Chapter 8, Problem 6CT

Summary Introduction

To answer:

The number of DNA molecules synthesized in PCR reaction using 15 DNA helices in 15 cycles.

Introduction:

PCR technique is a rapid method used to amplify the huge amount of a specific segment of the DNA molecule. It is used to generate a billion copies of identical molecules of the DNA segment within few hours. It is used to analyze genomic variation and mainly involved in clinical studies. The important components used for PCR reactions are DNA, primer, deoxyribonucleotide triphosphates (A, T, G, and C) or dNTPs, Taq DNA polymerase, MgCl2, and buffer. There are nearly 30 cycles are involved in PCR to produce numerous copies of exact replicas.

The main steps of PCR in each cycle:

Denaturation: Separation of double-stranded DNA into two single-strand DNA molecules by cleaving the hydrogen bonds at 94°C.

Annealing: Binding of primers (20 - 30 nucleotides long) to ends of ssDNA molecules at 65°C.

Extension: Addition of dNTPs at 3’ site of the primer by DNA polymerase to synthesize complementary stand of ssDNA at 72°C.