What are the building blocks of proteins?

Proteins are made up of long chains of amino acids, which serve as their fundamental building blocks. Each amino acid consists of an amino group, a carboxyl group, a hydrogen atom, and a unique side chain (or R group) that determines the characteristics of that amino acid. There are 20 different amino acids that combine in various sequences to form proteins, which are essential for numerous biological functions, including catalyzing metabolic reactions, supporting immune responses, and providing structural support to cells and tissues.

Nucleotides, the components of nucleic acids like DNA and RNA, play a different role in coding and storing genetic information. Fatty acids are primarily involved in the formation of lipids, important for cell membranes and energy storage. Carbohydrates are used mainly for energy and structural purposes in cells, but they do not serve as the building blocks for proteins. Thus, amino acids are the correct answer when identifying the building blocks of proteins.