Question

What is DNA libraries, write their types, advantages and disadvantages?

Answer 1

DNA library or the gene library is the collection of DNA sequences from different organisms. These DNA sequences have been extracted, purified, sequenced and associated with a vector so as to use them for the purpose of analysis, comparative detection etc.

Depending on the source of DNA, the DNA library can be of the following two types:

A) Genomic Library: In these libraries, the whole genome of an organism is used. The information of the whole genome is made available. These can be further of two types:

1. Nuclear Genomic Library: Nuclear DNA is purified and stored.

2. Organelle Genomic Library: Organellar DNA (from mitochondria or chloroplast) Is purified and stored

B) cDNA Library: When the mRNAs from a cell are extracted and DNA is made from mRNA through reverse transcription, such a DNA is called cDNA (complementary DNA). In cDNA library, only the cDNA (that are functional in a cell) are made and stored. In other words, cDNA library has a collection of mRNAs of an organism, in the form of cDNA.

Advantages of DNA libraries:

1. Ease of studying the genome of different organisms
2. Identification of genes in an organism.
3. Creation of transgenic organisms.
4. Gene therapy.
5. Pharmaceutical applications through the study of genetic defects.

Disadvantages of DNA libraries:

1. Extraction and sequencing of larger genome is a difficult task.
2. cDNA libraries give a picture of exons only, the alternative splicing os not considered.
3. Contamination of DNA