Which of the following best describes the complete sequence of steps occurring during every cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double-stranded target DNA. 3. Fresh DNA polymerase is added. 4. DNA polymerase extends the primers to make a copy of the target DNA. 2, 1, 4 3, 4, 2 3, 4, 1, 2 2, 3, 4 1, 3, 2, 4

2, 1, 4, 3

Explanation:

2

Denaturation by Heat to separate double-stranded DNA into two single strands

1

Annealing Primer to Target Sequence

The primers that anneal (bind) to the complementary sequence marks the DNA target sequence

4

Extension

New double stranded DNA molecules that is identical to the original double stranded target DNA region is formed

3

End of the First PGR Cycle

Fresh DNA polymerase is added