Polymerase Chain Reaction (PCR)

Question 1

What is needed for PCR?

Answer 1

DNA fragment to be copied
Free dna nucleotides
DNA polymerase (joins DNA nucleotides (phosphodiester bonds). Taken from bacteria in hot springs that can withstands a high temperature.
DNA primers (short, single-stranded DNA sequences complementary to the DNA at both ends of the target STR).
Thermonuclear (a computer controlled machine which controls the temperature during the reaction).

Question 2

Denature

Answer 2

1. Heat up dna to 95°c
2. Hydrogen bonds denature and break

Question 3

Annealing

Answer 3

1. Temperature is cooled to 55°c so the two primers can bind to dna (through complementary base pairing)
2. DNA primers signal to the DNA polymerase where to bind.

Question 4

Extension

Answer 4

1. DNA polymerase attaches to the DNA and primers (where dna is double stranded) and moves along the single dna strands.
2. Free DNA nucleotides complementary base pair and DNA polymerase forms phosphodiester bonds between the DNA nucleotides.
3. Temperature is heated to 72°c (optimum temperature for DNA polymerase from bacteria in hot springs to work).