HbS has normal shape under normal conditions, but under conditions of low [O2] the hemoglobin forms fibrous aggregations, giving the entire red blood cell a sickle shape. (See image of eight HbS molecules at right.) Sickled red blood cells are relatively inflexible and may clog capillary beds, causing pain and tissue damage. The red blood cells also have a shorter life span, leading to anemia.

(a) Which of the following amino acids would you expect to produce a similar sickling effect if placed at position 6? Select all that apply.

a)aspartate

b)lysine

c)glycine

d)leucine

e)arginine