Kaplan Nursing Entrance Practice Exam 2026 – The All-in-One Guide to Exam Success!

Proteins are complex macromolecules essential for numerous biological functions, and their primary building blocks are amino acids. These organic compounds contain both an amino group and a carboxyl group, alongside a distinctive side chain specific to each amino acid. The unique sequence and arrangement of amino acids determine the protein's structure, which directly influences its functionality within the body.

This specificity is crucial for proteins' roles, such as enzymes that catalyze biochemical reactions, structural components in cells and tissues, transport molecules, immune responses, and signaling pathways. The diversity of protein function arises from the 20 standard amino acids that can be combined in various sequences, allowing for an immense variety of proteins with distinct properties and capabilities.

The other choices, while important biomolecules, do not contribute to the structural composition of proteins. Fatty acids are the building blocks of lipids, nucleotides are the units of nucleic acids like DNA and RNA, and monosaccharides are the simple sugars that make up carbohydrates. Each of these components plays different roles in biological systems, but they do not comprise proteins.