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Multiple Choice
What is the correct sequence of events that occur in a polymerase chain reaction (PCR)?
A
Denaturation, Extension, Annealing
B
Extension, Denaturation, Annealing
C
Denaturation, Annealing, Extension
D
Annealing, Denaturation, Extension
Verified step by step guidance
1
Understand the purpose of PCR: PCR is a technique used to amplify a specific segment of DNA, making millions of copies of a particular DNA sequence.
Identify the first step: Denaturation. In this step, the double-stranded DNA is heated to around 94-98°C to break the hydrogen bonds between the strands, resulting in two single strands of DNA.
Identify the second step: Annealing. The temperature is lowered to around 50-65°C to allow primers to bind or anneal to the complementary sequences on the single-stranded DNA templates.
Identify the third step: Extension. The temperature is raised to around 72°C, which is the optimal temperature for Taq polymerase to synthesize a new DNA strand by adding nucleotides to the annealed primer.
Recognize the cycle repetition: These steps are repeated for 25-35 cycles to exponentially amplify the target DNA sequence, resulting in millions of copies.