Metabolic Pathways Overview

Metabolic Pathways

• Definition: Series of biochemical reactions that convert a substrate into a product within a cell, involving various enzymes.

• Types of Metabolic Pathways:

  1. Catabolic Pathways:

     • Break down molecules to produce energy (ATP).
     • Example: Glycolysis, Citric Acid Cycle (Krebs Cycle).

  2. Anabolic Pathways:

     • Build complex molecules from simpler ones, requiring energy.
     • Example: Protein synthesis, Glycogenesis.

• Key Metabolic Pathways:

  1. Glycolysis:

     • Breakdown of glucose into pyruvate.
     • Occurs in the cytoplasm; net gain of 2 ATP.

  2. Citric Acid Cycle (Krebs Cycle):

     • Completes the oxidation of substrates derived from glycolysis.
     • Produces NADH, FADH2, and ATP; occurs in the mitochondria.

  3. Oxidative Phosphorylation:

     • Uses electrons from NADH and FADH2 to generate ATP via the electron transport chain.
     • Involves chemiosmosis and occurs in the inner mitochondrial membrane.

  4. Photosynthesis (for plants):

     • Converts light energy into chemical energy.
     • Occurs in chloroplasts; involves light-dependent and light-independent reactions (Calvin Cycle).

• Regulation of Metabolic Pathways:

  • Enzyme activity modulation through:
    • Allosteric regulation: Enzymes change shape upon substrate binding.
    • Feedback inhibition: End products inhibit early steps (e.g., ATP inhibiting phosphofructokinase in glycolysis).

• Metabolic Disorders:

  • Result from enzyme deficiencies (e.g., phenylketonuria from phenylalanine hydroxylase deficiency).
  • Can lead to accumulation of substrates or deficits in products.

• Importance of Metabolic Pathways:

  • Energy production for cellular functions.
  • Synthesis of biomolecules necessary for growth and maintenance.
  • Integration of various metabolic processes to maintain homeostasis.

Metabolic Pathways

• Series of biochemical reactions converting substrates into products, involving enzymes.

Types of Metabolic Pathways

• Catabolic Pathways:

  • Decompose molecules to release energy in the form of ATP.
  • Examples include glycolysis and the citric acid cycle (Krebs cycle).

• Anabolic Pathways:

  • Synthesize complex molecules from simpler ones, consuming energy.
  • Examples include protein synthesis and glycogenesis.

Key Metabolic Pathways

• Glycolysis:

  • Converts glucose into pyruvate.
  • Occurs in the cytoplasm, yielding a net gain of 2 ATP.

• Citric Acid Cycle (Krebs Cycle):

  • Finalizes the oxidation of substrates from glycolysis.
  • Produces NADH, FADH2, and ATP, taking place in the mitochondria.

• Oxidative Phosphorylation:

  • Utilizes electrons from NADH and FADH2 to generate ATP along the electron transport chain.
  • Involves chemiosmosis and occurs in the inner mitochondrial membrane.

• Photosynthesis (in plants):

  • Transforms light energy into chemical energy.
  • Occurs in chloroplasts; comprises light-dependent and light-independent reactions (Calvin Cycle).

Regulation of Metabolic Pathways

• Modulated through:
  • Allosteric Regulation: Enzymes alter shape when substrates bind.
  • Feedback Inhibition: End products inhibit earlier steps, such as ATP inhibiting phosphofructokinase during glycolysis.

Metabolic Disorders

• Arise from enzyme deficiencies (e.g., phenylketonuria due to a deficiency of phenylalanine hydroxylase).
• Can cause substrate accumulation or product deficits.

Importance of Metabolic Pathways

• Essential for energy production to support cellular functions.
• Facilitate biosynthesis of necessary biomolecules for growth and maintenance.
• Ensure integration of various metabolic processes to uphold homeostasis.

Explore the key concepts of metabolic pathways, including catabolic and anabolic processes essential for energy production. Understand specific pathways like glycolysis, the citric acid cycle, and oxidative phosphorylation. This quiz will enhance your knowledge of cellular metabolism.