Biomolecules Visual Guide — Structures, Reactions & Maps — Summary

Glucose Open-Chain Structure

SMILES: OC[C@@H](O)[C@H](O)[C@@H](O)[C@@H](O)C=O

Glucose is an aldohexose: six carbons, aldehyde at C1, four chiral centres (C2–C5).

Glycine (Simplest Amino Acid)

SMILES: NCC(=O)O

General amino acid at isoelectric point (zwitterion): SMILES: [NH3+]CC(=O)[O-]

Peptide Bond Formation (Text Reaction)

H2N-CHR1-COOH  +  H2N-CHR2-COOH
        ↓  condensation (-H2O)
H2N-CHR1-CO-NH-CHR2-COOH  (dipeptide)

Sucrose Glycosidic Bond (Why Non-Reducing)

Glucose (C1-OH) ──glycosidic bond── Fructose (C2-OH)
     ↑ anomeric C locked               ↑ anomeric C locked
     → no free aldehyde/ketone → NON-REDUCING

Sucrose SMILES: OC[C@H]1O[C@@](CO)(O1)[C@@H]1O[C@H](CO)[C@@H](O)[C@H](O)[C@H]1O

Carbohydrate Classification Map

Carbohydrates
├── Monosaccharides
│   ├── Aldoses: Glucose (aldohexose), Galactose (aldohexose), Ribose (aldopentose)
│   └── Ketoses: Fructose (ketohexose)
├── Disaccharides
│   ├── Sucrose (non-reducing) — α-1,2 linkage
│   ├── Lactose (reducing) — β-1,4 linkage
│   └── Maltose (reducing) — α-1,4 linkage
└── Polysaccharides
    ├── Starch: Amylose (α-1,4 linear) + Amylopectin (α-1,4/α-1,6 branched)
    ├── Cellulose: β-1,4 linear (indigestible)
    └── Glycogen: α-1,4/α-1,6 (most branched, animal storage)

DNA Base-Pairing Visual

5'— A — T — G — C — A — T —3'
    |   ||  |||  |   ||
3'— T — A — C — G — T — A —5'
    2   2   3   3   2   2   ← number of H-bonds

Formula: $n_{H\text{-bonds}} = 2 \times n_{AT} + 3 \times n_{GC}$

Protein Structure Levels (Hierarchical)

Primary   →  Peptide bonds (covalent sequence)
    ↓ folding
Secondary →  α-helix (intra H-bonds) / β-sheet (inter H-bonds)
    ↓ folding
Tertiary  →  3D fold: –S–S–, hydrophobic, ionic, H-bonds
    ↓ assembly
Quaternary → Multiple subunits (e.g., Haemoglobin: 4 subunits)

Denaturation arrow points backward from Quaternary → Secondary level (primary is never disrupted).

Apparatus Reference

Iodine-starch test apparatus (standard lab setup): https://commons.wikimedia.org/wiki/Special:FilePath/$Iodine_{test}$.jpg?width=600