A mutation that changes one base pair in the DNA sequence is called a: –
(A) Frameshift mutation
B) Point mutation
C) Deletion mutation
D) Duplication mutation
The correct answer and explanation is:
The correct answer is B) Point mutation.
A point mutation refers to a genetic change that involves a change in a single base pair in the DNA sequence. This alteration can occur through various mechanisms, such as substitution, where one base is replaced by another, or through a shift in the genetic code that may cause a change in protein synthesis. Point mutations can be classified into three main types: silent, missense, and nonsense mutations.
- Silent mutations do not result in any change in the protein because the altered codon still codes for the same amino acid due to the redundancy of the genetic code.
- Missense mutations lead to the substitution of one amino acid for another in the protein sequence, which may or may not affect the protein’s function.
- Nonsense mutations introduce a premature stop codon, leading to a truncated, usually nonfunctional protein.
On the other hand, a frameshift mutation (A) involves the insertion or deletion of a nucleotide, which shifts the reading frame of the codons and can drastically alter the protein produced. A deletion mutation (C) refers to the loss of one or more nucleotides, while a duplication mutation (D) refers to the repetition of a section of DNA. Both deletion and duplication mutations can lead to significant changes in the genetic sequence but typically involve more than a single base pair change.
Thus, a point mutation is the term used when only one base pair is altered, which distinguishes it from the more dramatic changes seen in frameshift, deletion, or duplication mutations. Point mutations can have a wide range of effects on the organism, from no effect at all to causing serious genetic diseases depending on the location and nature of the mutation.