Asked by amaya battle
sickle cell hemoglobin DNA: CACGTAGACTGAGGACAC
sickle cell hemoglobin mRNA: GUGCAUCUGACUCCUGUG
sickle cell hemoglobin AA sequence: Val His Leu Thr Pro Val
What type of mutation is this? Please explain why.
All Answers 1
Answered by
GPT-5 mini
AI
This is a missense point mutation (a single‑base substitution) — specifically the classic sickle‑cell Glu→Val (E6V) change.
Why:
- Wild‑type mRNA for the first six residues would read: GUG CAU CUG ACU CCU GAG → Val His Leu Thr Pro Glu.
- The provided mutant mRNA is: GUG CAU CUG ACU CCU GUG → Val His Leu Thr Pro Val.
- Only the sixth codon changed: GAG (Glu) → GUG (Val). That change is caused by a single nucleotide substitution in the DNA (A → T in the coding strand, an A→U change in the mRNA).
- Because one amino acid is replaced by a different one (acidic Glu → hydrophobic Val), it is a nonsynonymous (missense) mutation; it is not a frameshift, nonsense, or silent mutation.
This specific missense substitution (E6V) is the molecular basis for sickle‑cell hemoglobin (HbS), which alters hemoglobin properties and causes polymerization of deoxygenated Hb.
Why:
- Wild‑type mRNA for the first six residues would read: GUG CAU CUG ACU CCU GAG → Val His Leu Thr Pro Glu.
- The provided mutant mRNA is: GUG CAU CUG ACU CCU GUG → Val His Leu Thr Pro Val.
- Only the sixth codon changed: GAG (Glu) → GUG (Val). That change is caused by a single nucleotide substitution in the DNA (A → T in the coding strand, an A→U change in the mRNA).
- Because one amino acid is replaced by a different one (acidic Glu → hydrophobic Val), it is a nonsynonymous (missense) mutation; it is not a frameshift, nonsense, or silent mutation.
This specific missense substitution (E6V) is the molecular basis for sickle‑cell hemoglobin (HbS), which alters hemoglobin properties and causes polymerization of deoxygenated Hb.
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