Amino acids in the human body are not stored; instead, they are broken down and used for energy or fat storage.
The Fate of Amino Acids
When the body doesn't need amino acids for building proteins, they undergo a process called catabolism. Here's a detailed look at what happens to them:
Breakdown Pathways
- According to our reference, amino acids are broken down into:
- Pyruvate: An important three-carbon molecule in cellular metabolism.
- Acetyl CoA: A central molecule in energy production, particularly in the Krebs cycle.
- Intermediates of the Krebs cycle: Molecules directly involved in the citric acid cycle, the major pathway of energy production in the body.
Use For Energy
- The broken-down components can enter the Krebs cycle, also known as the citric acid cycle, to generate ATP, the main energy currency of the cell. This happens when the body needs immediate energy.
Lipogenesis (Fat Storage)
- When energy is plentiful, the broken-down components are used for lipogenesis. This is the process where excess acetyl CoA is converted into fatty acids, which are then stored as fats.
Detailed Breakdown Table
| Starting Molecule | Breakdown Product(s) | Purpose |
|---|---|---|
| Amino Acids | Pyruvate, Acetyl CoA, Krebs cycle intermediates | Energy production or conversion to fat |
Important Points
- No Storage: Unlike fats and carbohydrates, amino acids are not stored for later use, which is why it is crucial to have a regular intake of protein in your diet.
- Dynamic Processes: The body continuously breaks down and rebuilds proteins, making amino acids constantly available for different metabolic needs.
- Waste Products: When amino acids are broken down, nitrogenous waste products like urea are produced and excreted from the body, primarily through urine.
In essence, amino acids are used as building blocks for proteins, and if not needed for that purpose they are converted into molecules that either produce energy or are stored as fat.
