General Science • BiologyHard
What is the precise biochemical role of the enzyme DNA ligase during semi-conservative DNA replication in eukaryotic cells?
A. It unwinds the double helix by breaking hydrogen bonds between complementary nitrogenous bases.
B. It synthesizes short RNA primers required for DNA polymerase to initiate nucleotide addition.
C. It catalyzes the formation of phosphodiester bonds to covalently seal nicked sugar-phosphate backbones between Okazaki fragments on the lagging strand.✓ Correct Answer
D. It removes mismatched nucleotides from newly synthesized DNA strands during proofreading.
💡 Solution & Explanation
DNA ligase seals nicks in the sugar-phosphate backbone by catalyzing phosphodiester bond formation between adjacent 5-phosphate and 3-hydroxyl termini, effectively joining Okazaki fragments synthesized discontinuously on the lagging strand. Helicase unwinds the double helix, primase synthesizes RNA primers, and DNA polymerase elongates the new strands with high fidelity. DNA replication ensures accurate transmission of genetic information across cell divisions.
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