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 in the HBB gene causes sickle cell disease?
A
A chromosomal translocation involving the HBB locus that creates a fusion gene
B
A missense point mutation (single-nucleotide substitution) that changes a codon and substitutes one amino acid in the beta-globin protein
C
A frameshift mutation caused by a single-nucleotide insertion that shifts the reading frame of HBB
D
A nonsense mutation that introduces a premature stop codon in HBB, producing a truncated beta-globin protein
Verified step by step guidance1
Understand the role of the HBB gene: The HBB gene encodes the beta-globin subunit of hemoglobin, which is crucial for oxygen transport in red blood cells.
Recall the types of mutations: Missense mutations change one amino acid in the protein, nonsense mutations introduce a premature stop codon, frameshift mutations alter the reading frame, and chromosomal translocations rearrange large DNA segments.
Identify the mutation causing sickle cell disease: It is a single-nucleotide substitution (point mutation) in the HBB gene that changes one codon, resulting in the substitution of one amino acid in the beta-globin protein.
Recognize the specific amino acid change: This missense mutation replaces glutamic acid with valine at the sixth position of the beta-globin chain, altering the protein's properties and causing sickling of red blood cells.
Conclude that the mutation type is a missense point mutation, not a frameshift, nonsense, or chromosomal translocation mutation.
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