The diagram represents three steps during one cycle of the Polymerase Chain Reaction (PCR) - Scottish Highers Human Biology - Question 2 - 2022

The enzyme used in step 3 is DNA polymerase, specifically Taq polymerase.

A heat tolerant form of DNA polymerase, such as Taq polymerase, ensures that the enzyme remains active during the high temperatures of the PCR process, allowing for multiple cycles of denaturation and amplification without needing to add more enzyme.

After 10 cycles of PCR, the number of DNA molecules produced can be calculated using the formula:

$N = N_0 imes 2^n$

where:

• $N_0$ is the initial number of DNA molecules (1),
• $n$ is the number of cycles (10).

So, $N = 1 imes 2^{10} = 1024$. Thus, 1024 DNA molecules are produced.