Cellular Metabolism

How do cells obtain energy from food?

A. Types of metabolism

  1. Autotrophs
    1. Absorption of nutrients
    2. Photosynthesis
  2. Heterotrophs
    1. Digestion
    2. Transport
    3. Cellular Respiration
    4. Fermentation
  3. Metabolism in ecosystems
    1. Consumers
    2. Producers

B. How cells produce energy

  1. Digestion of food
    1. Protein
    2. Fats
    3. Carbohydrates
      • Which of these gives you the most energy?
  2. Transporting food into the cell
    1. Facilitated diffusion
    2. Phagocytosis
  3. Cellular Respiration

    Step 1: Glycolysis

    1. Occurs in cytoplasm
    2. Produces 2 pyruvate + 2 ATP

    Step 2: Krebs cycle

    1. Occurs in mitochondria
    2. Uses pyruvate, makes CO2

    Step 3: Electron Transport Chain

    1. Occurs in mitochondria
    2. Uses electron flow to make ATP
    3. Where do all the electrons come from?
  4. Fermentation: When you're not using oxygen
    1. Glycolysis does not use oxygen
    2. Glycolysis gives off 2 ATP
    3. Pyruvate becomes a waste material
      • Lactic acid
      • Ethanol
      • Acetone
    4. Fermentation is used to make:
  5. Unusual metabolism: The world of prokaryotes
    1. Life without oxygen: Strict anaerobes
    2. Facultative anaerobes can do it all
    3. Bacteria that live on ammonia, methane, or sulfur
Applications
  1. Nutrition and calories
  2. Exercise - feeling the burn
  3. Alcohol, dairy and bread production
  4. Life on the early Earth: The worst case of environmental poisoning