Final answer:
Proteins can be classified into two major structural categories: fibrous proteins and globular proteins. Fibrous proteins are long polymer chains arranged parallel to one another, forming fibers or sheets. They are insoluble in water and have structural functions.
Step-by-step explanation:
Proteins can be classified into two major structural categories: fibrous proteins and globular proteins. Fibrous proteins are long polymer chains arranged parallel to one another, forming fibers or sheets. They are insoluble in water and have structural functions. Examples of fibrous proteins include keratins, collagens, myosins, and elastins. Keratin is found in hair and the outer layer of skin, collagen is present in connective tissues, myosins are muscle proteins, and elastins are found in ligaments and artery walls.