NEET Zoology Biotechnology Principles and Processes Questions Solved

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How is the amplification of a gene sample of interest carried out using polymerase

Chain Reaction (PCR)?

 Polymerase Chain Reaction (PCR): Each cycle has three steps:

(i) Denaturation; (ii) Primer annealing; and (iii) Extension of primers

PCR stands for Polymerase Chain Reaction. In this reaction multiple copies 

of the gene of interest are synthesised in vitro under three steps:

(i) Denaturation: In this double stranded DNA is converted to single stranded,

This is often achieved by heating or alkaline conditions. This is called melting of 

DNA.

(ii) Annealing: The two sets of primers (small chemical synthesized oligonucleotides

that are complementary to the regions of DNA) undergo biochemical process of 

annealing at an optimum temperature of .

(iii) Extension: The enzyme DNA polymerase extends the primers using the nucleotide 

provided in the reaction and the genomic DNA as template. If the process of replication

of DNA is repeated many times, the segment of DNA can be amplified to approximately

billion times. Such repeated amplification is achieved by the use of a thermostable DNA

polymerase and the amplified fragment if desired can be used to ligate with a vector

for further cloning.

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