AP BIOLOGY

Detailed explanation-1: -There is substantial biochemical evidence indicating that DNA ligase I, which is one of four DNA ligases in mammalian cells (1, 2), is the enzyme responsible for joining Okazaki fragments.

Detailed explanation-2: -DNA ligases are best known for their role in joining adjacent Okazaki fragments at the lagging strand of the replication fork; however, they are essentially involved in any process that requires sealing of phosphodiester bonds from the DNA backbone.

Detailed explanation-3: -Ligase is an enzyme that joins the two strands of DNA together. It is used to join the Okazaki fragments that are produced on the lagging strand of the replication fork.

Detailed explanation-4: -Enzyme ligase connects (ligates) the two Okazaki fragments into one continuous newly synthesized complementary strand. DNA ligase I-DNA ligase I connects the Okazaki fragments during the synthesis. Hence, the correct option is option C, ‘Ligase’.