[Campbell Biology P.377] Which of the following sequences correctly describes the steps invo... | Practice Question

Which of the following sequences correctly describes the steps involved in nucleotide excision repair of DNA damage, as depicted in Figure 16.20?

  • A: Detection by enzymes → DNA ligase seals → Nuclease cuts → DNA polymerase fills.
  • B: Nuclease cuts → Detection by enzymes → DNA polymerase fills → DNA ligase seals.
  • C: Detection by enzymes → Nuclease cuts → DNA polymerase fills → DNA ligase seals.
  • D: DNA polymerase fills → Nuclease cuts → Detection by enzymes → DNA ligase seals.

Explanation

Nucleotide excision repair begins with enzymes detecting the damaged DNA Step 1 . A nuclease then cuts the damaged strand and removes the section Step 2 . DNA polymerase synthesizes new DNA to fill the gap using the undamaged strand as a template Step 3 . Finally, DNA ligase seals the newly synthesized DNA to the old DNA, completing the repair Step 4 . This sequence is clearly illustrated in Figure 16.20.