Win up to 100% scholarship on Aakash BYJU'S JEE/NEET courses with ABNAT Win up to 100% scholarship on Aakash BYJU'S JEE/NEET courses with ABNAT

cDNA vs. Genomic DNA library

The DNA library is a collection of DNA fragments that have been cloned into vectors to recognize and isolate desired DNA fragments. There are two types of libraries – cDNA and genomic libraries.

Download the Complete Guide to NEET UG Prep
Download Now

The genomic DNA libraries comprise large DNA fragments. On the other hand, cDNA libraries are constituted by cloned, reverse-transcribed mRNA. As a result, they are devoid of the DNA sequences relative to the genomic areas which are not expressed such as the introns.

Also see: NEET 2022 Answer Key With Solutions

cDNA Library (Complementary DNA library)

  • cDNA – It is a DNA copy of an mRNA molecule generated by reverse transcriptase, a DNA polymerase that can use either RNA or DNA as their template
  • These are prepared using mRNA as templates, their starting material
  • They are representative of only those genes of the genome that are expressed given specific conditions
  • cDNA does not have introns, and hence can be expressed in prokaryotic cells

Genomic DNA library

  • Genomic DNA is the chromosomal DNA of an entity representative of the collection of its genomic content. They are different from that of complementary DNA, mitochondrial DNA or bacterial plasmid DNA. These are directly prepared from the genomic DNA, and represent the complete genome of an entity
  • For their construction, ligases and restriction endonucleases are vital
  • As it carries introns, they are incapable of expression in the prokaryotes. Moreover, prokaryotes lack the machinery for processing introns

Key Difference between cDNA and Genomic DNA library

The table below depicts the differences between cDNA and Genomic DNA library.

cDNA library
Genomic DNA library
What it is
Collection of clones having complementary DNA to the mRNA of an entity Collection of clones having the complete genomic DNA of an entity
What does it contain?
Represents genes expressed in a particular cell at a given period of time Represents all genes
Smaller compared to genomic DNA library Vast in comparison to cDNA library
Coding and non-coding sequences
Clone contains sequences seen on mRNA only, not the complete gene. Contains sequences for introns and exons. Genomic clones can have sequences of the complete gene
Important substance required for their construction
Reverse transcriptase enzyme Ligases and restriction endonucleases
How many recombinants to be screened?
The number is way lesser in comparison to the genomic DNA library Way greater number of recombinants compared to cDNA library
Material required to start
Expression in prokaryotic system
Can be directly expressed as it has only coding sequences Gene expression extracted from the genomic library is challenging in the prokaryotic systems, as they are devoid of a splicing mechanism
Role in reverse transcriptase
Occurs in the synthesis of the first cDNA strand Not involved
Vectors used
Phagemids, Plasmids, Lambda phage for harbouring smaller fragments due to the absence of introns Cosmids, plasmids, Lambda phage, YAC, BAC to harbour larger fragments

You read some differences between cDNA and Genomic DNA library. For more such articles, visit us at BYJU’S NEET.

More here:

Difference Between Rods and Cones
Difference between “mRNA”, “tRNA” and “rRNA”
Difference between “Denaturation” and “Renaturation”
Difference between Heredity and Inheritance
Difference between cleavage and mitosis


Leave a Comment

Your Mobile number and Email id will not be published.