Concept:
Mutations are changes in the DNA sequence. A point mutation is the simplest type of mutation involving a single nucleotide change.
Definition:
A point mutation is a genetic mutation in which a single nucleotide base is altered, inserted, or deleted in the DNA sequence. Most commonly, it involves substitution of one base for another.
Example: Sickle Cell Anemia Sickle cell anemia is a classic example of a point mutation affecting hemoglobin.
Cause:
- Mutation occurs in the gene encoding the -chain of hemoglobin.
- A single base substitution changes the codon.
Molecular Change:
This substitution changes one amino acid in the hemoglobin protein.
Effect:
- Hemoglobin becomes abnormal (HbS).
- RBCs become sickle-shaped under low oxygen conditions.
- Leads to anemia, pain, and reduced oxygen transport.
Significance:
- Demonstrates how a single nucleotide change can cause a major disorder.
- Example of a missense mutation.