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9. Replacement of an A by a T in a region of the human gene for the B chain of h

ID: 78558 • Letter: 9

Question

9. Replacement of an A by a T in a region of the human gene for the B chain of hemoglobin is associated with sickle-cell anemia:

Normal: 5-ATGGTGCACCTGACTCCTGAGGAGAAGTCT-3

Sickle cell: 5-ATGGTGCACCTGACTCCTGTGGAGAAGTCT-3

(a) What is the nucleotide sequence of the normal and sickle-cell hemoglobin mRNA?

(b) What is the amino acid sequence in this part of the Bpolypeptide chain, and what is the amino acid replacement that results in sickle-cell hemoglobin?

(c) Why might this amino acid substitution make a difference in protein structure?

Explanation / Answer

Normal chain= AUGGUGCACCUGACUCCUGAGGAGAAGUCU

Sickle cell anemia chain=AUGGUGCACCUGACUCCUGUGGAGAAGUCU

Normal chain= MVHLTPEKS

Sickle cell anemia chain=MVHLTPEKS