Multiple Choice
Which of the following is true regarding genomic genetic variations?
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4. DNA, Chromosomes, and Genomes
Human Genetic Variation
Multiple Choice
In the context of human genetic variation, what type of mutation causes sickle cell anemia (HbS) in the HBB gene?
A
A nonsense mutation that introduces a premature stop codon in β-globin
B
A large chromosomal deletion removing the HBB gene
C
A missense point mutation (single-nucleotide substitution) that changes one amino acid in β-globin
D
A frameshift mutation caused by a single-nucleotide insertion in HBB
Verified step by step guidance1
Understand the nature of sickle cell anemia at the molecular level: it is caused by a mutation in the HBB gene, which encodes the β-globin subunit of hemoglobin.
Recall that sickle cell anemia results from a single nucleotide change (point mutation) in the DNA sequence of the HBB gene, specifically a substitution of one base for another.
Recognize that this single nucleotide substitution leads to a change in one amino acid in the β-globin protein, altering its structure and function; this type of mutation is called a missense mutation.
Differentiate this from other mutation types: a nonsense mutation introduces a premature stop codon, a frameshift mutation results from insertions or deletions that shift the reading frame, and a large chromosomal deletion removes entire gene segments.
Conclude that the mutation causing sickle cell anemia is a missense point mutation that changes one amino acid in the β-globin protein, leading to the characteristic sickling of red blood cells.
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