DNA LIBRARIES

Dr. E

What Are DNA Libraries?

• A DNA library is a collection of DNA fragments that have been cloned into a plasmid and the plasmid is transformed into a bacteria for propagation and storage.

• Ideally contains at least one copy of every sequence.

• Allows researchers to identify and isolate the DNA fragments that interest them for further study.

What Are The Two Types Of Libraries?

• Genomic library-A set of cloned DNA fragments that collectively represent the entire genome of a given organism.

• cDNA library-represents a sample of all the expressed mRNA’s from a particular cell type, particular tissue, or an entire organism which has been converted back to DNA. Thus represents the genes that were actively being transcribed (turned on).

Applications Of cDNA Libraries

• Discovery of novel genes

• Determine what mRNA’s are expressed in different cells or tissues

• Determine what mRNA’s are expressed at different developmental stages

• Study alternative splicing

Applications Of Genomic Libraries

• Determine the complete genome sequence

• Study of regulatory sequences

• Study promoters

• Study intergenic regions

• Study Introns

• Study non-expressed gened

Making a Genomic Library

Making a cDNA Library

Separating mRNA

Creating cDNA

Inserting cDNA Fragment into

Plasmid

Where is cDNA Fragment Inserted

into Plasmid?

pTriplEx Plasmid

Anatomy Of A Gene