Question

carry oxygen throughout the body, and wonders whether hemoglobin is connected to the sickle - shaped cells. the technician learns that sickle cells are caused by a mutation in the hemoglobin gene. under low - oxygen conditions, the mutation reduces the ability of hemoglobin to bind oxygen, resulting in sickle - shaped rbcs. table 1 summarizes a mutation in the hemoglobin gene that causes sickle cells. table 1: sickle cell hemoglobin mutation

	normal hemoglobin	mutated hemoglobin
partial amino acid sequence	pro - glu - glu	pro - val - glu
hemoglobin structure	normal	abnormal
rbc shape in low - oxygen conditions	normal	sickle - shaped

which statement best describes the connection between the hemoglobin gene sequence and sickle - shaped rbcs?
a. several changes to the dna sequence lead to an abnormal hemoglobin protein, which causes rbcs to change shape under low - oxygen conditions.
b. low - oxygen conditions cause the hemoglobin gene to mutate, which then changes the protein structure of hemoglobin.
c. a single mutation in the dna sequence changes an amino acid in the hemoglobin protein, which causes rbcs to change shape under low - oxygen conditions.
d. low - oxygen conditions cause the hemoglobin protein to change shape, which then causes the

Explanation:

The table shows a single - base change in the DNA sequence (GAG to GTG) of the hemoglobin gene. This single - base mutation leads to a change in one amino acid (from Glu to Val) in the hemoglobin protein. This altered protein structure causes RBCs to become sickle - shaped under low - oxygen conditions.

Answer:

C. A single mutation in the DNA sequence changes an amino acid in the hemoglobin protein, which causes RBCs to change shape under low - oxygen conditions.