Biomolecules — Revision Notes

⚡ 30-Second Revision

Carbohydrates — $(CH_2O)_n$. Monosaccharides (Glucose, Fructose), Disaccharides (Sucrose, Lactose), Polysaccharides (Starch, Glycogen, Cellulose, Chitin). Linkage: Glycosidic bond.
Proteins — Polymers of amino acids. 20 types. Linkage: Peptide bond. Structures: Primary (sequence), Secondary ($alpha$-helix, $\beta$-sheet), Tertiary (3D fold), Quaternary (multiple subunits). Denaturation: Loss of 3D structure, function.
Lipids — Hydrophobic. Fats/Oils (Triglycerides: Glycerol + 3 Fatty Acids), Phospholipids (Membrane), Steroids (Cholesterol, Hormones).
Nucleic Acids — DNA, RNA. Monomers: Nucleotides (Base + Sugar + Phosphate). Bases: A, G, C, T (DNA); A, G, C, U (RNA). Sugars: Deoxyribose (DNA), Ribose (RNA). Linkage: Phosphodiester bond.
Enzymes — Biocatalysts (mostly proteins). Lower activation energy. Specificity. Affected by Temp, pH, Substrate conc., Inhibitors. Cofactors: Prosthetic groups, Coenzymes, Metal ions.
Secondary Metabolites — Not directly involved in growth. E.g., Alkaloids, Terpenoids, Toxins, Lectins, Drugs, Pigments.

2-Minute Revision

Biomolecules are the organic compounds forming living organisms, categorized into carbohydrates, proteins, lipids, and nucleic acids. Carbohydrates are energy sources and structural components, ranging from simple monosaccharides (glucose) to complex polysaccharides (starch, cellulose) linked by glycosidic bonds.

Proteins, built from amino acids via peptide bonds, are highly versatile, serving as enzymes, structural elements, and transporters; their function depends on their specific 3D structure (primary, secondary, tertiary, quaternary).

Lipids are hydrophobic molecules for energy storage, membrane formation (phospholipids), and signaling (steroids). Nucleic acids (DNA, RNA) store and transmit genetic information, composed of nucleotides linked by phosphodiester bonds.

Enzymes, mostly proteins, are crucial biocatalysts that lower activation energy, and their activity is sensitive to temperature, pH, and substrate concentration. Remember to differentiate between primary metabolites (essential for life) and secondary metabolites (ecological roles, e.

g., toxins, alkaloids).

5-Minute Revision

Start by recalling the four major classes of biomolecules: carbohydrates, proteins, lipids, and nucleic acids. For carbohydrates, remember their general formula $(CH_2O)_n$ and classify them into monosaccharides (glucose, fructose), disaccharides (sucrose, lactose), and polysaccharides (starch, glycogen, cellulose, chitin).

Focus on the $alpha-1,4$ vs. $\beta-1,4$ glycosidic linkages and their functional implications (e.g., digestibility). For proteins, understand they are polymers of 20 types of amino acids, linked by peptide bonds.

Crucially, visualize the four levels of protein structure: primary (linear sequence), secondary ($alpha$-helix, $\beta$-sheet via H-bonds), tertiary (overall 3D fold via R-group interactions like disulfide, ionic, H-bonds, hydrophobic), and quaternary (multiple subunits).

Understand denaturation as the loss of higher-order structures and function. Lipids are diverse and hydrophobic; key types include triglycerides (glycerol + 3 fatty acids for energy storage), phospholipids (cell membranes), and steroids (cholesterol, hormones).

Note that lipids are not true polymers. Nucleic acids (DNA, RNA) are polymers of nucleotides, each comprising a nitrogenous base (A, G, C, T/U), a pentose sugar (deoxyribose/ribose), and a phosphate group.

Remember the differences between DNA and RNA in sugar, bases, and structure (double vs. single strand). Phosphodiester bonds link nucleotides. Finally, enzymes are mostly protein biocatalysts that lower activation energy, speeding up reactions without being consumed.

