Question

.In the process of creating a cDNA library, a large collection of double-stranded cDNAs are ligated into a cloning vector. The products of this ligation reaction are used to transform E. coli cells, and then these cells are plated on nutrient agar plates containing an antibiotic. Individual colonies can then be picked and analyzed. None of these cDNA clones are expected to be full length (including both the transcription initiation site and the polyA tail). Instead, the clones are shorter than the mRNAs from which they were derived. Why is this so?

Answer 1

In reverse transcription process, mRNA serves as a template in the synthesis of complementary DNA (cDNA). The cDNAs are shorter than mRNAs because the process that occur during reverse transcription degrade the mRNA or it may result in incomplete transcription.