Key Concepts in Cellular Respiration

Overview of Cellular Respiration

• Mitochondria: Known as the powerhouse of the cell, they are essential for energy conversion from food and oxygen into ATP.
• Cellular Respiration: A vital process that converts food and oxygen into energy (ATP) for cell functions.

Energy Storage and Use

• ATP (Adenosine Triphosphate):
• Acts like a rechargeable battery in cells.
• Essential for processes maintaining homeostasis (body’s stability).
• Average human utilizes over a hundred pounds of ATP daily.

The Process of Cellular Respiration

• Aerobic Organisms: Rely on oxygen for energy release (e.g., humans, animals, plants).
• Anaerobic Respiration: Some organisms can respire without oxygen (e.g., certain bacteria); linked to fermentation (e.g., sourdough, kimchi).
• Waste Products: Carbon dioxide and water are produced during respiration.

Metabolic Pathways

• Cellular respiration is a series of metabolic pathways that occur in three stages:

1. Glycolysis
2. Citric Acid Cycle (Krebs Cycle)
3. Oxidative Phosphorylation

1. Glycolysis

• Location: Cytoplasm of the cell.
• Process:
• Breaks down glucose into pyruvate through 10 enzymatic reactions.
• Produces net 2 ATP and NADH (a carrier for electrons).
• Function: Converts glucose to a usable form of energy (pyruvate).

2. Citric Acid Cycle (Krebs Cycle)

• Location: Mitochondria.
• Process:
• Pyruvate is further broken down into carbon dioxide.
• Produces 1 ATP, 3 NADH, and FADH2 during each cycle.
• Cycle Mechanism:
• A two-carbon molecule combines with a four-carbon molecule to start the cycle, and eventually regenerates the original four-carbon molecule.

3. Oxidative Phosphorylation

• Location: Inner mitochondrial membrane.
• Function:
• Electron transport chain and ATP synthase are crucial for ATP production.
• Electrons are transferred through proteins, creating a proton gradient.
• The flow of protons back into the matrix through ATP synthase generates about 30 ATP molecules per glucose.
• Final products: Remaining electrons combine with oxygen, forming water (H2O).

Summary of Cellular Respiration

• Overall Process: Glycolysis ➔ Citric Acid Cycle ➔ Electron Transport Chain (Oxidative Phosphorylation).
• Net Gain: Approximately 30 ATP molecules produced from one glucose molecule.

Importance of Mitochondria

• Mitochondria are crucial for ATP generation and energy supply in cells, affecting overall cellular function and survival.
• The entire process occurs rapidly, producing around 10 million ATP molecules per second in a single cell.

Future Topics

• Next session will cover photosynthesis, the critical process for life on Earth.