Protein molecules are constructed from which of the following?

Protein molecules are constructed from amino acids, which are organic compounds that serve as the building blocks of proteins. Each protein is made up of one or more long chains of amino acids, which are linked together through peptide bonds in a specific sequence. This sequence of amino acids determines the protein's structure and function, as the unique order of the amino acids influences how the protein folds into its final three-dimensional shape.

Amino acids contain an amino group, a carboxyl group, and a distinctive side chain (R group) that gives each amino acid its specific properties. There are 20 different amino acids that can be combined in various ways to create a vast array of proteins, each serving critical roles in biological processes, such as catalysis, transport, structural support, and signaling.

Fatty acids, nucleotides, and simple sugars are important biological molecules, but they serve different functions. Fatty acids are components of lipids, nucleotides are the building blocks of nucleic acids (like DNA and RNA), and simple sugars (monosaccharides) are the primary energy sources for cells, forming carbohydrates. Thus, the construction of proteins specifically from amino acids is key to understanding their biochemical roles and characteristics.