Final answer:
Proteins are essential macromolecules made up of amino acids that perform diverse functions in living organisms, including structural support, catalysis of metabolic reactions as enzymes, transport, and immune defense. Option a.
Step-by-step explanation:
Proteins are large, complex molecules that play many critical roles in living organisms. They are required for the structure, function, and regulation of the body's tissues and organs.
Proteins are made up of smaller units called amino acids, which are linked together in long chains. There are 20 different types of amino acids that can be combined to make a protein. The sequence of amino acids determines each protein’s unique 3-dimensional structure and function.
Proteins can be structural, protective, regulatory, contractile, or part of the body's transportation system.
They serve as enzymes to catalyze metabolic reactions, as antibodies to provide immune defense, and as signaling molecules to communicate between cells. Enzymes, a subclass of proteins, speed up chemical reactions within the body.
The various functions of proteins are influenced by their level of structure—primary, secondary, tertiary, and quaternary. Changes in temperature or pH can lead to protein denaturation and loss of function due to changes in protein shape.
Optio a.