Basic concepts about cDNA, gene and genomic library
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Library:- It is a convenient storage mechanism of genetic information. 1. cDNA library 2. Genomic library 1. cDNA library:- It is a collection of cloned DNA sequences that are complementary to the mRNA that was extracted from an organism or tissue. > cDNA is developed by the process of reverse transcription. > Reverse transcription:- Genetic information contained in mRNA is converted back into a double stranded DNA form. The enzyme responsible for this is called reverse transcriptase. > Reverse transcriptases:- They are isolated from Retroviruses. Eg.- Moloney murine leukemia virus (MMLV). They have polymerase activity, but do not have exonuclease activity. > Primer:- MMLV will use mRNA as a template, but requires a primer. Eukaryotic mRNA has a 3' poly A tail. Therefore we can use poly dT as a prime. > RNAse H:- This enzyme has endonuclease activity, so create nicks in the RNA. > DNA polymese - I:- RNA fragments now serve as primers for DN...