Should be A the newer layers are usually on top
Answer:
Explanation:
The above mentioned key points are mechanisms by which cells used to correct replication error and repair damaged DNA.
Proof Reading: while printing a page, the typesetter set the types and impression is taken, proof reading is done to correct mistakes if any, and the final printing is done. A similar follow up mechanism is done after DNA synthesis. If DNA polymerase detects an incorrect nucleotide pair, it will remove and replace with the correct nucleotide immediately.
Mismatch Repair:even after DNA synthesis, mismatch area(insertion or deletion) can be identified on the newly synthesized DNA.
In the mismatch repair, specific proteins scan the newly synthesized DNA strand. The mismatch area is identified and loop.
The second protein complex remove the mismatch segment. Finally correct segment is synthesized by the help of DNA polymerase, SSBs and ligase.
DNA damage repair mechanism: when DNA get damaged, there's a repair process that fix the damage. This includes Direct reversal, excision repair and Double stranded break repair
