Polymerase chain reaction

what is pcr

the process to create vast quantities of DNA identical to trace / original samples

DNA amplification

what does PCR require (5)

purified DNA fragments to be amplified

nucleotides used to generate new strands

type of DNA polymerase - Taq polymerase

DNA primers complementary to section to be amplified

PCR machine

what are the 3 stages of PCR

denaturing

annealing

extension

what temp is denaturing

95

what happens in denaturing

the DNA strand is heated up so that the hydrogen bonds holding the two strands together break, separating (dissociating) the double stranded DNA into single stranded DNA

what temp is annealing

55

what happens in annealing

cooled to allow primers to bind to their specific binding regions of the single stranded DNA (taq polymerase is added here)

what side of DNA does the primer bind to

3'

two types of primers

forward primer - binds to template strand where the start codon is located

reverse primer - binds to coding strand where the stop codon is located

what temp is extension

72

what happens in extension

taq polymerase is at its optimal functioning temperature and it binds to the primers on each side and begins to generate a complementary stranded DNA

properties of taq polymerase

thermostable, heat resistant

what degree does PCR multiply DNA

exponentially

2^x

what is a primer

A short segment of DNA that acts as the starting point for a new strand (18-24 bases long)

specifically designed by scientists

uses of PCR (5)

DNA sequencing

DNA profiling - family tests / finger prints

gene cloning

transformation

making artificial genes

why is taq polymerase used

because it is thermostable ie it can withstand the high heats during denaturing as the process is repeating without denaturing

what is the term for the products of PCR

semiconservative - one strand is new and one is retained from the previous cycle