(a) Essential amino acids
(b) Peptide bond
(c) Denaturation
Ans.
(a) Essential amino acids: Essential amino acids are amino acids that cannot be synthesized by the human body and must be obtained from the diet. These amino acids are essential for the synthesis of proteins and the proper functioning of various physiological processes. There are nine essential amino acids for humans: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. These amino acids play crucial roles in protein synthesis, enzyme function, neurotransmitter synthesis, and other biochemical processes. A deficiency in essential amino acids can lead to impaired growth, muscle wasting, immune dysfunction, and other health problems.
(b) Peptide bond: A peptide bond is a covalent bond that forms between the amino group (-NH2) of one amino acid and the carboxyl group (-COOH) of another amino acid during protein synthesis. The formation of a peptide bond involves a condensation reaction, where a molecule of water is eliminated. The resulting bond forms between the carbon atom of the carboxyl group of one amino acid and the nitrogen atom of the amino group of another amino acid, creating a peptide bond (-CO-NH-). Peptide bonds link amino acids together to form polypeptide chains, which are the building blocks of proteins. The sequence and arrangement of amino acids in a polypeptide chain determine the structure and function of the protein.
(c) Denaturation: Denaturation is the process by which a protein loses its native structure and biological activity due to external stressors such as heat, pH changes, organic solvents, or mechanical agitation. Denaturation disrupts the weak non-covalent bonds and forces that maintain the three-dimensional structure of a protein, including hydrogen bonds, hydrophobic interactions, and disulfide bonds. As a result, the protein unfolds and loses its specific shape, leading to the loss of its biological function. While denaturation typically renders a protein inactive, it does not break peptide bonds, so the primary structure of the protein remains intact. Denatured proteins may or may not be able to regain their native structure and function once the denaturing conditions are removed, depending on the extent of the damage to the protein’s structure. Denaturation is reversible in some cases, but irreversible denaturation can lead to permanent loss of protein function.
