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.
- Cellular respiration is a series of metabolic pathways that occur in three stages:
- Glycolysis
- Citric Acid Cycle (Krebs Cycle)
- 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.