A common first step in the making of a DNA library is to obtain DNA from many of your chosen organisms and cut this source DNA with a restriction enzyme. It is likely that some genes will contain sites for the chosen restriction enzyme, and in this case, your DNA library will not have a complete set of genes from your chosen source. There are several ways to avoid this problem, but one solution is to add smaller amounts of the restriction enzyme or decrease the time that the DNA is exposed to active enzyme. In the box below, explain why this approach may allow you to construct a more complete library.
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By adding smaller amounts of the restriction enzyme or decreasing the exposure time of the DNA to the active enzyme, you can potentially construct a more complete DNA library. This approach is aimed at reducing the chance of excessive digestion of the DNA by the restriction enzyme, which could result in the loss of certain genes from the chosen source.
Restriction enzymes are proteins that recognize specific DNA sequences and cleave the DNA at those sites. When creating a DNA library, the source DNA is cut into smaller fragments using a restriction enzyme. However, it is possible that some genes may contain the recognition sites for the chosen restriction enzyme, causing them to be cleaved during the digestion process. As a result, these genes may be lost from the DNA library.
To avoid this problem, the amount of the restriction enzyme added to the DNA can be reduced or the exposure time to the enzyme can be decreased. This approach lowers the chances of the enzyme cleaving the genes that contain its recognition sites and allows for a greater representation of genes in the library.
By adjusting the conditions of the restriction enzyme digestion, you can increase the likelihood of including a broader range of genes in the DNA library. This approach contributes to constructing a more complete library that better represents the genetic composition of the chosen organisms.