Construction of a cDNA Library
Populations of mRNA accumulated in a given tissue are representative of that tissue. It is thus very important to be able to characterize the genes expressed in a given organ. However, the manipulation of mRNAs is a delicate process (small quantity, sensitivity to nucleases) and they must be transformed into double-stranded DNA that can be easily manipulated and adapted to cloning in bacterial vectors. A library of cDNA (complementary DNA) is thus representative of populations of mRNA present in a given tissue at a particular stage of its development. Unlike a genomic library, a cDNA library is specific to a tissue. It can be considered a " snapshot" of populations of mRNA represented in an organ.