Final answer:
Nonhomologous end joining is a DNA repair mechanism that fixes double-stranded breaks by deleting the damaged sections and rejoining the DNA ends. It is a crucial repair process that operates independently of sequence homology and is critical for maintaining genetic stability.
Step-by-step explanation:
Nonhomologous end joining (NHEJ) is a mechanism that repairs double-stranded breaks in DNA. This can be caused by DNA replication errors or by environmental factors such as ionizing radiation or oxidation. The process involves the deletion of the damaged DNA and any adjacent DNA, followed by the rejoining of the cut ends. This pathway is independent of sequence homology, which means that it does not require a template strand to guide the repair, as is the case in homologous recombination.
Lagging strand replication, which occurs in short fragments known as Okazaki fragments, and leading strand synthesis, which is continuous, are both processes that involve DNA replication and repair mechanisms. NHEJ, in particular, is critical for repairing breaks on both strands that occur during replication. Mismatch repair is another DNA repair mechanism that targets single base mismatches, as opposed to the more complex double-stranded breaks repaired by NHEJ. It recognizes and repairs incorrect nucleotides inserted during DNA replication, thus maintaining the integrity of the genetic code.