DNA from genome or mRNA from tissue
Description and Procedure:
cDNA Library or complimentary DNA library represents all active genes in a particular tissue. mRNAs from the active tissue are extracted; reverse transcriptase converts mRNAs into a strands of DNA (without introns); DNA polymerase is used to add the complimentary strand (coding for mRNA) to the single strand making it double stranded.
Uses or Function:
Collection of 100s of clones of DNA fragments or genes from an organism which can be used to locate or map genes which are active in the tissue under investigation rather than all possible genes found in the organism.