Question

If the “annealing” step is missed during PCR, what would be its effect on the entire process?

• A. DNA strands will not separate.
• B. Primers will not attach.
• C. DNA Polymerase would not work.
• D. DNA will not extend.

Answer 1

Answer: (B), (C), (D)

DNA will not extend.

PCR occurs in three steps:

1. Denaturation: It maintains a temperature at 94$°$C. The high temperature melts the hydrogen bonds and separates the two strands of DNA.
2. Anealing: It occurs at 55$°$C. The two oligonucleotide primers anneal with the separate strands.
3. Extension: It carries out at 72$°$C. Finally, DNA polymerase froms the complimentary strand.

Hence if the "Annealing" step is missed the primers will not attach. DNA polymerase cannot function without a primer and therefore DNA will not extend.