Explain how fibrous proteins differ from globular proteins in terms of their structure and function.

Fibrous proteins have a repetitive, elongated polypeptide chain, usually consisting of long alpha‑helices or beta‑sheets arranged along an axis, giving them a rod‑like shape. In contrast, globular proteins fold into a compact, roughly spherical tertiary structure.

Because of their extended structure, fibrous proteins are largely insoluble in water, whereas globular proteins are generally water‑soluble due to hydrophilic side chains exposed on their surface.

Fibrous proteins function mainly as structural or mechanical components – for example, collagen provides tensile strength in connective tissue and keratin gives hardness to hair and nails.

Globular proteins perform dynamic metabolic roles such as catalysis (enzymes), transport (haemoglobin) or signalling (hormones, receptors), enabled by specific active or binding sites formed by their tertiary folding.