TR

Properties of Water, Biomolecules, and Enzymes Review

Properties of Water

  • Composition: Water (H_2O) is made of Hydrogen and Oxygen.

  • Bonds:

    • Between atoms (within H_2O): Covalent bonds (strong).

    • Between water molecules: Hydrogen bonds (weaker, connect molecules like magnets).

  • Polarity: Water is a polar molecule due to unequal sharing of electrons in its covalent bonds.

  • Key Properties:

    • Cohesion: Water molecules attract other water molecules.

    • Adhesion: Water molecules attract other substances (e.g., xylem).

    • Surface Tension: The property allowing a liquid to resist external force, resulting from cohesion.

    • Capillary Action: Water moves against gravity, driven by cohesion and adhesion.

    • Universal Solvent: Water dissolves many substances.

    • Each water molecule can form up to 4 hydrogen bonds.

Biomolecules (Macromolecules)

  • Molecules found in living organisms, essential for life.

  • Monomer: A small molecular unit.

  • Polymer: A long chain formed by linking multiple monomers.

  • Main Types:

    • Carbohydrates:

      • Monomer: Monosaccharides (e.g., glucose).

      • Polymer: Disaccharides (e.g., sucrose, lactose) or Polysaccharides.

    • Lipids (Fats):

      • Do not typically form polymers from monomers in the same way as other biomolecules.

      • Function: Store long-term energy.

      • Characteristics: Contain hydrophobic and hydrophilic parts (e.g., saturated fatty acids).

Enzymes

  • Nature: Protein molecules that act as biological catalysts.

  • Catalyst: A substance that speeds up chemical reactions without being consumed in the process.

  • Nomenclature: Enzyme names often end in "-ase" (e.g., Lactase).

  • Mechanism (Lock and Key Model):

    1. Substrate (reactants) binds to the enzyme's specific active site.

    2. The chemical reaction proceeds.

    3. Products are released.

  • Specificity: Enzymes are specific in the reactions they catalyze due to their unique shapes.

  • Environmental Sensitivity: Enzymes function optimally under specific environmental conditions (temperature, pH).

  • Denaturation: If an enzyme is in an unsuitable environment, it loses its specific shape and function, becoming denatured (useless).

  • Location: Commonly found in the digestive system, where they break down food.