Final answer:
During DNA replication, Okazaki fragments are linked together by DNA ligase, not DNA gyrase, which creates phosphodiester bonds between the fragments. DNA gyrase relieves torsional strain ahead of the replication fork, but DNA ligase is responsible for joining the fragments into a continuous strand.
Step-by-step explanation:
During DNA replication, Okazaki fragments are linked together by DNA ligase, an enzyme that creates phosphodiester bonds between nicked fragments of DNA. Okazaki fragments are short strands of DNA that are synthesized on the lagging strand during DNA replication. The process begins with the unwinding of the DNA double helix by the enzyme helicase. As the replication fork progresses, the lagging strand is synthesized in a discontinuous manner, forming Okazaki fragments.
DNA primase adds an RNA primer to the newly exposed DNA template strand, which DNA polymerase then uses to synthesize the Okazaki fragments. After synthesis, another enzyme, DNA polymerase I, removes the RNA primers and fills in the gap with DNA nucleotides. Finally, DNA ligase comes into play, sealing the fragments into a continuous DNA strand by forming a phosphodiester linkage between the 3'-OH of one end and the 5'-phosphate of another. This covalent bond ensures the structural integrity of the newly synthesized lagging strand.
It's important to note that this vital role in DNA replication is distinctly attributed to DNA ligase and not DNA gyrase. DNA gyrase, also known as topoisomerase II, is involved in relieving torsional strain that arises ahead of the replication fork as the DNA helix unwinds. Together, these enzymes ensure accurate and efficient replication of the DNA molecule, which is crucial for cell division and inheritance.