PCR

Question 1

What is PCR used for?

Answer 1

To amplify a single sequence of DNA into many more identical copies in vitro.

Question 2

What does the method rely on?

Answer 2

Thermal cycling - repeated heating and cooling in a human cycler

Question 3

What does PCR require?

Answer 3

• Primers (pieces of sigle stranded DNA complementary to a specific sequence at the 3’ end of the DNA strand to be replicated)
• heat tolerant DNA polymerase
• a supply of the 4 types of nucleotide

Question 4

Outline of process

Answer 4

1) DNA strand are separated
2) Primers are added and bond to DNA
3) DNA polymerase replicates the DNA

Question 5

What is the first step in PCR?

Answer 5

DNA is heated (95c) to break the hydrogen bonds between base pairs and separate the two strands

Question 6

What is the 2nd stage of PCR?

Answer 6

DNA is cooled (50-65) to allow each primer to anneal to its target sequence

Question 7

What is the 3rd stage of PCR?

Answer 7

DNA heated again (70-80) and heat tolerant DNA polymerase adds nucleotides to the primers at the 3’end of the original DNA strand

Question 8

How many molecules does DNA produce in the 1st, 2nd, 3rd cycles of DNA replication?

Answer 8

1st cycle produces 2 identical molecule of DNA
2nd cycle produces 4 identical molecules of DNA
3rd cycle produces 8 identical molecules of DNA

Question 9

State a therapeutic use of PCR

Answer 9

Paternity testing

Question 10

State a use of PCR

Answer 10

Human genome project
DNA fingerprinting
Paternity testing