Organic ChemistryHigh Yield (2 Qs in JEE)

Biomolecules & Polymers Formulas

Carbohydrates (glucose, fructose, mutarotation), amino acids, peptide bonds, isoelectric point, and nucleic acids (DNA/RNA).

8 Formulas•572+ Questions in Bank

Core Formulas & Mathematical Identities

\text{H}_3\text{N}^+-\text{CH(R)}-\text{COO}^-, \quad \text{pI} = \frac{\text{p}K_{a1} + \text{p}K_{a2}}{2}

Dipolar ion with zero net charge at its characteristic isoelectric point pI.

Examiner Tip: At pH = pI, amino acid does not migrate under an applied electric field.

\text{Maltose: } \alpha\text{-D-Glc } (1\to 4) \text{ Glc}, \quad \text{Sucrose: } \alpha\text{-D-Glc } (1\to 2) \beta\text{-D-Fru} \; (\text{Non-reducing})

Glycosidic linkages in disaccharides.

Examiner Tip: Sucrose is non-reducing because both anomeric carbons are locked in the glycosidic bond.

A = T \; (2 \text{ H-bonds}), \quad G \equiv C \; (3 \text{ H-bonds}) \; (\text{In RNA: } A = U)

Watson-Crick base pairing in double-helix nucleic acids.

Examiner Tip: G-C base pairs have 3 hydrogen bonds and require higher thermal melting temperature (Tm) than A-T pairs.

\alpha\text{-D-Glucopyranose } (+112^\circ) \xrightleftharpoons[36\%]{64\%} \text{Open Chain} \xrightleftharpoons{} \beta\text{-D-Glucopyranose } (+19^\circ) \implies [\alpha]_D = +52.7^\circ

Spontaneous change in specific optical rotation until an equilibrium mixture of α and β anomers is reached in aqueous solution.

Examiner Tip: β-anomer is more stable (64%) because all bulky -OH groups and -CH₂OH occupy equatorial positions in chair conformation.

\text{Sucrose } (+66.5^\circ) + \text{H}_2\text{O} \xrightarrow{\text{invertase}} \text{D-(+)-Glucose } (+52.7^\circ) + \text{D-(-)-Fructose } (-92.4^\circ) \implies [\alpha]_{\text{mix}} = -19.8^\circ

Hydrolysis converts dextrorotatory sucrose into a levorotatory equimolar mixture called invert sugar due to stronger levorotation of D-(-)-fructose.

Examiner Tip: Follows pseudo-first order kinetics.

-\text{C}(=\text{O})-\text{NH}- \longleftrightarrow -\text{C}(\text{O}^-)=\text{N}^+\text{H}- \quad (\text{Partial double bond character})

Resonance restricts free rotation around C-N bond, causing the six atoms of the peptide unit (C_α, C, O, N, H, C_α) to be coplanar.

Examiner Tip: Trans-conformation is favored over cis-conformation to minimize steric hindrance between side chains.

\text{Monosaccharide} + 3 \text{ Ph-NH-NH}_2 \longrightarrow \text{Osazone} + \text{Ph-NH}_2 + \text{NH}_3 + 2\text{H}_2\text{O}

Reaction with excess phenylhydrazine. D-glucose, D-mannose, and D-fructose yield the EXACT same osazone crystal.

Examiner Tip: Confirms that D-glucose and D-fructose differ configurationally only at C-1 and C-2.

\text{Fat-Soluble: } A, D, E, K; \quad \text{Water-Soluble: } B\text{-complex, } C; \quad \text{B}_{12} \implies \text{Pernicious Anemia (contains Co)}

Classification by solubility. Water-soluble vitamins must be supplied regularly in diet as they are excreted in urine (except B₁₂).

Examiner Tip: Vitamin C (ascorbic acid) cannot withstand heat and is easily destroyed during cooking.

Frequently tested misconceptions in Biomolecules & Polymers

•Glucose gives negative 2,4-DNP and Schiff's tests because the aldehyde group forms a cyclic hemiacetal ring.
•All natural amino acids (except glycine) are chiral and possess L-configuration.