Major Biomolecules

Reviewer on Major Biomolecules

1. Introduction to Biomolecules

  • Common elements in organisms: Carbon (C), Oxygen (O), Nitrogen (N), Phosphorus (P), Sulfur (S), Hydrogen (H).

  • Types of biomolecules: Carbohydrates, Lipids, Proteins, Nucleic Acids.

  • Functions: Fuel for metabolism, crucial for cellular activities, necessary for proper body functions.

2. Carbohydrates

  • Definition: Biomolecules, the most abundant organic compounds, majorly found in plants (e.g., cellulose).

  • Composition: Carbon-hydrogen-oxygen ratio of 1:2:1.

  • Main roles: Energy source, brain function, muscle activity.

3. Types and Functions of Carbohydrates
A. Monosaccharides

  • Simple sugars: Smallest carbohydrate units, immediate energy source.

  • Types:

    • Aldoses (contain aldehyde group, -CHO)

    • Ketoses (contain ketone group, C=O).

  • Examples:

    • Glucose: Major energy source, found in all organisms.

    • Fructose: Found in plants like sugarcane and corn.

    • Derivatives: Ascorbic acid (Vitamin C), sorbitol, mannitol.

B. Disaccharides

  • Definition: Two monosaccharides joined by condensation reaction, form glycosidic bond.

  • Examples:

    • Sucrose: Combination of glucose and fructose, used in sweeteners.

    • Lactose: Glucose + galactose, found in dairy.

    • Maltose: Two glucose molecules, found in beer production.

C. Polysaccharides

  • Definition: Composed of three or more monosaccharides, not sweet.

  • Examples:

    • Starch: Energy storage in plants.

    • Glycogen: Energy storage in animals.

    • Pectin: Soluble fiber, found in fruits like apples and oranges, used in making jams and jellies.

    • Cellulose: Structural polysaccharide, found in plant cell walls, used in fabrics and paper.

    • Chitin: Found in fungi and exoskeletons of animals, harder and more stable than cellulose.

4. Functions of Polysaccharides

  • Energy storage: Immediate reserves (e.g., glycogen, starch).

  • Health benefits: Stabilizes blood sugar, provides vitamins and fiber.

  • Structural role: Forms rigid structures in organisms (e.g., cellulose in plants, chitin in fungi and animals).

Lipids

Lipids are biomolecules made of hydrocarbon chains, insoluble in water, and release energy when metabolized. They serve as long-term energy storage and insulation, crucial for cold-adapted animals like polar bears and penguins.

Types of Lipids:

  1. Triglycerides: Comprised of glycerol and three fatty acids.

    • Saturated fats: Solid at room temperature, found in animal fats, associated with circulatory disorders.

    • Unsaturated fats: Liquid at room temperature, found in plant oils.

  2. Phospholipids: Contain a phosphate group, forming a bilayer in cell membranes with hydrophilic heads and hydrophobic tails.

  3. Steroids: Feature four fused carbon rings, including cholesterol, which regulates metabolism and immune response, and sex hormones like testosterone and estrogen.

  4. Waxes: Esters of long-chain fatty acids, hydrophobic, and provide waterproofing and protection in plants and animals.

Proteins

Proteins are essential biomolecules, comprising about 75% of an organism's dry weight. They function as enzymes, antibodies, and hormones, critical for various biological processes.

Structure of Proteins:

Proteins are made of amino acids, which include an amino group, a carboxylic acid group, and a unique R group.

  1. Primary Structure: Linear sequence of amino acids.

  2. Secondary Structure: Initial folding into alpha helices and beta-pleated sheets.

  3. Tertiary Structure: Three-dimensional shape due to R group interactions.

  4. Quaternary Structure: Combination of multiple polypeptide chains to form a functional protein.

Nucleic Acids

Nucleic acids, the largest biomolecules, consist of nucleotides made up of a nitrogenous base, a sugar (ribose or deoxyribose), and a phosphate group. Their primary function is to store and transmit genetic information.

  • DNA (Deoxyribonucleic Acid): A double-stranded helix that carries instructions for protein synthesis with base pairing (A-T, G-C).

  • RNA (Ribonucleic Acid): Single-stranded and involved in protein synthesis. Types include:

    • mRNA: Copies genes and directs amino acid sequences.

    • tRNA: Translates nucleotides to amino acids.

    • rRNA: Forms peptide bonds.

Adenosine Triphosphate (ATP)

ATP is a nucleotide with three phosphate groups that serves as the cell's energy currency. Energy is released when phosphate bonds break, powering cellular processes.

Key Points

  • Carbohydrates: Energy sources (e.g., glucose, starch).

  • Lipids: Energy-dense compounds for storage and insulation.

  • Proteins: Perform enzymatic and structural functions.

  • Nucleic Acids: DNA and RNA are key for genetic information; DNA is double-stranded, RNA is single-stranded.

ATP is essential for various cellular functions and macromolecule synthesis.