Proteins are polymers of twenty-two standard alpha-amino acids that are joined by peptide bonds.
<u>Structure of amino acid</u>-It is made up of compounds containing carbon, nitrogen, oxygen, and hydrogen. In an amino acid, the positively charged amino group and the negatively charged carboxyl group are attached to the same carbon atom (alpha carbon). The 22 amino acids differ from one another because of the side chain attached to the central carbon atom. The central carbon atom is also attached to the H atom.
<u>Proteins have four levels of structural organization</u><u>- </u>
- Primary structure
- Secondary structure
- Tertiary structure
- Quaternary structure
Quaternary structure-It is made up of two or more polypeptide chains. Each polypeptide chain is called a subunit. The polypeptide chains in the quaternary structure of a protein can be similar or different. The polypeptides are stabilized by noncovalent bonds such as hydrophobic interactions, hydrogen bonds, and electrostatic interactions. For example-Hemoglobin.
The answers for the blanks are-
1.Noncovalent, 2.amino, 3.carboxyl, 4. quaternary structure
For more information on four levels of the structural organization-
