pcr cram

Question 1

Explain

What does PCR happen in?

Answer 1

Thermal Cycler.

Question 2

Recall

Acronym for the steps in PCR

Answer 2

DAE

Question 3

List

Three steps in PCR.

Answer 3

• Denaturation
• Annealing
• Extension
  (+ repeat as needed, PCR is cyclic, and exponential.)

Question 4

List

Requirements for PCR.

Answer 4

• taq DNA polymerase enzyme (synthesizes new DNA strands, 5’ to 3’)
• buffer solution (to keep pH steady)
• DNA primers (for one end of each DNA strand)
• an assortment of nucleotides (to be synthesized by polymerase)

Question 5

Explain

Why taq DNA polymerase is used, as opposed to normal DNA polymerase?

Answer 5

taq DNA polymerase has higher heat resistance.
normal dna polymerase would denature if put through a thermal cycler.

Question 6

Explain

Denaturation

Answer 6

DNA is heated to ~95°C, breaking the H-bonds between bases, and splitting (denaturing) the DNA.

Question 7

Explain

Annealing

Answer 7

Temperature is lowered to ~50°C, and primers are appended to the 3’ side of both denatured strands of DNA.

Question 8

Explain

Extension

Answer 8

Temperature is re-raised to 72°C, taq polymerase’s optimum temperature, and the DNA is then synthesized like normal DNA replication.

Question 9

bonus

chiasma(ta)

Answer 9

where two homologous chromosomes overlap in chrossing over