Biosynthesis and Storage Pathways in Metabolism 🍽️

Introduction

• Purpose: Understanding what happens to excess energy from consumed food.
• Goal: Explain where and how excess energy is stored in the body.
• Importance: Relates to the First Law of Thermodynamics, nutritional composition of food, and metabolic pathways.

Key Concepts

Biosynthetic Pathways

• Definition: Production of complex molecules within living organisms.
• Dominance depends on energy needs and availability:
  • Breakdown Pathways vs. Biosynthetic Pathways

Glycogenesis

• Definition: Assembles glucose into branched chains for storage.
• Process: Converts glucose to glycogen for storage in liver and muscles.
• Concept: Glycogen is the storage form of glucose.

Gluconeogenesis

• Definition: Creation of glucose from non-carb sources (proteins, amino acids, lactic acids, glycerol).
• Key Points:
  • Fatty acids cannot be converted to glucose.
  • Glucose production from pyruvate occurs mainly in the liver (90%) and kidneys (10%) during intense exercise or insufficient carb intake.
  • Over-reliance on gluconeogenesis (e.g., extreme diets) can stress the liver.

Lipogenesis

• Definition: Accelerated during excess energy intake, leading to fat tissue.
• Process: Converts acetal COA molecules into fatty acids for storage as body fat.
• Sources: Excess carbs, proteins, alcohol, and fats can all contribute to lipogenesis.
• Concept: When energy intake exceeds ATP demands, the body efficiently stores excess as fat.

Practical Implications

• Consumption and Storage: Excess intake of carbs, protein, alcohol, or fat leads to fat storage.
• Dietary Considerations: Understanding metabolic pathways can help in making informed dietary choices.

Summary

• Review: Revisit initial questions about energy storage and usage.
• Questions Encouraged: Reach out for clarifications.