Please answer in simplist terms possible... An individual has two copies of a si
ID: 276128 • Letter: P
Question
Please answer in simplist terms possible...
An individual has two copies of a sickle-cell allele of hemoglobin in which a (historical) mutation replaced the underlined A with a T. Explain how this change in genotype causes a change in phenotype. For full credit, address (1) the sequence of the protein, (2) the three-dimensional structure of the protein, and (3) the consequences for the red blood cells and the individual.
This is the answer I found, but I need it dumbed down to better understand if this answer is correct/would get full credit.
This change in one nucleotide produces a change in the amino acid sequence. Because of this a glutamine is changed to valine a hydro phobic amino acid at 6th position. This is called HbS sickle cell anemia hemoglobin. In high oxygen this hemoglobin works just fine and there is no change in the structure of the protein. But in low oxygen, this hemoglobin polymerizes with each other leading to formation fibrous patches. These fibrous patches consequently change the shape of the RBCs into a sickle shaped cell.
Explanation / Answer
WT Hemoglobin beta gene sequence: ACT CCT GAG GAG AAG TCT
Amino acid sequence: Thr Pro Glu Glu Lys Ser
Mutant Hemoglobin beta gene sequence: ACT CCT GTG GAG AAG TCT
Amino acid sequence: Thr Pro Val Glu Lys Ser
The mutation is located at the sixth codon position that converts glutamic acid to valine. It is a
i. Substitution mutation
ii. Missense mutation
iii. Nonsynonymous mutation
Since the mutation changes a polar amino acid (glu) with a nonpolar amino acid (val), the protein's structure is predisposed to alterations at low oxygen concentrations. AT high oxygen concentrations, the protein performs its physiological function normally. But, the protein polymerizes and forms long fibers at low oxygen concentrations. This leads to the sickling of RBC and compromised oxygen transport to the tissues.