Problem:
As we know, the DNA has more stability than RNA, if one chain has broken or accidentally distorted, it can be repaired by the other one.
Suppose there is a segment AGTC, its peer is GACT. Now its peer get distorted to TACT, so the DNA will replace the wrong T to G.
Required:
Question: Why doesn't the DNA replace the A to C in the first chain?
Question: How does the DNA know the first chain is correct and the second one is incorrect?
Please provide discription of all the answers.