Which best describes the primary role of ligase in DNA replication?

Which best describes the primary role of ligase in DNA replication?

• A. Binds RNA primers to DNA
• B. Joins Okazaki fragments together
• C. Unwinds DNA strands
• D. Creates RNA primers

Answer: (B)

In the context of DNA replication, ligase serves a critical function by joining Okazaki fragments together. During the replication of the lagging strand, DNA is synthesized discontinuously in small segments known as Okazaki fragments. As replication progresses, each fragment is synthesized when RNA primers are laid down, allowing DNA polymerase to extend the strands. However, there are gaps between these fragments once synthesis is complete. DNA ligase is the enzyme responsible for sealing these gaps by forming phosphodiester bonds between the 3' end of one Okazaki fragment and the 5' end of the next. This enzymatic action effectively creates a continuous strand of DNA, which is essential for maintaining the integrity and continuity of the genetic material during cell division. The other roles outlined in the options are attributed to different enzymes in the DNA replication process. For instance, binding RNA primers to DNA is the function of primase, unwinding DNA strands is the role of helicase, and creating RNA primers is also the task of primase. Thus, ligase's primary role in joining Okazaki fragments is vital for the proper completion of DNA replication on the lagging strand.

In the context of DNA replication, ligase serves a critical function by joining Okazaki fragments together. During the replication of the lagging strand, DNA is synthesized discontinuously in small segments known as Okazaki fragments. As replication progresses, each fragment is synthesized when RNA primers are laid down, allowing DNA polymerase to extend the strands. However, there are gaps between these fragments once synthesis is complete.

DNA ligase is the enzyme responsible for sealing these gaps by forming phosphodiester bonds between the 3' end of one Okazaki fragment and the 5' end of the next. This enzymatic action effectively creates a continuous strand of DNA, which is essential for maintaining the integrity and continuity of the genetic material during cell division.

The other roles outlined in the options are attributed to different enzymes in the DNA replication process. For instance, binding RNA primers to DNA is the function of primase, unwinding DNA strands is the role of helicase, and creating RNA primers is also the task of primase. Thus, ligase's primary role in joining Okazaki fragments is vital for the proper completion of DNA replication on the lagging strand.