A peptide bond is found primarily in which macromolecule?

The peptide bond is a specific type of covalent bond that links amino acids together to form proteins. This bond is formed through a dehydration synthesis reaction, where the carboxyl group of one amino acid reacts with the amino group of another, releasing a water molecule in the process. The resulting structure, a polypeptide, can fold into a functional protein, which performs a wide variety of roles in biological systems, including acting as enzymes, hormones, and structural components of cells.

In the context of the other macromolecules, fats (lipids) are primarily composed of glycerol and fatty acids, and they do not have peptide bonds. Carbohydrates consist of sugar molecules linked by glycosidic bonds, which are different from peptide bonds. Nucleic acids, such as DNA and RNA, are made up of nucleotide monomers connected by phosphodiester bonds, also distinct from peptide bonds. Therefore, the presence of peptide bonds is a defining characteristic of proteins, making them the correct answer in this context.