AP BIOLOGY

Detailed explanation-1: -Quaternary structure is held together by noncovalent bonds between complementary surface hydrophobic and hydrophilic regions on the polypeptide subunits. Additionally, acidic and basic side chains can form salt linkages.

Detailed explanation-2: -Tertiary structure refers to the configuration of a protein subunit in three-dimensional space, while quaternary structure refers to the relationships of the four subunits of hemoglobin to each other.

Detailed explanation-3: -The quaternary structure of a protein is the association of several protein chains or subunits into a closely packed arrangement. Each of the subunits has its own primary, secondary, and tertiary structure. The subunits are held together by hydrogen bonds and van der Waals forces between nonpolar side chains.

Detailed explanation-4: -Quaternary structure However, some proteins are made up of multiple polypeptide chains, also known as subunits. When these subunits come together, they give the protein its quaternary structure.