Question

What is a cDNA library, and for what purpose can it be used?

Short answer

Answer: A cDNA library is a collection of complementary DNA (cDNA) molecules derived from the messenger RNA (mRNA) molecules found in a specific tissue or organism. This library preserves the original gene expression pattern of the source material and can be used for various molecular biology and genomic research purposes. Applications of a cDNA library include gene expression studies, cloning genes, functional genomics, and sequencing.

Step-by-step solution

Introduction

A cDNA library is a collection of complementary DNA (cDNA) molecules derived from the messenger RNA (mRNA) molecules found in a specific tissue or organism. This library preserves the original gene expression pattern of the source material and can be used for various molecular biology and genomic research purposes.

cDNA synthesis

The first step in creating a cDNA library is synthesizing cDNA from the mRNA molecules. This process is called reverse transcription. An enzyme called reverse transcriptase specifically binds to the mRNA template, recognizes the poly-T tail, and synthesizes a single-stranded cDNA molecule. This single-stranded cDNA is further converted into a double-stranded cDNA using DNA polymerase.

cDNA Cloning

Once double-stranded cDNA is synthesized, it's cloned into a suitable vector (such as a plasmid) using restriction enzymes and DNA ligase. The vector containing the cDNA is then introduced into a host organism, typically a bacterial cell, which helps amplify and replicate the cDNA.

Library Screening

After cloning, the cDNA library can be screened for the desired cDNA. Various methods, such as nucleic acid hybridization and polymerase chain reaction (PCR), are used to identify the cDNA of interest from the library.

Applications of cDNA library

The cDNA library is used for numerous purposes: 1. Gene expression studies: By comparing cDNA libraries of different tissues or organisms, researchers can determine the patterns of gene expression. 2. Cloning genes: A cDNA library can serve as a source of specific genes for cloning and further analysis. 3. Functional genomics: cDNA libraries provide crucial information on gene function and regulation in the source tissue or organism. 4. Sequencing: cDNA sequences can be determined and compared to genomic sequences to identify exons and introns within the genes.