Choose the option that is showing the correct sequence of events occurring in each cycle of polymerase chain reaction (PCR).

Options

A. Denaturation extension primer annealing.
B. Primer annealing denaturation extension.
C. Denaturation primer annealing extension.
D. Extension primer annealing denaturation.

Answer

To solve the question regarding the correct sequence of events occurring in each cycle of polymerase chain reaction (PCR), we can break down the process into its three main steps:

1. **Denaturation**:
- The first step in the PCR cycle is denaturation. During this step, the double-stranded DNA template is heated to around 92 degrees Celsius. This high temperature causes the hydrogen bonds between the two strands to break, resulting in the separation of the DNA strands into two single strands.

2. **Primer Annealing**:
- After denaturation, the temperature is lowered to allow the primers to anneal (bind) to the single-stranded DNA. This step is crucial because the primers provide a starting point for DNA synthesis. The primers attach to the 3' ends of the single strands of DNA.

3. **Extension**:
- The final step is extension, where the temperature is raised again to the optimal temperature for DNA polymerase to function (usually around 72 degrees Celsius). During this step, DNA polymerase adds nucleotides to the 3' end of the primers, synthesizing new strands of DNA complementary to the template strands.

Putting these steps together, the correct sequence of events in each cycle of PCR is:
- **Denaturation**
- **Primer Annealing**
- **Extension**

Thus, the correct answer to the question is: **Denaturation, Primer Annealing, Extension**.