Question

There are two broad categories of base substitutions based on whether the new base is similar to the old one. a change of ata to aca would be categorized as a

a) Transition
b) Transversion

Answer 1

The mutation from ata to aca involves replacing one purine (adenine) with another purine (adenine), and this kind of base substitution is defined as a transition. Therefore, the correct categorization for this type of mutation is a transition.

Option A is the correct answer.

Step-by-step explanation:

When discussing types of single nucleotide mutations, or point mutations, there are two primary categories to consider: transitions and transversions.

A transition is when a purine is replaced by another purine, for example, adenine (A) is replaced by guanine (G), or when a pyrimidine is replaced by another pyrimidine, such as cytosine (C) is replaced by thymine (T). On the other hand, a transversion occurs when a purine is replaced by a pyrimidine or vice versa, for instance, cytosine (C), a pyrimidine, is replaced by adenine (A), a purine.

Referring to the student's question, the mutation from ata to aca involves the replacement of a purine (adenine) with another purine (adenine). Therefore, this type of base substitution is categorized as a transition, as the new base is similar to the old one in that they are both purines. Hence, the correct option is (a) Transition.