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A student prepares a reaction mixture for Polymerase Chain Reaction (PCR). The thermal cycler raises the temperature to 94^ C for the initial step but is mistakenly programmed to maintain this high temperature continuously. Which of the following steps of the PCR cycle will be the first to fail under these conditions?

Options

  1. ADenaturation
  2. BExtension
  3. CLigation
  4. DAnnealing

Correct answer

D. Annealing

Step-by-step solution

In a standard PCR cycle, the first step is denaturation, which requires a high temperature of 94^ C to separate the double-stranded DNA. The second step is annealing, which requires the temperature to be lowered to 50-60^ C to allow the oligonucleotide primers to hybridize to the single-stranded DNA templates. Because the temperature is continuously maintained at 94^ C , the primers will not be able to bind to the template DNA. Therefore, annealing is the first step that will fail to occur. Extension cannot occur w

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