What is the primary biological function of proteins?

Proteins play a multitude of critical roles in biological systems, but their primary functions can be broadly categorized into two significant areas: serving as structural components and facilitating chemical reactions.

As structural components, proteins are essential for building and maintaining the architecture of cells and tissues. They are key in forming structures like muscles, skin, and hair, as well as providing support and shape to cells. For example, collagen is a protein that forms the connective tissues in the body, while keratin is found in hair and nails.

Proteins also play a vital role as enzymes, which are catalysts that speed up biochemical reactions in the body. They lower the activation energy required for reactions, thereby increasing the rate at which these reactions occur without being consumed in the process. This function is crucial for various metabolic processes, including digestion and energy production.

Thus, the correct answer encompasses both the structural role of proteins and their catalytic role in facilitating chemical reactions, highlighting the versatility and importance of proteins in sustaining life.