Metabolism Overview

Metabolism Overview

  • Metabolism: Total set of life-sustaining chemical reactions in organisms.
  • Metabolic Pathways: Sequences of reactions, including catabolism (breakdown) and anabolism (building up).

Key Concepts

  • ATP Formation: ATP formed from ADP + inorganic phosphate (Pi).
  • CoA: Transfers acyl groups, essential in metabolic reactions.
  • Coenzymes: NAD+/NADH and FAD/FADH2 in electron transfer; oxidized forms are NAD+ and FAD, reduced forms are NADH and FADH2.

Metabolic Pathways

  • Types of Pathways:
    • Linear (e.g., glycolysis)
    • Circular (e.g., citric acid cycle)
    • Spiral (e.g., β-oxidation of fatty acids)

Carbohydrate Digestion and Metabolism

  • Digestion produces monosaccharides (e.g., glucose).
  • Glycolysis: Converts glucose to pyruvate (2 ATP and 2 NADH net gain).

Pyruvate Fate

  • Aerobic: Converts to acetyl-CoA.
  • Anaerobic: Converts to lactate.

Blood Glucose Regulation

  • Hormonal Control:
    • Insulin: Lowers blood glucose; activates glycogenesis.
    • Glucagon: Raises blood glucose; activates glycogenolysis and gluconeogenesis.

Fatty Acid Metabolism

  • Lipolysis: Breakdown of triglycerides to free fatty acids.
  • β-Oxidation: Converts fatty acids to acetyl-CoA, producing NADH and FADH2.

Protein Metabolism

  • Proteins digested to amino acids, which can be used for energy or biosynthesis.
  • Transamination & Deamination: Key reactions in amino acid catabolism.

Summary

  • Metabolic processes are tightly regulated to maintain homeostasis. ATP is the primary energy currency, with NADH and FADH2 serving as key energy carriers during oxidation and phosphorylation processes.