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.
Protein Structure. Proteins are polymers of amino acids. The amino acids of a protein are linked by peptide bonds. Alpha helices and beta pleated sheets are characteristic of a protein's secondary structure. Electronegative oxygen and nitrogen atoms leave hydrogen atoms with partial positive charges. Peptide bonds link together the amino acids of a protein's primary structure.