In sickle cell disease, a single base substitution in the gene for haemoglobin changes one amino acid. This is an example of:
Answer and explanation
Correct answer: C. A point mutation that changes the amino acid sequence of the polypeptide
- Step 1: One nucleotide is replaced by another (substitution).
- Step 2: The new codon codes for a different amino acid (valine instead of glutamic acid), which changes haemoglobin's shape.
Answer
a point mutation changing one amino acid.
Why not the others: The number of chromosomes is unchanged; a frameshift needs an insertion or deletion; a silent change would keep the same amino acid.
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