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Difference between Genomic and cDNA Library

A set of techniques adopted for gene cloning for a particular purpose is said to be a gene cloning strategy. There are several gene cloning strategies in recombinant technology. DNA fragments are generated by cutting the DNA with a specific restriction endonuclease. These fragments are ligated into a vector molecules  and the collection of recombinant molecules is transferred into host cells, one molecule in each cell. The total number of all DNA molecules makes up the library. Two main types of libraries can be used to isolate specific DNAs: genomic and cDNA libraries.
Genomic library
A genomic library contains DNA fragments that represent the entire genome of an organism, whereas in case of cDNA library mRNA from an organism or from an organism or from specific cells of an organism are extracted and then complementary DNA (cDNAs) are prepared from the mRNA in a multistep reaction catalysed by the enzyme reverse transcriptase. The resulting double stranded DNA fragments are then inserted into a suitable vector and cloned, creating a population of clones called cDNA library. Since, a cDNA library is derived from mRNA, the library contains the coding region of expressed genes only, with no introns or regulatory regions. Such a library lacks the non coding DNA that makes up a large portion of many eukaryotic genomes.
cDNA library
Genomic Library vs cDNA libraries
Genomic Library
cDNA libraries
It include all possible fragments of DNA from a given cell or organism. cDNA library carries only expressed gene sequences.
It is larger It is smaller
It represents the entire genome of an organism having both coding and non coding regions. It represents only the expressed part of the genome and contain only coding sequences called ESTs
Expression of genes taken from genomic library is difficult in prokaryotic system like bacteria due to absence of splicing mechanism. cDNA has only coding sequences therefore can be directly expressed in prokaryotic system.
 Vectors used genomic library include plasmid, cosmid, lambda phage, BAC and YAC in order to accommodate large fragments Vectors used cDNA library include plasmid, phagemids, lambda phage etc to accommodate small fragments as cDNA has no introns.
Uses of Genomic Library Uses of cDNA Library


  1. great job. thanks its very helpful for me

  2. Nice side by side comparison. I'd love to read more on the different uses of both library types.


  4. The process of cDNA cloning creates many fragments of double stranded DNA. By the nature of reverse transcriptase, the cloning process frequently aborts, creating DNA fragments representing only part of the gene. This makes it difficult to obtain a highly representative large-copy-number cDNA library. From the construction of cDNA library it is possible to identify particular cDNA clones. This is useful in DNA sequencing, giving a researcher the ability to predict an amino acid sequence and the eventual protein. The genomic sequence can be identified, allowing specific gene control regions to be located. Hybridization assays can be performed, allowing the identification of transcriptional changes between normal and mutated regions of DNA sequences. Get to know more from centers like CD Genomics, who are experts in dna & genome sequencing service, genotyping, health diagnostics, bioinformatics, custom cdna library development. Thanks.

  5. really helpful

  6. great job its very helpful for me

  7. thank u . it is very much help me to understand the concept of both the cdna and genomic library.

  8. Didn't answer any of my questions

  9. this is very helpful, thanks a lot!

  10. precisely explained. thank you :)

  11. Wow! Awesome information its really helpful

  12. no improvements needed...the website is already awesome and very helpful..just keep the work up.


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