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.