Which of the following statements correctly describes proteins?

• A. Proteins are polymers made of amino acid monomers.
• B. Proteins are composed of nucleotides linked by phosphodiester bonds.
• C. Proteins function as enzymes, structural components, and signaling molecules.
• D. Proteins are the primary source of genetic information in cells.

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the structure of proteins. Proteins are polymers made up of amino acid monomers. Amino acids are linked together by peptide bonds, forming polypeptide chains that fold into specific three-dimensional structures.
2. Step 2: Clarify the incorrect statement about proteins being composed of nucleotides linked by phosphodiester bonds. This description applies to nucleic acids (DNA and RNA), not proteins. Proteins are made of amino acids, not nucleotides.
3. Step 3: Explore the functions of proteins. Proteins serve diverse roles in the cell, including acting as enzymes to catalyze biochemical reactions, providing structural support (e.g., collagen in connective tissues), and functioning as signaling molecules (e.g., hormones like insulin).
4. Step 4: Address the incorrect statement about proteins being the primary source of genetic information. Genetic information is stored in DNA, not proteins. Proteins are involved in expressing genetic information but do not store it.
5. Step 5: Summarize the correct descriptions of proteins: Proteins are polymers of amino acids linked by peptide bonds, and they perform essential functions such as enzymatic activity, structural support, and cell signaling.