What are the differences between cDNA and genomic DNA library?

Question

Accepted Answer

Basis of differentiation

cDNA library

Genomic DNA library

Definition

Is a collection of only the genes that are encoded by an organism

Is a collection of the complete genomic DNA of an organism

Composition

Contains only genes expressed in a particular cell at a given period of time

Contains all of the cell’s genes, whether expressed or not

Coding vs noncoding sequences

Contains only coding sequences – does not contain introns

Contains entire sequences for introns and exons

Size

Smaller than genomic DNA library

Larger than cDNA library

Starting material

mRNA

DNA

Ingredients essential for construction

Reverse transcription enzyme

Ligases and restriction endonucleases

Involvement of reverse transcription

Reverse transcription is involved in the synthesis of the first cDNA strand

Reverse transcription is not involved

Number of recombinants to be screened

Fewer than genomic DNA library

Larger number than cDNA library

Vectors used

Plasmids, lambda phage, and phagemids are used for harboring smaller fragments as introns are absent

Lambda phage, cosmids, YAC, and plasmids are used to harbor larger fragments

Basis of differentiation	cDNA library	Genomic DNA library
Definition	Is a collection of only the genes that are encoded by an organism	Is a collection of the complete genomic DNA of an organism
Composition	Contains only genes expressed in a particular cell at a given period of time	Contains all of the cell’s genes, whether expressed or not
Coding vs noncoding sequences	Contains only coding sequences – does not contain introns	Contains entire sequences for introns and exons
Size	Smaller than genomic DNA library	Larger than cDNA library
Starting material	mRNA	DNA
Ingredients essential for construction	Reverse transcription enzyme	Ligases and restriction endonucleases
Involvement of reverse transcription	Reverse transcription is involved in the synthesis of the first cDNA strand	Reverse transcription is not involved
Number of recombinants to be screened	Fewer than genomic DNA library	Larger number than cDNA library
Vectors used	Plasmids, lambda phage, and phagemids are used for harboring smaller fragments as introns are absent	Lambda phage, cosmids, YAC, and plasmids are used to harbor larger fragments