0
$\begingroup$

Suppose we have one strand with 3'-AAA-5' and the other strand is 5'-TTT-3'.

So when point mutation occurs, does it happen to two strands at the same time? e.g. 3'-AAA-5' becomes 3'-AGA-5' and 5'-TTT-3' becomes 5'-TCT-3'?

Or the mutation can occur with only one strand? e.g. only 3'-AAA-5' becomes 3'-AGA-5'? but in this case, A would pair up with G.

When transcription starts, the 3'-5' strand is transcribed, if the mutation does no occur in this strand, does it mean this mutation wouldn't affect any downstream products?

Is it same for indel?

$\endgroup$
1
$\begingroup$

A "mutation" is a permanent alteration of the genetic composition of an individual. To obey this definition, a base change in one strand must be accompanied by a corresponding change in the opposite strand. Only in this way a mutation can be transmitted to the offspring.

The situation where only one of the strands has undergone a base change constitutes a pre-mutational DNA damage, as the double strand will show a deformation at that site. The enzymes of DNA repair mechanisms recognize and correct many such "deformations", but sometimes they do not know which was the original base, and introduce a change that become fixed in the DNA sequence.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.