polymerase chain reaction - lqc 2b

Question 1

what is PCR used for?

Answer 1

the amplification/ making multiple copies of dna

Question 2

role of dna in a pcr reaction tube

Answer 2

the sample needing to be amplified

Question 3

role of dna primers in PCR reaction tube

Answer 3

anneal to the dna either side of the section of dna needing to be amplified

Question 4

role of dna nucleotides in a PCR reaction tube

Answer 4

enable new dna strands to be constructed

Question 5

role of taq polymerase in a PCR reaction tube

Answer 5

joins dna nucleotides together by phosphodiester bonds in condensation reactions to form the new dna strands

Question 6

role of Mg^2+ in a PCR reaction tube

Answer 6

cofactor for taq polymerase

Question 7

role of buffer in a PCR reaction tube

Answer 7

maintain the correct pH for taq polymerase

Question 8

what happens at 95°c in the PCR cycle

Answer 8

denatures the double stranded dna molecule so that the two strands separate go make single stranded dna

Question 9

what happens at 55°c in the PCR cycle

Answer 9

Primers anneal either side of the section of DNA that needs to be amplified. Allows Taq polymerase to bind in the correct place and start DNA replication

Question 10

what happens at 70°c in the PCR cycle

Answer 10

Taq polymerase binds to the primer region. Condensation reactions take place to create a new DNA strand – Elongation phase

Question 11

how many times must the PCR cycle be repeated

Answer 11

25-30 (sometimes up to 40)