Recall factors affecting their activity (Temp, pH, substrate concentration) and the role of cofactors (prosthetic groups, coenzymes, metal ions). Don't forget secondary metabolites (e.g., morphine, ricin) and their ecological significance.

Prelims Revision Notes

1
Biomolecules — Organic compounds in living organisms. Primarily C, H, O, N, P, S.
2
Elemental Analysis — Living tissue contains C, H, O, N, etc. Acid-soluble pool (micromolecules <1000 Da: amino acids, monosaccharides, nucleotides, some lipids). Acid-insoluble pool (macromolecules >1000 Da: proteins, polysaccharides, nucleic acids, lipids).
3
Carbohydrates — Polyhydroxy aldehydes/ketones. Energy source, structural.

* Monosaccharides: Glucose, Fructose, Galactose (Hexoses); Ribose, Deoxyribose (Pentoses). * Disaccharides: Sucrose (Glucose+Fructose), Lactose (Glucose+Galactose), Maltose (Glucose+Glucose).

Linkage: Glycosidic bond. * Polysaccharides: Starch (plant energy, $alpha$-glucose, amylose/amylopectin), Glycogen (animal energy, highly branched $alpha$-glucose), Cellulose (plant structure, $\beta$-glucose), Chitin (fungal cell walls, arthropod exoskeleton, N-acetylglucosamine).

Homopolysaccharides (one monomer type), Heteropolysaccharides (multiple monomer types).

1
Proteins — Polymers of amino acids. Most abundant organic molecule.

* Amino Acids: Central C, $-NH_2$, $-COOH$, $-H$, $-R$ group. 20 types. Essential (dietary), Non-essential (synthesized). * Peptide Bond: $-COOH$ of one AA + $-NH_2$ of another AA, with $H_2O$ removal.

* Protein Structure: * Primary: Linear sequence of AAs. * Secondary: Local folding ($alpha$-helix, $\beta$-sheet) via H-bonds. * Tertiary: Overall 3D fold via R-group interactions (H-bonds, ionic, hydrophobic, disulfide bonds).

* Quaternary: Arrangement of multiple subunits. * Denaturation: Loss of 3D structure and function (primary structure intact).

1
Lipids — Water-insoluble. Energy storage, membranes, hormones.

* Triglycerides: Glycerol + 3 Fatty Acids (saturated/unsaturated). * Phospholipids: Glycerol + 2 Fatty Acids + Phosphate (cell membranes). * Steroids: Four-ring structure (Cholesterol, hormones).

1
Nucleic Acids — DNA, RNA. Genetic information.

* Nucleotide: Base + Sugar + Phosphate. * Nucleoside: Base + Sugar. * Bases: Purines (A, G), Pyrimidines (C, T/U). * Sugars: Deoxyribose (DNA), Ribose (RNA). * DNA: Double helix, A-T, G-C. RNA: Single strand, A-U, G-C. * Phosphodiester Bond: Links nucleotides.

1
Enzymes — Biocatalysts (mostly proteins, some ribozymes). Lower activation energy.

* Active Site: Substrate binding region. * Specificity: Highly specific. * Factors: Optimal Temp, pH. Substrate concentration (saturation). Inhibitors (competitive, non-competitive). * Cofactors: Non-protein part. Prosthetic groups (tightly bound), Coenzymes (loosely bound, vitamins), Metal ions. * Holoenzyme: Apoenzyme (protein) + Cofactor.

1
Secondary Metabolites — Not directly essential for growth. Ecological roles. E.g., Alkaloids (Morphine, Codeine), Terpenoids, Toxins (Ricin, Abrin), Lectins (Concanavalin A), Drugs (Vinblastin, Curcumin), Pigments, Gums, Rubber.

Vyyuha Quick Recall

Can People Like Nice Elephants? Sure! (For Classes: Carbohydrates, Proteins, Lipids, Nucleic Acids, Enzymes, Secondary Metabolites)