What is the role of DNA ligase in molecular biology?

DNA ligase plays a critical role in the process of DNA replication and repair by facilitating the joining of DNA fragments. During DNA replication, particularly in the lagging strand, DNA is synthesized in short segments known as Okazaki fragments. These fragments are synthesized discontinuously, resulting in segments that are not physically connected to each other. DNA ligase acts to connect these fragments by forming phosphodiester bonds between the sugar and phosphate backbone of adjacent nucleotides.

This joining process is essential for creating a continuous and stable DNA strand, which is required for proper DNA function and integrity. Without DNA ligase, the fragments would remain separate, preventing the completion of DNA replication and hindering the overall stability of the DNA molecule.

The other options do not accurately describe the function of DNA ligase: DNA ligase does not break hydrogen bonds, add methyl groups, or induce gene silencing. Its primary and well-established role involves the ligation of DNA fragments, making it crucial for the maintenance and replication of genetic material. This versatility is why the function of DNA ligase is fundamental in various molecular biology applications, including cloning and DNA repair mechanisms.