Genomic libraries

-Cloning DNA,population of recombinant DNA molecules, often in plasmid or phage vectors, maintained

either in bacterial cells or as phage particles.

- termed a clone bank or library.

-The term genomic library is often used to describe a set of clones representing the entire genome of an organism, and the production of such a library is usually the first step in isolating a DNA sequence from an

organism’s genome.

 the steps for creating a genomic library from a large genome :

1. Extract and purify DNA.
2. Break the DNA with a restriction enzyme, This creates fragments that are similar in size, each containing one or more genes.
3. Insert the fragments of DNA into vectors that were cut with the same restriction enzyme. Use the enzyme DNA ligase to seal the DNA fragments into the vector. This creates a large pool of recombinant molecules.
4. These recombinant molecules are taken up by a host bacteria by transformation, creating a DNA library

 

Characteristics of a good genomic library In theory,

1- should represent the entire genome of an organism as a set of overlapping cloned fragments, which will therefore

               

 2-enable the isolation of any sequence in the genome.

3-The fragments for cloning should ideally be generated by a sequence-independent procedure, ensuring that the fragments are generated at random

               

4-cloned fragments should be maintained in a stable form with no misrepresentation of sequences due to recombination or differential replication of the cloned DNAs during propagation of the recombinants.

Categories: genes