Which of the following proteins primarily serve structural roles?

Fibrous proteins primarily serve structural roles due to their elongated and fibrous shape, which allows them to form strong, stable structures. These proteins are often found in connective tissues, such as collagen in tendons and ligaments, and keratin in hair and nails. Their repetitive amino acid sequences and the way they aggregate enable them to provide support and strength to various biological structures.

In contrast, globular proteins are generally more rounded and are involved in a variety of functions, such as catalysis (enzymatic proteins) or transport, rather than serving a predominant structural purpose. Enzymatic proteins facilitate biochemical reactions and are critical for metabolic processes, while transport proteins are responsible for moving substances across cell membranes or throughout the organism, highlighting their functional role rather than a structural one. Fibrous proteins stand out for their unique contributions to the integrity and support of tissues.