Apex Class Logo
APEX CLASS ESTD 2018

IITJEE CHEMISTRY: Biomolecules, Amino Acids & Polymers Visualizer

By

Ashish Kumar Bahekar

Published on

in

APEX CLASS • IITJEE Organic Chemistry Lab

Biomolecules, Amino Acids & Polymers

Master Glucose Anomers, Zwitterion Isoelectric Points (pI), DNA/RNA Differences, and Polymer Types!

🔬 Select a Biomolecule Concept to Visualize:
D-Glucose (Fischer) CHO H OH HO H H OH H OH CH₂OH Hemiacetal Form → α-D-Glucopyranose O OH (Down = α) C1 OH OH OH O OH (α-Down) H C1 (Anomeric) Anomers & Mutarotation • C1 is the Anomeric Carbon. • α-isomer: -OH is DOWN. • β-isomer: -OH is UP. Mutarotation: In water, pure α (112°) or pure β (+19°) equilibrate to +52.7°! Disaccharides & Glycosidic Linkages (The Water Dropping Mechanism) Maltose (α-D-Glu + α-D-Glu) O α-1,4-Glycosidic Linkage Free Hemiacetal (Reducing!) Sucrose (α-D-Glu + β-D-Fru) O α,β-1,2-Glycosidic Linkage NO Free Hemiacetal (Non-Reducing!) Inverted Sugar: Hydrolysis of Sucrose (Dextro, +66.5°) yields Glucose (+52.5°) and Fructose (-92.4°). The net mixture becomes LAEVOROTATORY (-), hence “Inversion”! 1. Reducing Sugars (Maltose, Lactose) Contain a FREE Hemiacetal (C-OH) at C1. R-O-CH(OH)-R’ Aq. Solution R-CHO • Reduces Tollens’ Reagent (Silver Mirror) • Reduces Fehling’s Solution (Red Ppt) • Show Mutarotation! 2. Non-Reducing Sugars (Sucrose) Both anomeric carbons are locked in an Acetal! R-O-CH(OR)-R’ Aq. Solution NO Aldehyde! • Fails Tollens’ & Fehling’s Tests. • Does NOT show Mutarotation. • Does NOT form Osazones. Nucleic Acids: Nucleotide Structure (DNA vs RNA) PO₄³⁻ Pentose Sugar 2′-Position N-Base Key Differences Sugar: RNA has OH at 2′ (Ribose) DNA has H at 2′ (Deoxyribose) Bases: DNA = A, G, C, Thymine RNA = A, G, C, Uracil Base Pairing (Hydrogen Bonds): Adenine = Thymine (2 H-bonds) | Guanine ≡ Cytosine (3 H-bonds)
Starch Components
Amylose & Amylopectin
Amylose is linear (1,4), Pectin is branched (1,6)
Cellulose Linkage
β-1,4-Glycosidic
Humans cannot digest beta linkages!
Vitamins (Water Soluble)
Vitamins B & C
Must be supplied regularly in diet.
Vitamins (Fat Soluble)
Vitamins A, D, E, K
Stored in liver and adipose tissues.
🧪 Select a Protein or Polymer Concept:
Amino Acids: Zwitterion Form & Isoelectric Point (pI) Low pH (Acidic) Isoelectric Point (pH = pI) High pH (Basic) H₃N⁺ – CH(R) – COOH Cationic Form Migrates to Cathode (-) ⇌ H₃N⁺ – CH(R) – COO⁻ Zwitterion (Dipolar Ion) Net Charge = 0 (No Migration) ⇌ H₂N – CH(R) – COO⁻ Anionic Form Migrates to Anode (+) At the Isoelectric Point (pI), amino acids are least soluble in water. All naturally occurring amino acids are L-Amino Acids (except Glycine, which is achiral)! Peptide Bond Formation: Condensation Reaction (-H₂O) H₂N – CH(R₁) – C=O OH + H NH – CH(R₂) – COOH – H₂O H₂N – CH(R₁) – C – N – CH(R₂) – COOH || O | H Peptide (Amide) Linkage Due to Resonance, the C-N bond has partial double bond character making it Rigid & Planar! Protein Structure Hierarchy & Denaturation 1°: Sequence (Peptide Bonds) → 2°: α-Helix / β-Sheet (Hydrogen Bonds) → 3°: 3D Folding (Disulfide, Ionic, VDW) → 4°: Multi-Subunit (e.g., Hemoglobin) 🚨 Denaturation (Heat/pH change): Destroys 2°, 3°, and 4° structures, but PRIMARY structure remains intact! Polymerization: Addition (Chain-Growth) vs Condensation (Step-Growth) 1. Addition Polymers (Alkenes) n CH₂=CH₂ -[ CH₂-CH₂ ]n – Polythene. No by-products lost. Uses Ziegler-Natta Catalyst (High Density) 2. Condensation Polymers Hexamethylenediamine + Adipic Acid – nH₂O Nylon-6,6 (A Polyamide) Forms by loss of small molecules (H₂O, HCl) Dacron (Terylene) is a Polyester (Ethylene glycol + Terephthalic acid)!
Essential Amino Acids
Valine, Leucine, Lysine
Cannot be synthesized by the body.
Globular vs Fibrous
Insulin vs Keratin
Globular are water soluble, Fibrous are not.
Vulcanization of Rubber
Heating with Sulfur (S)
Forms cross-links making it hard & non-sticky.
Biodegradable Polymer
PHBV & Nylon-2-nylon-6
Used in specialty packaging & medical implants.
🔥 High-Yield JEE Amino Acid Tricks:
1. Ninhydrin Test: General test for amino acids (yields a deep blue/purple color called Ruhemann’s purple).
2. Acidic vs Basic Amino Acids: Aspartic Acid & Glutamic Acid have extra -COOH groups (pI < 7). Lysine, Arginine, & Histidine have extra -NH₂ groups (pI > 7). Arginine is the most basic amino acid due to its Guanidino group!
, , ,

Read Next:

Leave a Reply

Apex Class App

Play revision games, read notes, and test your skills anywhere!

🚀

Fresh Updates

Latest notes, lectures & announcements!

View All Posts ➔
⚡

Interactive Zones

🎮
Study Games Arena Play & Revise Concepts
→ 🎯
Study Quiz Arena Test Your Knowledge
→ 🏛️
UPSC Quiz Arena Master Civil Services
→

Discover more from Apex Class

Subscribe now to keep reading and get access to the full archive.

Continue reading

Enable Notifications OK No thanks