Sections of DNA can be amplified using the polymerase chain reaction (PCR) - Scottish Highers Biology - Question 1 - 2022
Question 1
Sections of DNA can be amplified using the polymerase chain reaction (PCR). The steps in one cycle of PCR are shown.
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5' _____________________ 3'
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Worked Solution & Example Answer:Sections of DNA can be amplified using the polymerase chain reaction (PCR) - Scottish Highers Biology - Question 1 - 2022
Step 1
Give a temperature for step 1 to occur.
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Answer
A suitable temperature for step 1 of PCR typically ranges between 92°C to 98°C to facilitate the denaturation of DNA.
Step 2
Describe one role of the primers in PCR.
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Primers serve as starting points for DNA polymerase to initiate the replication process. They bind to specific sequences on the template DNA and provide the necessary free 3' hydroxyl group for nucleotide addition.
Step 3
Name another enzyme necessary for DNA replication in cells.
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DNA ligase
Step 4
Suggest why this enzyme is not required for step 3 in PCR.
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DNA ligase is not needed in PCR because, during the amplification process, the DNA strands are replicated continuously without the need to join fragments together, as the PCR process involves the synthesis of entire DNA strands.
Step 5
Explain why DNA polymerase extracted from human cells would not replicate DNA in PCR.
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DNA polymerase from human cells would be denatured due to the high temperatures used in PCR, which are not conducive to its activity. Additionally, this enzyme may not be heat-resistant.
Step 6
State one practical application of PCR.
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One practical application of PCR is in solving crimes or forensic investigations, as it allows for the amplification of DNA from small samples, aiding in identification.
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