Glycophorin A is a glycoprotein that extends across the red blood cell membrane. The portion of the polypeptide
that extends across the membrane bilayer contains 19 amino acid residues and is folded into a helix. What is the width of the bilayer that could be spanned by this helix? The interior of the bilayer includes long acyl chains that are nonpolar. Which of the 20 amino acids would you expect to find among those in the portion of the polypeptide that traverses the bilayer?