Question

Which of the following best describes the SOS repair system?

A. By-pass or tolerance system that allows DNA replication across damage areas at the cost of fidelity.

B. Repair system based on the variation of the nonhomologous end joining mechanism.

C. Repair system that recognizes which strand is the parental strand, and which is the daughter, and fixes mutations in the new strand.

D. It is a system in eukaryotes, which uses photoreactivation to directly repair thymine dimers.

Answer 1

Option (A), The SOS repair system is a tolerance mechanism that allows DNA replication across damaged areas with reduced fidelity, increasing survival but at the cost of higher mutation rates.

Step-by-step explanation:

The SOS repair system best describes as A. By-pass or tolerance system that allows DNA replication to proceed across areas of damage at the cost of fidelity. This system enables cells to survive by tolerating DNA damage rather than repairing it, leading to an increase in mutation rates as DNA replication skips over damaged segments.

Different from the precise mechanisms like nucleotide excision repair and mismatch repair, the SOS repair system does not rely on an undamaged template strand for accurately correcting errors. Instead, it involves a trade-off between survival and maintaining genetic fidelity. This system is a key aspect of DNA damage tolerance strategies in prokaryotes and helps cells cope with extensive DNA damage that otherwise might stall replication forks.