Q.What is DNA library ?

Gene Library (Genomic and cDNA Libraries)

An organism's genome is enormous — far too big to study all at once. So biologists do what a real library does with a huge collection of information: they break it into manageable pieces and store each piece so it can be found again. A gene library is exactly this — a complete collection of cloned DNA fragments that together represent an organism's genetic material.

Why build a library

If you want to study or isolate a single gene, you first need it as a clonable piece of DNA that you can grow in large amounts. Rather than hunting one gene at a time, scientists chop the whole genome into fragments, insert each into a vector, and store the lot inside host cells. Any gene you later need is already "on a shelf" in the collection.

The two types

How each is built

• Genomic library: cut the whole genome with restriction enzymes → insert fragments into vectors (plasmids, phages, BACs) → introduce into host bacteria. Each colony carries a different fragment. …