[Campbell Biology P.375] If a bacterium has a mutated DNA ligase that is non-functional, whi... | Practice Question

If a bacterium has a mutated DNA ligase that is non-functional, which of the following would be the most direct consequence during DNA replication?

  • A: The DNA double helix would fail to unwind.
  • B: RNA primers would not be synthesized.
  • C: Okazaki fragments would be synthesized but would remain unjoined.
  • D: DNA polymerase III would be unable to add new nucleotides.

Explanation

DNA ligase is responsible for forming the final phosphodiester bond to join adjacent Okazaki fragments on the lagging strand. If DNA ligase is non-functional, the Okazaki fragments would be synthesized by DNA polymerase III and the primers would be removed and replaced by DNA polymerase I, but the nicks gaps between the fragments would remain unsealed, leading to fragmented DNA.