<prompt> Which amino acid is acidic?Aspartic acidValineLeucineAspartate  <response>: Ans. a Aspartic acidBased in variable side chain, amino acid can be classified into: Aliphatic amino acid and Aromatic amino acid.Aliphatic amino acidAromatic amino acidIt is further classified into several subtypes: Simple AA: Glycine, Alanine Branched chain AA: Leucine, Isoleucine, Valine Sulphur containing: Cysteine, Methionine With-OH group: Serine, Threonine With amide group: Asparagine, Glutamine Acidic AA: Aspartic acid, Glutamic acid Basic AA: Arginine, Lysine Histidine Tyrosine Tryptophan Phenylalanine Basic amino acid: Histidine, Arginine, Lysine Histidine is also basic in nature, but it is aromatic -OH containing AA: Threonine, Serine, Tyrosine Most basic amino acid: Arginine 