Question

Distinguish between the two DSB repair mechanisms we talked about in class in respect to their accuracy. What is the role of each of them in a survival of a cell?

A) Non-homologous end joining is more accurate than homologous recombination; both contribute to cell survival.
B) Homologous recombination is more accurate than non-homologous end joining; both are equally important for cell survival.
C) Both homologous recombination and non-homologous end joining have similar accuracy; their roles in cell survival are negligible.
D) Non-homologous end joining is error-prone, while homologous recombination is highly accurate; both are crucial for cell survival.

Answer 1

Homologous recombination (HR) is a highly accurate DNA repair mechanism, while non-homologous end joining (NHEJ) is more error-prone. Both are essential for cell survival, with HR maintaining genetic integrity and NHEJ providing a quick but less precise repair option. Their evolutionary significance lies in balancing fidelity with adaptability.

Step-by-step explanation:

Difference Between DNA Repair Mechanisms

In repair of double-strand breaks (DSB) in DNA, there are two principal mechanisms: non-homologous end joining (NHEJ) and homologous recombination (HR). These mechanisms differ significantly in their accuracy. Homologous recombination is an accurate repair process because it uses a sister chromatid or homologous chromosome as a template to ensure that the repair is precise and restores the original genetic information. This is crucial during meiosis where breakage and rejoining of DNA are required to exchange alleles between homologous chromosomes, fostering genetic diversity. Conversely, non-homologous end joining is a more error-prone process since it simply joins the broken DNA ends back together without the need for a template, which can result in insertions or deletions, altering the original genetic sequence.

Both mechanisms are critical for the survival of a cell. Homologous recombination is essential for accurate repair, particularly during cell division to maintain genetic integrity, while non-homologous end joining is often employed when a quick repair is necessary, such as in the case of immediate damage from ionizing radiation, despite its lower accuracy. These pathways highlight the evolutionary importance of maintaining the fidelity of genetic information as well as permitting adaptability and survival of species.