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The Steps of PCR quiz

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  • What are the three main steps of each PCR cycle?
    The three main steps are denaturation, annealing, and extension.
  • At what temperature does the denaturation step of PCR occur?
    Denaturation occurs at about 95 degrees Celsius.
  • What happens to DNA during the denaturation step of PCR?
    The double-stranded DNA is separated into single strands by breaking hydrogen bonds.
  • Why is Taq polymerase used in PCR?
    Taq polymerase is thermostable and does not denature at the high temperatures used in PCR.
  • What is the purpose of the annealing step in PCR?
    Annealing allows DNA primers to bind to the single-stranded DNA through complementary base pairing.
  • At what temperature does the annealing step of PCR occur?
    Annealing occurs at about 55 degrees Celsius.
  • Is Taq polymerase active during the annealing step of PCR?
    No, Taq polymerase remains inactive at the cooler temperature of the annealing step.
  • What happens during the extension step of PCR?
    Taq polymerase extends the DNA primers by adding nucleotides to synthesize new DNA strands.
  • At what temperature does the extension step of PCR occur?
    Extension occurs at about 72 degrees Celsius, which is optimal for Taq polymerase activity.
  • What direction does Taq polymerase extend the DNA primers during PCR?
    Taq polymerase extends the primers in the 5' to 3' direction.
  • What is the result of one cycle of PCR?
    One cycle produces two identical copies of the original DNA template.
  • How does PCR achieve exponential amplification of DNA?
    Each cycle uses the products of the previous cycle as templates, doubling the DNA amount each time.
  • What components must be present in the PCR reaction mixture?
    The mixture must contain template DNA, DNA primers, Taq polymerase, and DNA nucleotides.
  • What is the role of DNA primers in PCR?
    DNA primers bind to the single-stranded DNA and provide a starting point for Taq polymerase to extend.
  • Why is it important that Taq polymerase is thermostable in PCR?
    It must withstand the high temperatures of denaturation and remain functional for DNA synthesis.