Question

In a given DNA segment ATG ACC ACG ACC CCA ACA, the first base gets mutated. The effect of this on coding by this DNA segment will result in
a. A complete change in the type as well as sequence of amino acids.
b. Change in the first amino acid only.
c. No change in the sequence.
d. One amino acid less in the protein.
e. No coding occurs.

Answer 1

Hint: In the given DNA segment the first base gets mutated. This is the case of point mutation. The point mutation is defined as the change occurring within a particular gene at a particular time. This can be the case of base-pair mutation which can be either transition or transversion.

Complete answer:
• Point mutation involves alterations in the structure of a gene by altering the structure of DNA. There is an alteration in the normal base sequencing of a DNA molecule. This change may result in the modification of the structural characteristics of an individual.
• Here, there is a mutation in the first base only. This mutation will change the first base only.
• The base-pair mutation is defined as the mutation in which one base is substituted with the another in a DNA molecule. It can be of two types:
• Transition- In which a purine base is replaced by another purine and the pyrimidine base is replaced by another pyrimidine.
• Transversion- In which a purine base is changed by a pyrimidine base and vice versa
Therefore, in the above-given DNA segment when the first base gets mutated it will change the first amino acid only, the other type will remain the same.

Hence, the correct answer is option (B).

Note: Point mutation involves a base-pair mutation in which one base is substituted with the another in a DNA molecule and frameshift mutation in which there is a shift in the reading frame either backward or forward which can occur due to either deletion or insertion of nitrogenous bases.