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.
Peptide subunits may bond with other peptides to form more complex structures. Multiple types of chemical bonds hold proteins together and bind them to other molecules. Here is a look at the chemical bonds responsible for protein structure. Primary Structure (Peptide Bonds) The primary structure of a protein consists of amino acids chained to each other. Amino acids are joined by peptide bonds. A peptide bond is a type of covalent bond between the carboxyl group of one amino acid and the amino group of another amino acid. Amino acids themselves are made of atoms joined together by covalent bonds.