Question

What is the purpose of raising the temperature to 90-95°C at the beginning of each cycle of PCR?

1) To renature two single DNA strands
2) To attach the primer
3) To extend the primer
4) To separate the double-stranded DNA

Answer 1

The purpose of elevating the temperature to 90-95°C in PCR is to denature double-stranded DNA, allowing strands to separate and facilitate subsequent annealing of primers and extension by DNA polymerase in other temperature-specific steps of the cycle.

Step-by-step explanation:

The purpose of raising the temperature to 90-95°C at the beginning of each cycle of PCR is to separate the double-stranded DNA. This first step, known as denaturation, involves heating the DNA to break the hydrogen bonds holding together the two strands, resulting in two single strands. Following denaturation, the temperature is then lowered to allow the primers to anneal (attach) to the single-stranded DNA at a lower temperature. The last step involves extending the primers with a DNA polymerase at an intermediate temperature optimal for the enzyme.