Passage II
In red blood cells (RBCs), the protein hemoglobin (Hb) carries oxygen. Each Hb molecule contains 4 globin polypeptides一a pair of P-type globins and a pair of Q-type globins. The possible combinations of the P-type globin and the Q-type globin for the 3 variants of human Hb are shown in Table 1. For each combination, the notation is of the form (P-type)2(Q-type)2.
Figure 1 shows the sites of RBC production during early human development (gestation through 48 weeks after birth). The figure also shows, over that time period, what percent of the total number of globin polypeptides produced are ζ, ε, γ, α, β, or δ globin polypeptides.
Table and figure adapted from Robert L. Nussbaum, Roderick R. Mclnnes, and Huntington F. Willard, Thompson & Thompson Genetics in Medicine, 6th edition. @2004 by Elsevier.
9. According to the information given, which Hb variant, Hb2 or Hb3, is more abundant in RBCs from 12 weeks to 24 weeks of gestation?
Your Answer is
Correct Answer is B
Explanation
Pay special attention to the question asking about 12-24 weeks of gestation, not weeks after birth. It can be seen from Figure 1 that the amount of γ globin is much larger than that of β globin