milar to each other than sequences from more distantly related species. In this exercise, you will look at amino acid sequence data for the _ polypeptide chain of hemoglobin, often called _-globin. You will then interpret the data to hypothesize whether the monkey or the gibbon is more closely related to humans. In the alignment shown here, the letters give the sequences of the 146 amino acids in _-globin from humans, rhesus monkeys, and gibbons. Because a complete sequence would not fit on one line, the sequences are broken into segments. The sequences for the three different species are aligned so that you can compare them easily. For example, you can see that, for all three species, the first amino acid is "V" (valine) and the 146th amino acid is "H" (histidine). Click on the alignment to view it at a larger size. Scan along the aligned sequences, letter by letter, noting any positions where the amino acids in the monkey or gibbon sequences do not match the human sequence. How many amino acids differ between the monkey and the human sequences?