Biology Unit 3: Macromolecules and Enzyme Function

Basic Concepts of Macromolecules

  • Monomer vs Polymer
    • Monomer: Basic unit; example: monosaccharides for carbohydrates.
    • Polymer: Long chain of monomers; example: polysaccharides made of multiple monosaccharides.

Essential Elements for Life

  • Four Essential Elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N).
  • These elements combine to create vital macromolecules required for life processes.

Macromolecules

  • Four Main Macromolecules:
    • Carbohydrates
    • Lipids
    • Proteins
    • Nucleic Acids
  • Polymers are often constructed from monomers, which are repeating units that serve as building blocks.

Carbohydrates

  • Composition: Primarily made of carbon, hydrogen, and oxygen.
  • Monomers: Monosaccharides (e.g., glucose: C6H{12}O_6).
    • Simple Sugars: Glucose, fructose (one monomer).
    • Disaccharides: Formed from two monosaccharides (e.g., lactose).
  • Polysaccharides: Many monosaccharides linked together. Examples include:
    • Starch: Energy storage in plants.
    • Cellulose: Structural component of plant cell walls.
    • Glycogen: Energy storage in animals (found in liver and muscle).

Lipids

  • Composition: Primarily carbon, hydrogen, and oxygen.
  • Monomers: Glycerol and fatty acids (not in chains but in an “E” shape).
  • Types of Lipids:
    • Triglycerides: Fats and oils for long-term energy storage.
    • Phospholipids: Form the bilayer of cell membranes.
    • Other Fats: Provide insulation and protection to organs.

Proteins

  • Composition: Contain carbon, hydrogen, oxygen, and nitrogen.
  • Monomers: Amino acids (20 types).
  • Structure: Amino acids bond to create polypeptides; the sequence determines protein shape and function.
  • Functions of Proteins:
    • Antibodies: Part of immune response.
    • Membrane Proteins: Assist in transport and cell communication.
    • Structural Proteins: e.g., keratin in hair.
    • Pigments: Absorb and reflect light.
    • Enzymes: Catalysts for chemical reactions; function depends on shape. Denaturation can occur if the protein unravels due to changes in pH or temperature.

Food Breakdown (Metabolism)

  • Chemical Reactions: Involved in breaking down food; supported by enzymes.
  • Enzymes: Biological catalysts that reduce the activation energy needed for reactions, functioning at specific temperatures and pH.
  • Enzyme-Substrate Interaction:
    • Each enzyme is specific to its substrate, fitting together like lock and key.
    • Active Site: The region on the enzyme where substrate binding occurs.

Enzyme Reaction Steps

  • Collisions between enzyme and substrate occur.
  • Enzyme changes substrate, forming products, and remains unchanged to catalyze further reactions.
  • Example Reaction: 2H2O2 + ext{catalase}
    ightarrow H2O + O2 + ext{catalase}

Homeostasis and Molecule Transport

  • Homeostasis: Maintaining internal stability; involves nutrient transport to cells.
  • Transport Mechanisms:
    • Passive Transport: No energy used; molecules move along concentration gradients (high to low concentration).
    • Active Transport: Requires energy; molecules move against concentration gradients (low to high concentration).

Osmosis and Diffusion

  • Diffusion: Movement of substances down their concentration gradient.
  • Osmosis: Diffusion of water across a membrane, influencing cell size and shape; water moves from areas of high concentration to low.

Transport Mechanisms Overview:

  • Passive Transport:
    • Concentration gradient guides movement (high to low).
  • Active Transport:
    • Utilizes energy (low to high).
  • Selectively Permeable Membrane: Allows certain materials through while blocking others.

Feedback Mechanisms

  • Example: pH balance via membrane proteins to maintain optimal conditions for cellular reactions.