Question

Define the following:
(i) Peptide linkage
(ii) Denatured protein

Answer 1

(i) Peptide linkage: The covalent bond uniting two amino acids, formed when the carboxyl group of one reacts with the amino group of another, liberating water. This linkage constitutes the protein's structural foundation.
(ii) Denatured protein: A protein whose native three-dimensional conformation has been disrupted by external agents such as elevated temperature, pH variations, or chemical substances. While this process compromises the protein's functional activity, its primary sequence of amino acids remains unchanged.

Answer 2

Amino acids exhibit amphoteric properties due to the presence of both acidic and basic functional groups. The carboxyl group (-COOH) acts as an acid by releasing a proton (H+) in solution, whereas the amino group (-NH2) functions as a base by accepting a proton. This inherent duality enables amino acids to function as both acids and bases, contingent upon the solution's pH.

Answer 3

Fibrous proteins, such as collagen and keratin, are elongated and water-insoluble, serving structural purposes and providing mechanical support. In contrast, globular proteins are spherical, water-soluble, and perform functional roles like enzymes and antibodies, participating in metabolic processes.

Answer 4

The two distinct secondary protein structures are:
\r1. Alpha helix: Characterized by a polypeptide chain forming a right-handed spiral, maintained by hydrogen bonds.
\r\r2. Beta-pleated sheet: Consists of polypeptide chains arranged in parallel or antiparallel fashion, stabilized by hydrogen bonds between adjacent segments.