Final answer:
Amino acids with small side chains, such as glycine, valine, alanine, and serine, are often found in situations where a small side chain is required to allow polypeptide chains to come near each other or make a right turn.
Step-by-step explanation:
Amino acids with small side chains, such as glycine, valine, alanine, and serine, are often found in situations where a small side chain is required to allow polypeptide chains to come near each other or make a right turn. These amino acids are commonly found in the secondary structure of proteins called beta sheets, where the alternate side chains point above and below in a 3-pleated sheet.