Which is a point mutation and not a frameshift mutation?
mutagen
insertion
deletion
silent
The Correct Answer and Explanation is :
The correct answer is silent mutation.
Explanation of Mutations:
Mutations are changes in the DNA sequence that can lead to alterations in the structure and function of proteins. There are several types of mutations, including point mutations and frameshift mutations.
1. Point Mutation:
A point mutation involves a change in a single nucleotide base pair. It can be categorized into three types:
- Silent Mutation: This occurs when a change in a nucleotide does not alter the amino acid sequence of the resulting protein. For example, if the codon GAA (which codes for glutamic acid) changes to GAG, the amino acid sequence remains the same, since both codons code for the same amino acid. Silent mutations typically occur in the third position of a codon due to the redundancy of the genetic code.
- Missense Mutation: This is a type of point mutation where a single nucleotide change results in a codon that codes for a different amino acid, potentially affecting protein function.
- Nonsense Mutation: In this case, a point mutation results in a stop codon, leading to the premature termination of the protein synthesis, which can result in a nonfunctional protein.
2. Frameshift Mutation:
Frameshift mutations, on the other hand, result from the insertion or deletion of nucleotides in numbers other than three, which alters the reading frame of the genetic code. This change can lead to a completely different translation from the original, often producing a nonfunctional protein. For instance, if one nucleotide is deleted or added, all subsequent codons are shifted, which can drastically change the amino acid sequence downstream of the mutation.
In summary, a silent mutation is a type of point mutation where the genetic change does not impact the amino acid sequence of a protein, while insertion and deletion mutations lead to frameshifts that disrupt the normal reading of the genetic code.