Question

The first step of PCR is called annealing?
1) True
2) False

Answer 1

The first step of PCR is not called annealing; it is false. The first step of PCR is denaturing, which separates the DNA strands, followed by annealing where primers bind to the single-stranded DNA, and extension where new DNA is synthesized.

Step-by-step explanation:

The statement that the first step of PCR is called annealing is false. The Polymerase Chain Reaction (PCR) is a technique used in molecular biology to amplify a segment of DNA, producing a large quantity of a specific DNA sequence. The process of PCR involves three main steps:

1. Denaturing: This step involves heating the DNA to around 95ºC to separate the double-stranded DNA into two single strands.
2. Annealing: In this step, the temperature is lowered to approximately 55ºC to allow the primers to bind, or anneal, to their complementary sequences on the single-stranded DNA.
3. Extension: Finally, the temperature is raised to about 72ºC to enable the DNA polymerase to synthesize the new DNA strand by adding nucleotides.

The cycle of denaturing, annealing, and extension is repeated multiple times to exponentially increase the amount of targeted DNA sequence. PCR is crucial in various applications such as cloning, gene expression analysis, and genetic testing.