Sickle cell anaemia results from a change in the nucleotide sequence of a single gene. This kind of change is best classified as which type of mutation?

1. Mutations are of two main kinds: chromosomal and gene mutations. 2. A change in the nucleotide sequence of a single gene is a gene or point mutation. 3. Sickle cell anaemia is caused by such a single-gene change altering the haemoglobin protein. 4. Chromosomal mutation changes the structure or number of chromosomes, not a single gene, which rules out option A. 5. So this is a gene or point mutation, option C. _Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 18 Genetics "Gene or point mutation", p.277_