What are the differences between cDNA and genomic DNA library?

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