• Process of converting glucose into energy

• Involves glycolysis, Krebs cycle, and electron transport chain

• Takes place in the mitochondria of cells

• Generates ATP for cellular functions

• Releases carbon dioxide and water as byproducts

• Requires oxygen as the final electron acceptor

• Essential for the survival of aerobic organisms

• Regulation of cellular respiration by hormones and enzymes

• Importance of balanced diet and exercise for optimal respiration

• Dysfunction in cellular respiration linked to various diseases

1. Overview of Cellular Respiration

• Definition: Cellular respiration is the process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water.

• Purpose: Understand the primary goal of cellular respiration, which is to produce ATP, the energy currency of the cell.

2. Stages of Cellular Respiration

• Glycolysis

  • Location: Cytoplasm

  • Key Events: Breakdown of glucose into two molecules of pyruvate

  • ATP Yield: 2 ATP (net gain)

  • Products: 2 Pyruvate, 2 NADH, 2 ATP

• Krebs Cycle (Citric Acid Cycle)

  • Location: Mitochondrial matrix

  • Key Events: Pyruvate is converted to Acetyl-CoA, which enters the cycle; release of carbon dioxide

  • ATP Yield: 2 ATP per glucose molecule

  • Products: NADH, FADH2, CO2, ATP

• Electron Transport Chain (ETC) and Oxidative Phosphorylation

  • Location: Inner mitochondrial membrane

  • Key Events: Electrons from NADH and FADH2 pass through protein complexes, creating a proton gradient

  • ATP Yield: Approximately 32-34 ATP

  • Final Electron Acceptor: Oxygen, which forms water

3. Inputs and Outputs

• Overall Reaction: C6H12O6+6O2→6CO2+6H2O+ATP\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}C6​H12​O6​+6O2​→6CO2​+6H2​O+ATP

• Inputs: Glucose, Oxygen

• Outputs: Carbon dioxide, Water, ATP

4. ATP Production

• Substrate-level phosphorylation: Direct synthesis of ATP during glycolysis and Krebs cycle.

• Oxidative phosphorylation: ATP generation in the ETC driven by the proton gradient created by electron transfer.

5. Fermentation

• Anaerobic Respiration: Occurs when oxygen is not available

  • Lactic Acid Fermentation: Occurs in muscle cells; pyruvate is reduced to lactic acid.

  • Alcoholic Fermentation: Occurs in yeast; pyruvate is converted to ethanol and CO2.

• ATP Yield: Much lower than aerobic respiration (only 2 ATP per glucose molecule)

6. Mitochondria Structure

• Outer Membrane: Smooth, protective membrane.

• Inner Membrane: Folded into cristae, where the ETC is located.

• Matrix: Contains enzymes for the Krebs cycle.

7. Redox Reactions

• NAD+ and FAD: Electron carriers that get reduced to NADH and FADH2.

• Role of Oxygen: Final electron acceptor in the ETC.

8. Regulation of Cellular Respiration

• Feedback Mechanisms: How ATP, ADP, NADH, and other molecules regulate the rate of cellular respiration.

9. Connection to Photosynthesis

• Interdependence: How the products of photosynthesis (glucose and oxygen) are used in cellular respiration, and the products of respiration (carbon dioxide and water) are used in photosynthesis.

10. Practical Applications and Experiments

• Experiments: Be familiar with lab experiments related to cellular respiration, such as measuring oxygen consumption, carbon dioxide production, or using respirometers.