Classify amino acids. Add a note on their chemical properties.

1. 1 · Open in two lines. Amino acids are organic compounds with an amino group and a carboxyl group on the same (alpha) carbon. Twenty of them build all body proteins.
2. 2 · Draw the general structure. [Diagram: alpha carbon with –NH₂, –COOH, H and R side chain; beside it, the zwitterion form]
3. 3 · Classify on three bases.
   • By side chain: non-polar, polar uncharged, basic (positive), acidic (negative).
   • By nutrition: essential, semi-essential, non-essential.
   • By metabolic fate: glucogenic, ketogenic, both.
4. 4 · Chemical properties.
   • Amino group: ninhydrin (purple), acylation, Sanger's reagent, nitrous acid, transamination, deamination.
   • Carboxyl group: salts and esters, decarboxylation to amines, amide formation (asparagine, glutamine).
   • Both groups: zwitterion, isoelectric point, peptide bond.
5. 5 · Significance. Amino acids build proteins and also give rise to hormones, brain chemicals, purines and glucose.
6. 6 · Nutrition link. Cereals lack lysine, pulses lack methionine; cereal–pulse dishes like idli and khichdi improve protein quality.
7. 7 · Close in one line. End by linking amino acid make-up to protein quality in the Indian diet.

Scoring tip: Tables score fast here. Three neat classification tables and two short reaction lists cover most of the marks.