Question

refer to the passage and diagram. how do both the similarity and differences among amino acids allow them to form macromolecules with a wide variety of properties?
amino acids are named after two of their functional groups: the amino group (nh2), which acts like a base, and the carboxyl group (cooh), which acts like an acid. a third functional group, often called the r group, varies among the different types of amino acids. in alanine, the r group is a methyl group (ch3). in serine, the r group is a methyl alcohol (-ch2oh).
the presence of hydrogen groups and r groups allow any combination of amino acids to join together to form a polypeptide. the r groups are the same among all amino acids, and the determine the constituencies of the polypeptide or protein that is created.
the presence of amino groups and carboxyl groups allow any combination of amino acids to join together to form a polypeptide. the r groups differ among amino acids, and they determine the properties of the polypeptide or protein that is created.

Explanation:

Amino acids have common amino and carboxyl groups for linking together to form polypeptides. The variable R - groups give different properties to the resulting macromolecules.

Answer:

The presence of amino groups and carboxyl groups allow any combination of amino acids to join together to form a polypeptide. The R - groups differ among amino acids, and they determine the properties of the polypeptide or protein that is created.