Question

Arrange the following in the proper sequence in which they occur during a single PCR cycle.

1. Addition of DNA nucleotides by Taq DNA polymerase.
2. Complementary base pairing between primers and target DNA.
3. Heat separation of strands of target DNA.

Answer 1

The correct order is 3 - 2 - 1

Step-by-step explanation:

In order for DNA replication to occur, both strands need to be separated so the polymerase can start adding nucleotides. In a PCR, this is achieved by an increase in temperature. After both strands are separated, a DNA primer binds the sequence from which the replication will start. This is because DNA polymerases need a short complementary sequence to attach to before they start replicating. Once both strands are separated and primers are paired to DNA, Taq Polymerase can start adding nucleotides to complete the cycle.