Chapter 7: Cellular Respiration Study Guide

🔑 Core Concepts & Definitions

1. Cellular Respiration

• Definition: The process by which cells extract energy from glucose to produce ATP.

• Significance: Essential for powering cellular activities.

• Equation:

  C6H12O6+6O2→6CO2+6H2O+ATPC6​H12​O6​+6O2​→6CO2​+6H2​O+ATP

⚡ Redox Reactions in Cellular Respiration

2. Oxidation

• Definition: Loss of electrons.

• Connection: Glucose is oxidized during cellular respiration.

3. Reduction

• Definition: Gain of electrons.

• Connection: Oxygen is reduced to water.

4. Electron Carriers (NAD+ / NADH & FAD / FADH₂)

• Definition: Molecules that transport electrons during redox reactions.

• Significance: Carry high-energy electrons to the electron transport chain (ETC).

• NAD+: Accepts electrons and becomes NADH.

• FAD: Becomes FADH₂ after gaining electrons.

• Related To: ETC, ATP production, oxidation/reduction.

⚙ Phases of Cellular Respiration

5. 1. Glycolysis

• Location: Cytoplasm

• Products: 2 ATP (net), 2 NADH, 2 Pyruvate

• Significance: First step, no oxygen required.

• Connection: Leads into pyruvate oxidation.

6. 2. Pyruvate Oxidation (Link Reaction)

• Location: Mitochondrial matrix

• Process: Pyruvate → Acetyl-CoA + CO₂ + NADH

• Significance: Connects glycolysis to the citric acid cycle.

7. 3. Citric Acid Cycle (Krebs Cycle)

• Location: Mitochondrial matrix

• Products per glucose: 6 NADH, 2 FADH₂, 2 ATP, 4 CO₂

• Cycle: Regenerates oxaloacetate.

• Connection: Feeds electrons to ETC.

8. 4. Oxidative Phosphorylation

• Steps: Electron Transport Chain + Chemiosmosis

• Location: Inner mitochondrial membrane

• Function: Major ATP production site (~28 ATP)

• Requires: NADH & FADH₂

🌀 Energy Production & ATP Synthesis

9. Substrate-Level Phosphorylation

• Definition: Direct transfer of phosphate to ADP.

• Occurs In: Glycolysis and Citric Acid Cycle.

10. Oxidative Phosphorylation

• Definition: ATP generation using energy from electron transfer and proton gradient.

• Occurs In: ETC and chemiosmosis.

11. Chemiosmosis

• Definition: H+ ions flow through ATP synthase to generate ATP.

• Connection: Uses the proton gradient from ETC.

12. ATP Synthase

• Structure: Two subunits—F₀ (channel) & F₁ (ATP production)

• Function: Synthesizes ATP as protons flow through.

🔁 Electron Transport Chain (ETC)

13. ETC

• Definition: Series of protein complexes transferring electrons.

• Creates: Proton gradient across inner membrane.

• Final Electron Acceptor: O₂ → H₂O

🔁 Alternate Pathways

14. Fermentation

• Anaerobic: No oxygen required.

• Lactic Acid Fermentation: Pyruvate → Lactate (e.g., in muscles).

• Alcohol Fermentation: Pyruvate → Ethanol + CO₂ (e.g., in yeast).

• Connection: Regenerates NAD+ for glycolysis.

15. Aerobic vs Anaerobic Respiration

• Aerobic: Uses oxygen, high ATP yield (~32-34).

• Anaerobic: Without oxygen, low ATP yield (2 ATP).

🍽 Metabolism of Other Molecules

16. Lipids

• Broken Down Into: Glycerol and fatty acids.

• ATP Yield: Higher than glucose per molecule.

17. Proteins

• Broken Down Into: Amino acids → feed into glycolysis or citric acid cycle.

• Note: Must remove nitrogen first (deamination).

18. Carbohydrates

• Primary Fuel: Broken into glucose for glycolysis.

🧠 Concept Connections & Integration

• Redox reactions fuel electron carriers → drive ETC.

• ETC generates proton gradient → powers chemiosmosis → produces ATP.

• Glycolysis is the common entry point for various food molecules.

• Pyruvate’s fate depends on oxygen availability → aerobic (acetyl-CoA) or anaerobic (lactate/ethanol).

• ATP yield varies based on the respiration pathway used.