Answer:
Yes, there is a specific mechanism or theory indicating that DNA breakage must occur and be repaired during DNA replication. DNA replication involves the unwinding of the double-stranded DNA molecule, separation of the strands, and the synthesis of new complementary strands from the existing ones. The process is catalyzed by DNA polymerases, which add nucleotides to the newly forming strand. However, DNA replication is not always perfect and errors can occur, leading to the introduction of mutations or damage in the DNA.
To prevent the propagation of these mutations to the next generation, DNA repair mechanisms have evolved to detect and correct these errors. One of the major types of DNA damage that DNA repair pathways can repair is double-strand breaks (DSBs). DSBs can be caused by various processes, including DNA replication, exposure to radiation or chemicals, and errors in DNA repair.
During DNA replication, DSBs can occur when the replication machinery encounters problems like DNA damage, lesions, or difficulties in replicating the repetitive ends of chromosomes. The broken ends of DNA are dangerous because they can lead to chromosome breakage and rearrangements that are associated with cancer and other genetic disorders. The cell machinery must repair these DNA breaks before the cell divides or undergoes apoptosis.
To repair DSBs, the cell employs one of two major pathways: non-homologous end-joining (NHEJ) or homologous recombination (HR). NHEJ is an error-prone mechanism that directly joins the two ends of broken DNA strands, while HR is a more precise mechanism that uses an undamaged, homologous DNA molecule as a template to repair the broken strand. These mechanisms ensure that the genome remains intact and properly replicated, preventing the accumulation of mutations and genetic diseases.
Step-by-step explanation: