LIFE SCIENCE

Detailed explanation-1: -Each polypeptide chain in such a protein is called a protein subunit. In the simplest case, two identical folded polypeptide chains bind to each other in a “head-to-head” arrangement, forming a symmetric complex of two protein subunits (a dimer) held together by interactions between two identical binding sites.

Detailed explanation-2: -The subunits are held together by hydrogen bonds and van der Waals forces between nonpolar side chains. The subunits in a quaternary structure must be specifically arranged for the entire protein to function properly.

Detailed explanation-3: -Within a protein, multiple amino acids are linked together by peptide bonds, thereby forming a long chain. Peptide bonds are formed by a biochemical reaction that extracts a water molecule as it joins the amino group of one amino acid to the carboxyl group of a neighboring amino acid.

Detailed explanation-4: -A peptide bond is formed by a dehydration synthesis or reaction at a molecular level. This reaction is also known as a condensation reaction which usually occurs between amino acids. As depicted in the figure given below, two amino acids bond together to form a peptide bond by dehydration synthesis.

Detailed explanation-5: -A peptide bond forms when the amino group of one amino acid bonds to the carboxyl group of another amino acid. A peptide is two or more amino acids joined together by peptide bonds, and a polypeptide is a chain of many amino acids.