What are amino acids?
Amino acids are the building blocks of proteins and play an essential role in metabolism.
Humans can produce 10 of the 20 amino acids. The others must be supplied in the food. Failure to obtain enough of even 1 of the 10 essential amino acids, those that we cannot make, results in degradation of the body's proteins—muscle and so forth—to obtain the one amino acid that is needed. Unlike fat and starch, the human body does not store excess amino acids for later use—the amino acids must be in the food every day.
What are proteins?
Proteins are macromolecules. They are constructed from one or more unbranched chains of amino acids. A typical protein contains 200–300 amino acids but some are much smaller and some much larger.
Every function in the living cell depends on proteins therefore they also depend on amino acids.
•Motion and locomotion of cells and organisms depends on proteins. [Examples: Muscles, Cilia and Flagella]
•All biochemical reactions are done by enzymes, which contain protein.
•The structure of cells, and the extracellular matrix in which they are embedded, is largely made of protein. [Examples: Collagens] (Plants and many microbes depend more on carbohydrates, e.g., cellulose, for support, but these are synthesized by enzymes.)
•The transport of materials in body fluids depends of proteins. [See Blood]
•The receptors for hormones and other signaling molecules are proteins.
•Proteins are an essential nutrient for heterotrophs.
•The transcription factors that turn genes on and off to guide the differentiation of the cell and its later responsiveness to signals reaching it are proteins.
• and many more — proteins are truly the physical basis of life.