Amino Acid Biochemistry:

Amino acids are arrayed towards the interior or exterior of a globular folded protein, depending on their relative affinity for water.

For each of the following pairs of amino acids, choose the one that is more likely to be found in the interior (or at least towards the interior) of a protein molecule, and give a chemical explanation as to why:

a. Alanine:glycine

b. tyrosine: phenylalanine

c. serine: cysteine

d. tryptophan: phenylalanine