Master Memory Capsule — Biomolecules
A one-glance revision sheet for the morning of your Board, JEE or NEET paper.
Carbohydrates: polyhydroxy aldehydes/ketones. Mono (glucose = aldohexose, fructose = ketohexose) → di (sucrose, maltose, lactose) → poly (starch, glycogen, cellulose). Reducing sugars (all monosaccharides, maltose, lactose) reduce Fehling/Tollens; sucrose is non-reducing.
Glucose, Disaccharides & Polysaccharides
Glucose: aldohexose; in solution mostly the cyclic pyranose hemiacetal; C-1 = anomeric carbon → alpha/beta anomers; their interconversion = mutarotation. Fructose = ketohexose, furanose ring.
Glycosidic linkage joins sugars (loss of water). Sucrose (glucose+fructose, non-reducing; hydrolyses to invert sugar); maltose (glucose+glucose); lactose (glucose+galactose).
Polysaccharides: starch = amylose (linear, soluble) + amylopectin (branched), of alpha-glucose (plant store, blue-black with iodine); glycogen = branched alpha-glucose (animal store); cellulose = linear beta-glucose (structural, indigestible to humans).
Amino Acids, Proteins & Enzymes
Amino acids: alpha-amino acid (-NH and -COOH on same C); exist as the zwitterion ⁺HN-CHR-COO⁻; amphoteric; high-melting, water-soluble; isoelectric point = pH of the neutral zwitterion; essential (diet) vs non-essential (body-made).
Proteins: polymers of amino acids via peptide bonds (-CO-NH-). Structure levels: primary (sequence), secondary (alpha-helix / beta-pleated sheet, H-bonds), tertiary (3-D fold), quaternary (subunits). Denaturation destroys secondary/tertiary but keeps primary (e.g. boiled egg white). Fibrous (structural) vs globular (functional).
Enzymes: biological catalysts (globular proteins) that lower activation energy; highly specific (lock-and-key active site); have optimum temperature and pH.
Vitamins, Nucleic Acids & Last-Minute Triggers
Vitamins: fat-soluble A, D, E, K (stored, toxic in excess); water-soluble B & C (not stored). Deficiencies: A → night blindness; B → beriberi; B → pernicious anaemia; C → scurvy; D → rickets/osteomalacia; K → poor clotting.
Nucleic acids: polymers of nucleotides (sugar + base + phosphate); nucleoside = sugar + base (no phosphate). DNA = deoxyribose, bases A G C T, double helix; RNA = ribose, base U, single-stranded. Base pairing A-T (2 H-bonds), G-C (3 H-bonds). Functions: replication and protein synthesis (transcription → translation).
One-line recall: glucose pyranose/anomers/mutarotation; sucrose non-reducing → invert sugar; starch (alpha) vs cellulose (beta); amino-acid zwitterion & isoelectric point; protein primary→quaternary, denaturation keeps primary; enzymes = specific protein catalysts; vitamins A D E K fat-soluble (know the deficiency diseases); DNA (deoxyribose, A-T/G-C, double helix) vs RNA (ribose, U).