The branch of the U.S. government that is composed of the president and all the individuals, agencies, and departments that report to the president, and that is responsible for administering and enforcing the laws that Congress passes.
Proteins are biological polymers composed of amino acids. Amino acids, linked together by peptide bonds, form a polypeptide chain. One or more polypeptide chains twisted into a 3-D shape form a protein. Proteins have complex shapes that include various folds, loops, and curves.
The unique sequence of amino acids that makes up a protein is called the protein's primary structure. Amino acids connect with one another through chemical bonds at the molecular level. Each amino acid has a general formula attached to a side chain. Amino acids differ from one another based on the type of side chain they possess.