Question

The DNA sequence AAAGGGCCCCGGGCCCC could be considered a mutational hot spot because

Group of answer choices

it contains more G/C than A/T and therefore is unstable.

it is repetitive and therefore would be shortened with each cell division.

it is repetitive and therefore more prone to errors during replication and repair.

it contains more G/C than A/T and therefore is difficult to transcribe.

Answer 1

The correct option is the third one

Whenever, DNA synthesis happens and DNA polymerase encounters any repetitive sequence. Then chances of mutation by replication slippage increases. At repetitive sequence region of DNA like in microsatellite area, tandem repeats are present in very high number and when DNA polymerase replicates such area then slippage led insertion or deletion mutations happens frequently.

Since DNA synthesis not only happens in DNA replication but also happens during various type of DNA repair like mismatch repair. So, during repair of repetitive sequences again polymerase slippage can happen. Therefore, the given DNA sequence is mutational hot spot because of error in DNA synthesis and repair.

First option is incorrect- Since G and C bind with triple hydrogen bond. They are considered more stable. So, this argument does not explain high mutation rate.

Second option is incorrect as Shortening happens only in the terminal end point of chromosome or in telomeric repeats. There is no such thing mentioned here. hence. this option is also incorrect.

Fourth option is also incorrect- There is no effect of high GC content during transcription. Hence, this option is also incorrect.