Question

Which of the following best describes why PCR protocols contain numerous cycles of the denaturation/annealing/extension steps?

A. The denaturation step of each cycle only separates some of the source DNA. By performing numerous cycles, PCR generates copies of all the target sequences.

B. Each cycle of PCR allows Taq polymerase to partially synthesize the target sequence. Numerous cycles are necessary for the target sequence to be fully copied.

C. Each cycle of PCR incorporates some of the included primers into amplicons. Numerous cycles of PCR are required to ensure all primers are incorporated.

D. Each cycle of PCR doubles the amount of DNA synthesized, but the number of copies starts out small. Numerous cycles are required to produce a sufficient number of copies.

Answer 1

PCR protocols include numerous cycles to double the amount of the target DNA sequence in each cycle, using a three-step process involving denaturation, annealing, and extension, ultimately leading to a significant amplification of the DNA.

Step-by-step explanation:

The numerous cycles of denaturation, annealing, and extension in PCR protocols are essential to increase the quantity of the target DNA sequence. In each cycle of PCR, the amount of DNA is doubled through a process that involves the separation of DNA strands (denaturation), the binding of primers (annealing), and the synthesis of new DNA strands (extension) using Taq polymerase.

Denaturation is performed at a high temperature to separate the double-stranded DNA. During annealing, the temperature is lowered to allow primers to bind to the DNA template. In the extension step, the temperature is raised for the enzyme to synthesize new DNA strands. Thus, numerous cycles are crucial for producing a sufficient quantity of the target DNA sequence, where each cycle effectively doubles the number of DNA copies.