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.
10. Based on Table 1, how many different P-type globins and how many different Q-type globins, respectively, are found among the 3 human Hb variants?
Your Answer is
Correct Answer is G
Explanation
The last sentence of the first paragraph explains how to determine P and Q. Combined with table 1, it can be seen that there are two elements of P-type, namely ζ and α, and four elements of Q-type are ε, γ, β, σ