A protein is best defined as?

A protein is best defined as a three-dimensional polymer made from amino acids. This definition highlights the essential components and structure of a protein. Proteins are made up of long chains of amino acids linked together by peptide bonds. The sequence of these amino acids, dictated by the organism's genetic code, determines the protein's unique structure and function.

The three-dimensional nature of proteins is critical; it's this specific folding and conformation that enables proteins to perform their biological roles, such as catalyzing metabolic reactions, facilitating movement, and serving as signaling molecules. The folding process is often influenced by various interactions among the amino acids and their environment, resulting in specific shapes that are crucial for protein functionality.

In contrast, a linear chain of nucleotides pertains to nucleic acids like DNA and RNA, and a complex carbohydrate structure refers to polysaccharides, which are made of sugar units rather than amino acids. Additionally, a collection of fatty acids describes lipids, which are fundamentally different from proteins both in structure and function. Understanding these distinctions helps clarify why the definition of proteins as three-dimensional polymers of amino acids is accurate and reflects their biological significance.