Question

"Which statement is true of the side chains that occur in proteins?

(a) Some of them contain only C and H.
(b) Some of them contain carboxyl groups.
(c) None of them join the backbone at more than one point.
(D) Both (a) and (b).
(e) All the above."

Answer 1

Side chains in proteins can contain only carbon and hydrogen or include carboxyl groups. They connect to the protein backbone at a single point, the alpha-carbon. Hence, the correct answer is (D) Both (a) and (b).

Step-by-step explanation:

When examining the side chains that occur in proteins, several statements can be made about their characteristics. Firstly, some side chains may consist purely of carbon (C) and hydrogen (H), such as those found in nonpolar amino acids like alanine. Secondly, others may include carboxyl groups, which is evident in the side chains of amino acids like glutamic acid. Importantly, each side chain connects to the protein backbone at the alpha-carbon, but not more than this single point. Therefore, the correct statement about protein side chains is that both (a) and (b) are true. The variability of the side chains, including size, shape, and functional groups, contributes to the unique properties of each amino acid, ultimately affecting the protein's structure and function.