A cDNA library is a collection of clones containing complementary DNA (cDNA) and is often intended to represent the genes that are expressed within a given cell or tissue type at a given period. The DNA is generated from a cell's mRNA by using reverse transcriptase and each piece is inserted into a bacterial plasmid.
In some cases it is easier to isolate mRNA molecule than the gene itself, because of selective expression of a particular gene, resulting in the relative abundance of that mRNA, for e.g., Insulin mRNA in the islet cells of Pancreas, ovalbumin mRNA in the hen oviduct on treatment with estrogens. In such cases, cDNA cloning is the approach of choice.
In some cases it is easier to isolate mRNA molecule than the gene itself, because of selective expression of a particular gene, resulting in the relative abundance of that mRNA, for e.g., Insulin mRNA in the islet cells of Pancreas, ovalbumin mRNA in the hen oviduct on treatment with estrogens. In such cases, cDNA cloning is the approach of choice.
