What is a characteristic of proteins?

• A. Proteins are assembled from nucleotides.
• B. Proteins are used to store glucose.
• C. Proteins are made of amino acids and help build muscles, skin, bones, tissue, and organs.
• D. Proteins are hydrophobic.

Answer: (C)

Proteins are polymers made from amino acids linked by peptide bonds, and they play many structural and functional roles in the body. That makes the statement that proteins are made of amino acids and help build muscles, skin, bones, tissue, and organs the best description. It reflects both what proteins are built from and how they contribute to the body's structure—think of collagen strengthening skin and bones, or actin and myosin enabling muscle contraction, along with other proteins forming tissues and organs.

The other ideas don’t fit as a general characteristic: nucleotides form nucleic acids like DNA and RNA, not proteins; glucose storage is handled mainly by glycogen (a carbohydrate), not proteins; and labeling proteins as hydrophobic oversimplifies their nature—proteins have surfaces with both hydrophilic and hydrophobic regions, depending on their amino acid makeup.