Introduction to Biomolecules

Overview

This lecture explains important concepts of the Biomolecules chapter, their definitions, types, properties, and exam-relevant points in detail.

Identification and Importance of Biomolecules

• Biomolecules are all carbon-containing compounds found in living systems.
• Their average weightage is 5 questions every year in NEET (for 20 marks).
• Tissue analysis and ash analysis are essential to know the types of biomolecules.

Tissue and Ash Analysis

• Tissue analysis identifies organic (biomolecules); ash analysis identifies inorganic elements.
• Slurry made from tissue yields filtrate (monomers, micromolecules) and retentate (polymers, macromolecules).
• Lipids are an exception: despite their small size, they are found in the retentate.

Cell Composition

• Cells contain 70–90% water, 10–15% protein, 5–7% nucleic acid, 2–3% carbohydrate, and 1–2% lipids.
• Most abundant chemical: water; most abundant element: oxygen.

Types of Metabolites

• Primary metabolites: glucose, chlorophyll (essential for life processes).
• Secondary metabolites: alkaloids (morphine, codeine), drugs, toxins, lectins, pigments (special functions, defense).

Carbohydrates

• Definition: hydrates of carbon containing aldehyde or ketone groups.
• Types: monosaccharides (3–7C), oligosaccharides (2–10), polysaccharides (>10).
• Monosaccharides all give positive Fehling/Benedict tests; disaccharides (maltose, lactose), polysaccharides (starch, glycogen, cellulose, chitin).
• Starch: in plants, two components (amylose, amylopectin). Glycogen: animal storage, branched structure.
• Inulin: in tuber of Dahlia, used for renal function test.

Proteins and Amino Acids

• Amino acids contain amino and acidic groups; monomers of proteins.
• Twenty types of amino acids; essential ones must be obtained from diet.
• Protein structure: primary (linear; n–c terminal), secondary (α-helix, β-pleated; H-bond), tertiary (most stable, functional), quaternary.
• Functions: enzymes, hormones, immunoglobulins, transport (bloodborne), visual pigment.

Lipids

• Fat soluble, soluble in non-polar solvents.
• Neutral lipids (fatty acid + glycerol), phospholipids (part of plasma membrane; lecithin), cholesterol (fluidity/hormone synthesis).
• Fatty acids: saturated (single bond), unsaturated (double bond: MUFA, PUFA).

Enzymes

• Biocatalysts, mostly proteins (ribozyme exception).
• Active site; tertiary structure; holoenzyme = apoenzyme + cofactor.
• Classes: oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases.
• Properties: substrate specificity, turnover number, optimal temp/pH.
• Inhibition: competitive (Km↑, Vmax same), non-competitive (Vmax↓, Km same).
• Maximum affinity = lowest Km.

Key Terms & Definitions

• Biomolecule — carbon-containing compound present within living organisms.
• Mono/di/polysaccharide — types of carbohydrates; respectively 1, 2–10, 10+ units.
• Analysis — information on organic/inorganic by tissue and ash.
• Enzyme — a biological catalyst.
• Holoenzyme — combined unit of apoenzyme + cofactor.

Action Items / Next Steps

• Read the NCERT Biomolecules chapter carefully.

• Solve extra question sets and practice sets.

• Prepare structures of proteins, lipids, enzymes for the next class.Here's a neatly formatted text version of the mind map you can use to create a visual mind map in any tool:

  Biomolecules ├── 1. Definition & Importance │ ├── Carbon-containing compounds in living systems │ ├── NEET weightage: ~5 questions/year (20 marks) │ └── Tissue & Ash analysis for identification ├── 2. Tissue & Ash Analysis │ ├── Tissue analysis: organic biomolecules │ ├── Ash analysis: inorganic elements │ ├── Slurry → Filtrate (monomers, micromolecules) │ ├── Retentate (polymers, macromolecules) │ └── Lipids: exception, found in retentate ├── 3. Cell Composition │ ├── Water: 70–90% │ ├── Protein: 10–15% │ ├── Nucleic acid: 5–7% │ ├── Carbohydrates: 2–3% │ ├── Lipids: 1–2% │ ├── Most abundant chemical: Water │ └── Most abundant element: Oxygen ├── 4. Metabolites │ ├── Primary: glucose, chlorophyll (essential) │ └── Secondary: alkaloids, drugs, toxins, pigments, lectins ├── 5. Carbohydrates │ ├── Definition: hydrates of carbon with aldehyde/ketone groups │ ├── Types: │ │ ├── Monosaccharides (3–7C) │ │ ├── Oligosaccharides (2–10 units) │ │ └── Polysaccharides (>10 units) │ ├── Tests: monosaccharides positive for Fehling/Benedict │ ├── Examples: │ │ ├── Maltose (2 glucose units) │ │ ├── Lactose (glucose + galactose) │ │ ├── Sucrose (glucose + fructose, non-reducing) │ │ ├── Starch (amylose & amylopectin) │ │ ├── Glycogen (animal starch) │ │ ├── Cellulose (β-1,4 linked glucose) │ │ ├── Chitin │ │ └── Inulin (renal function test) ├── 6. Proteins & Amino Acids │ ├── Amino acids: amino & acidic groups; 20 types; essential from diet │ ├── Protein structure: │ │ ├── Primary: linear, peptide bonds │ │ ├── Secondary: α-helix & β-pleated sheets (H-bonds) │ │ ├── Tertiary: 3D folding, stable │ │ └── Quaternary: multiple chains │ └── Functions: enzymes, hormones, antibodies, transport, visual pigments ├── 7. Lipids │ ├── Fat soluble; soluble in non-polar solvents │ ├── Types: │ │ ├── Neutral lipids (fatty acid + glycerol) │ │ ├── Phospholipids (plasma membrane) │ │ └── Cholesterol (membrane fluidity, steroid hormones) │ └── Fatty acids: │ ├── Saturated (single bonds) │ └── Unsaturated (double bonds: MUFA, PUFA) └── 8. Enzymes ├── Biological catalysts, mostly proteins (exception: ribozymes) ├── Structure: active site, tertiary structure, holoenzyme = apoenzyme + cofactor ├── Classes: oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases ├── Properties: substrate specificity, turnover number, optimum temp & pH ├── Inhibition: │ ├── Competitive (Km ↑, Vmax unchanged) │ └── Non-competitive (Vmax ↓, Km unchanged) └── Km: inverse measure of enzyme affinity for substrate

  You can paste this into mind mapping software like MindMeister, XMind, or draw it on paper for a clear visual overview.

  If you want, I can also help you with step-by-step instructions to create this in a specific tool. Would you like that?