CDNA library
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- The title of this article is incorrect because of technical limitations. The correct title is cDNA library.
In molecular biology, a cDNA library refers to a complete, or nearly complete, set of all the mRNAs contained within a cell or organism. Because working with mRNA is difficult, researchers use an enzyme called Reverse Transcriptase which will produce a DNA copy of each mRNA strand. Referred to as cDNA these reverse transcribed mRNAs are collectively known as the library.
Such a library has several uses. A cDNA of an eukaryotic organism (for example, a human) can be cloned into a prokaryotic organism (for example, E. coli) and expressed (translated into the appropriate protein) there (with limitations, for example posttranslational modification). A cDNA library is also important for analysis through bioinformatics. The complete cDNA library of an organism gives the total of the proteins it can possibly express. Also, the cDNA sequence gives the genetic relationship between organisms through the similarity of their cDNA.
cDNA Library Construction
A cDNA library may originate from many sources. For example a researcher may be interested in what mRNAs are present in the embryo of an organism, thus they would produce a cDNA library from only embryo tissue. This cDNA library could then be used as a probe for DNA microarrays or as a clonal inserts into bacteria chromosomes. Often researchers will compare the mRNA profile from different tissues or developmental stages to determine genetic differences.