.gene mutation in which a single base pair in DNA has been changed
A mutation in which a single base pair in DNA has been changed is known as a point mutation. Point mutations are a type of gene mutation that can have various effects on an organism depending on where they occur and how they alter the genetic code.
There are several types of point mutations:
1. Silent mutation: The altered DNA sequence still codes for the same amino acid due to the redundancy in the genetic code, and thus the protein function is not affected.
2. Missense mutation: The change in the DNA sequence results in the coding for a different amino acid. This can have varying effects on the protein's function, from benign to deleterious, depending on the significance of the substituted amino acid in the protein structure or function.
3. Nonsense mutation: The single base change creates a premature stop codon, leading to a truncated and typically nonfunctional protein.
4. Frameshift mutation: While not a change in a single base, but rather an insertion or deletion of a base (indel), a frameshift mutation changes the reading frame from the point of mutation, potentially altering every downstream amino acid in the protein. Frameshift mutations can be particularly devastating to protein function.
These point mutations can occur due to various factors such as errors during DNA replication, exposure to mutagens (such as chemicals or UV radiation), or spontaneously. Some point mutations may have little to no effect on the organism, while others can be the cause of diseases or contribute to the development of cancer.