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A researcher plots a temperature versus time graph for one complete cycle of a Polymerase Chain Reaction (PCR). The resulting curve displays three distinct temperature plateaus in sequence: Phase A at 94^ C , Phase B at 54^ C , and Phase C at 72^ C . Which of the following primary molecular events occurs during Phase B?

Options

  1. ABreaking of hydrogen bonds between the two strands of template DNA
  2. BPolymerization of deoxynucleotides by Taq polymerase
  3. CHybridization of oligonucleotide primers to the single-stranded template DNA
  4. DFormation of phosphodiester bonds by DNA ligase to join DNA fragments

Correct answer

C. Hybridization of oligonucleotide primers to the single-stranded template DNA

Step-by-step solution

The Polymerase Chain Reaction (PCR) consists of three main steps in each cycle, characterized by specific temperature requirements: 1. Denaturation (Phase A at 94^ C ): The double-stranded template DNA is heated to break the hydrogen bonds, resulting in single-stranded DNA. 2. Annealing (Phase B at 54^ C ): The temperature is lowered to allow two sets of oligonucleotide primers to hybridize (bind) to their complementary sequences on the single-stranded template DNA. 3. Extension (Phase C at 72^ C ): The temperature

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