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.
Amino acids are chemical structures chained together to compose various types of proteins. Twenty-one amino acids (essential amino acids, and non-essential amino acids) are recognized in science to have some kind of useful function, ranging from providing energy for the body to protecting against cardiovascular disease.