.

Cloned genes also make it easier to study the proteins they encode. Because the genetic code of bacteria is identical to that of eukaryotes, a cloned animal or plant gene that has been introduced into a bacterium can often direct the bacterium to produce its protein product, which can then be purified and used for biochemical experimentation. Cloned genes can also be used for DNA sequencing, which is the determination of the precise order of all the base pairs in the gene. All of these applications require many copies of the DNA molecule that is being studied.

Gene cloning also enables scientists to manipulate and study genes in isolation from the organism they came from. This allows researchers to conduct many experiments that would be impossible without cloned genes. For research on humans, this is clearly a major advantage, as direct experimentation on humans has many technical, financial, and ethical limitations.