What would be the first step in using PCR to copy a gene?

a. DNA polymerase adds nucleotides to separate strands.

b. Various strands of DNA are allowed to cool.

c. DNA is heated to seperate stands.

d. Copied strands are used as templates to make more copies.

The correct answer is C.

During the first step of PCR, called denaturation, the tube containing the sample of DNA is heated to more than 90 degrees Celsius (194 degrees Fahrenheit) which separates the double-stranded DNA into two separate strands. The high temperature breaks the relatively weak bonds between the nucleotides that form DNA.

PCR stands for Polymerase Chain Reaction. It is an efficient and cost effective way to copy or amplify small segments of DNA or RNA, now in wide use.