Which molecule serves as the building block of proteins?

Which molecule serves as the building block of proteins?

• A. Amino acids
• B. Nucleotides
• C. Monosaccharides
• D. Fatty acids

Answer: (A)

Proteins are polymers built from amino acids. The sequence and linkage of amino acids via peptide bonds form a polypeptide chain that folds into functional proteins. Each amino acid has an amino group, a carboxyl group, a central carbon, a hydrogen, and a side chain (R group) that imparts unique properties. During translation, the ribosome assembles amino acids in the order specified by mRNA, delivering them through tRNA so that the carboxyl group of one amino acid bonds to the amino group of the next, creating the growing chain with a free N-terminus and C-terminus. The variety of side chains among amino acids drives the structure and function of proteins. Nucleotides form nucleic acids (DNA and RNA), monosaccharides form carbohydrates, and fatty acids form lipids, so they are building blocks for other biomolecules, not proteins.

Proteins are polymers built from amino acids. The sequence and linkage of amino acids via peptide bonds form a polypeptide chain that folds into functional proteins. Each amino acid has an amino group, a carboxyl group, a central carbon, a hydrogen, and a side chain (R group) that imparts unique properties. During translation, the ribosome assembles amino acids in the order specified by mRNA, delivering them through tRNA so that the carboxyl group of one amino acid bonds to the amino group of the next, creating the growing chain with a free N-terminus and C-terminus. The variety of side chains among amino acids drives the structure and function of proteins.

Nucleotides form nucleic acids (DNA and RNA), monosaccharides form carbohydrates, and fatty acids form lipids, so they are building blocks for other biomolecules, not proteins.