Question

What is a DNA library?

Answer 1

DNA library is a group of DNA fragments that together constitute an entire genome of an organism. It is of two types: genomic library and cDNA (complementary DNA) library. Genomic library contains DNA which represents the entire genome while the cDNA library used to clone eukaryotic genes in prokaryotes.

Complete answer:
The term library is known as collection of books. In molecular biology the term library refers to the collection of DNA fragments. To create a library, we need to take the DNA from desired organisms then step by step follow the process. First of all we cleave the DNA with the help of restriction enzymes then combine them with vectors. After that insert these recombinant vectors into bacteria where the amplification starts. The vectors start replicating in the bacteria. And these fragments make up our DNA library.

DNA library are of two types:
- Genomic library
- cDNA library

Genomic library: It is a collection of DNA clones. To make a genomic library, isolate the DNA fragments with the help of restriction endonuclease enzymes and insert the fragment into appropriate vectors.

cDNA library: It is a collection of DNA clones synthesis from mRNA. cDNA libraries are specific libraries which contain only protein encoding genes. To make cDNA library first of all isolate mRNA from eukaryotic cells to form cDNA in the presence of reverse transcriptase. cDNA is single stranded DNA. To make it double strand add DNA polymerase enzyme into it which catalyses the second DNA strand and then replace RNA primers with DNA strand. Double stranded DNA then injected into the cloning vector undergo amplification and form sequence.

Note: DNA library is a stored collection of DNA fragments that have been cloned into vectors. The purpose of a DNA library is to help researchers to find out and isolate the DNA fragments that interest them for study.