What are the building blocks of proteins?

The correct answer is amino acids because they are the fundamental units that combine to form proteins. Proteins are made through a process called translation, during which sequences of amino acids are linked together by peptide bonds to create polypeptides. Each protein has a specific sequence and number of amino acids that determine its unique structure and function in biological systems.

Amino acids contain both an amine group and a carboxyl group, along with a side chain, which varies among different amino acids and influences the properties of the resulting protein. There are 20 standard amino acids that serve as the building blocks for all proteins, allowing for a vast diversity of protein structures and functions essential for life.

The other options refer to different biological molecules: monosaccharides are the building blocks of carbohydrates, nucleotides are the building blocks of nucleic acids like DNA and RNA, and fatty acids are components of lipids. Each plays distinct roles in biological processes but does not contribute directly to protein synthesis.