Protein molecules are usually quite large and yet often water-soluble. They are soluble in water because they can fold themselves into spherical shapes in which the polar (hydrophilic) side chains are on the surface and the nonpolar (hydrophobic) side chains are buried inside the sphere. Of the amino acids Ala, Ser, Phe, Ile, Arg, and Asp, 

(a) Which would you expect to find on the surface of a water-soluble protein?

(b) Which would you expect to find buried deep inside the protein structure?

(c) Which might be in either location depending on the solution pH?