In: Biology
CR is a molecular biology technique that allows us to replicate DNA in an in vitro system without the need for a ‘replisome’. What conditions or elements used in PCR mimic the effects of the following parts in the replisome? Explain your answer in 1 or 2 sentences.
a) Helicase (2 marks)
b) Primase (2 marks)
c) DNA pol III (2 marks)
PCR is used to amplify target gene sequences. It is an invaluable technique used in molecular biology and genetics.
PCR reaction components:
Taq polymerase
Buffer
iii. dNTPs
iv. Primers
v. Template
PCR steps:
i. Denaturation (92'C to 94'C): Unwinding of the DNA duplex
ii. Annealing (50'C to 65'C): Binding of the primer to the template DNA
iii. Extension (70'C to 72'C): Extension of the primer by Taq polymerase
iv. Repeat
Primer is a short oligonucleotide sequence (15 to 30 ntd) that binds specifically to the template DNA using sequence complementarity. The primer binds to the template DNA only when the temperature is below the Tm of the DNA-primer duplex.
Answers:
a. Helicase: High temperature used during the denaturation step unwinds the DNA duplex.
b. Primase: We use synthetic oligonucleotides as primers in PCR.
c. DNA polIII: We use Taq polymerase in PCR.
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