000 CellularRespiration

Chapter 6: How Cells Harvest Chemical Energy

Overview

  • Title: Cellular Respiration: Aerobic Harvesting of Energy

  • Focus on how living organisms obtain and utilize energy

Big Ideas

  • Cellular Respiration: Process of breaking down glucose to harvest chemical energy.

    • Aerobic Respiration: Requires oxygen.

    • Fermentation: Anaerobic process; does not require oxygen.

  • Connection between metabolic pathways that illustrate energy flow in ecosystems.

Cellular Respiration Overview

  • Comparison of Reactants and Products in Photosynthesis vs Cellular Respiration.

  • Structure of Mitochondria: Key in ATP production, linked to its function.

Energy Flow in Ecosystems

Photosynthesis in Chloroplasts

  • Light energy converted into chemical energy.

  • Inputs: CO2 and H2O

  • Outputs: Sugar and O2

Cellular Respiration in Mitochondria

  • Inputs: Organic molecules and O2

  • Outputs: CO2, H2O, ATP, heat energy

  • ATP: Powers most cellular work; approximately 34% efficiency.

Key Processes in Cellular Respiration

Breathing vs Cellular Respiration

  • Breathing: Gas exchange; supplies O2 and removes CO2.

  • Cellular Respiration: Aerobic breakdown of food molecules for energy.

Energy Production

ATP Molecules

  • Exergonic Process: Energy-releasing reaction.

    • Can produce up to 38 ATP molecules per glucose molecule.

    • 60% of energy lost as heat during metabolism.

  • Importance of regulating energy and maintaining balance to support bodily functions.

Types of Cellular Respiration

Aerobic vs Anaerobic

  • Aerobic Respiration: Uses oxygen; more efficient.

  • Anaerobic Respiration: Does not require oxygen; less efficient.

Stages of Aerobic Cellular Respiration

  1. Glycolysis

    • Location: Cytoplasm

    • Process: Breakdown of glucose into pyruvate.

    • Yield: 2 ATP, 2 NADH.

  2. Krebs Cycle (Citric Acid Cycle)

    • Location: Mitochondrial matrix

    • Process: Extract energy from pyruvate, producing NADH and FADH2.

    • Yield: 2 ATP, 6 NADH, 2 FADH2.

  3. Electron Transport Chain / Oxidative Phosphorylation

    • Location: Inner mitochondrial membrane (cristae)

    • Process: Converts energy from electrons to ATP.

    • Yield: Up to 32 ATP.

Mechanisms of Cellular Respiration

Redox Reactions

  • Oxidation/Reduction: Loss and gain of electrons during metabolic reactions.

  • Nomenclature:

    • LEO = Lose Electrons Oxidation

    • GER = Gain Electrons Reduction

  • Role of Dehydrogenase and NAD+ in electron transport.

Mitochondria: The Powerhouse

  • Function: ATP synthesis using high surface area inner membrane.

  • Importance of mitochondria in converting energy through cellular respiration.

Final ATP Tally for Cellular Respiration

  • Total ATP production from the different stages:

    • Glycolysis: 2 ATP

    • Krebs Cycle: 2 ATP

    • Electron Transport Chain: Up to 32 ATP

  • Overall energy flow highlighted through these processes.

Fermentation: Anaerobic Harvesting of Energy

Overview

  • Begins with Glycolysis; pathways depend on organism type.

    • Modes: Alcoholic Fermentation, Lactic Acid Fermentation.

  • Total yield: 2 ATP.

Types of Fermentation

  1. Lactic Acid Fermentation

    • In muscle cells under O2 shortage.

    • By-products: Lactic acid.

  2. Alcoholic Fermentation

    • Carried out by yeasts and bacteria.

    • By-products: Ethanol and CO2.

Utilization of Organic Molecules

  • Cells can use carbohydrates, fats, and proteins as fuel.

  • Breakdown to produce ATP.

Concluding Concepts

  1. Compare processes of cellular respiration and photosynthesis.

  2. Explain relation of breathing to cellular respiration.

  3. Provide the overall equation for cellular respiration.

  4. Describe human body’s ATP use and the role of redox reactions.

  5. Compare yields of aerobic cellular respiration and fermentation.