Question

What must occur for 5BU to cause a transition mutation?

Answer 1

For 5BU (5-bromouracil) to cause a transition mutation, it must undergo tautomeric shift.

Step-by-step explanation:

5-bromouracil (5BU) is a chemical analog of thymine that can be incorporated into DNA during replication. To induce a transition mutation, 5BU must undergo a tautomeric shift. Tautomeric shifts involve the reversible movement of a hydrogen atom within a molecule, leading to the formation of alternative structures known as tautomers. In the case of 5BU, the tautomeric shift can result in the formation of enol tautomers, causing it to temporarily resemble guanine rather than adenine.

During DNA replication, if the enol form of 5BU is present, it can base-pair with adenine instead of thymine. This mispairing can lead to a transition mutation, where a purine is substituted for another purine or a pyrimidine is substituted for another pyrimidine.