Final answer:
Proteins are diverse in structure and function, and each cell contains numerous proteins with unique roles. They can be structural, regulatory, contractile, or protective, and serve in various processes such as transport, storage, or membranes. Proteins are polymers of amino acids arranged in a linear sequence.
Step-by-step explanation:
Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. They may be structural, regulatory, contractile, or protective; they may serve in transport, storage, or membranes; or they may be toxins or enzymes. Each cell in a living system may contain thousands of proteins, each with a unique function. Their structures, like their functions, vary greatly. They are all, however, polymers of amino acids, arranged in a linear sequence.