Which enzyme creates a chemical bond between Okazaki fragments on the lagging strand?

Which enzyme creates a chemical bond between Okazaki fragments on the lagging strand?

• A. DNA ligase
• B. DNA polymerase
• C. Helicase
• D. Primase

Answer: (A)

DNA ligase is the enzyme that completes the lagging strand by forming the covalent phosphodiester bonds that join adjacent Okazaki fragments. The lagging strand is made in short pieces, each starting with an RNA primer laid down by primase and extended by DNA polymerase. After the primers are removed and the gaps filled with DNA, ligase seals the nicks between fragments, stitching them into a continuous strand. This bond formation requires energy, typically from ATP in eukaryotes. Helicase unwinds the DNA, primase lays down primers, and polymerase builds the DNA but does not seal fragments.

DNA ligase is the enzyme that completes the lagging strand by forming the covalent phosphodiester bonds that join adjacent Okazaki fragments. The lagging strand is made in short pieces, each starting with an RNA primer laid down by primase and extended by DNA polymerase. After the primers are removed and the gaps filled with DNA, ligase seals the nicks between fragments, stitching them into a continuous strand. This bond formation requires energy, typically from ATP in eukaryotes. Helicase unwinds the DNA, primase lays down primers, and polymerase builds the DNA but does not seal fragments.