The macromolecule composed of chains of amino acids linked together by peptide bonds is called?

• A. Proteins
• B. Nucleic Acids
• C. Lipids
• D. Carbohydrates

Answer: (A)

Proteins are polymers built from amino acids linked by peptide bonds. A peptide bond forms when the amino group of one amino acid joins with the carboxyl group of the next amino acid, releasing a molecule of water in a dehydration synthesis reaction. This repeated linkage creates a polypeptide chain that can fold into a specific three-dimensional structure to carry out a vast array of functions, from enzymes and signaling molecules to structural components and transporters.

Nucleic acids, in contrast, are polymers of nucleotides connected by phosphodiester bonds along a sugar-phosphate backbone. Lipids are not joined in a uniform chain of repeating units like the others; they form diverse molecules such as fats, phospholipids, and steroids that aren’t built from amino acid linkages. Carbohydrates are polymers of monosaccharides joined by glycosidic bonds, again not peptide bonds.