Understanding Fatty Acid Metabolism

Sep 30, 2024

Lecture Notes: Fatty Acid Metabolism

Overview

  • Focus on fatty acids: what they are, their functions, breakdown, and synthesis.

What are Fatty Acids?

  • Composition: Long hydrocarbon chain with a terminal carboxylate group.
    • Terminal Carboxylate Group: Hydrophilic, polar properties.
    • Hydrocarbon Chain: Hydrophobic, non-polar properties.

Functions of Fatty Acids in Cells

  1. Fuel Molecules: Breakdown of fatty acids generates ATP.
  2. Cell Membrane Components: Building blocks for glycolipids and phospholipids.
  3. Protein Modification: Attaching fatty acids increases protein functionality.
  4. Hormones/Intracellular Messengers: Many hormones are built from fatty acids.

Breakdown of Fatty Acids

  • Process Overview: Oxidation, hydration, oxidation, cleavage.
    • Oxidative Process: Extraction of electrons.
    • Cycle: Shortens fatty acid chain by 2 carbons per cycle.
    • Begins with an activated fatty acid by attaching a coenzyme (e.g., R’ group).

Steps of Breakdown

  1. First Oxidation: Extraction of H atoms, formation of a double bond.
  2. Hydration: Addition of a hydroxyl group, breaking the pi bond.
  3. Second Oxidation: Converts hydroxyl to carbonyl group (forms ketone).
  4. Cleavage: Coenzyme A cleaves the bond, producing acetyl units.

Result

  • Acetyl Units: Enter the citric acid cycle, generating ATP.
  • Repeated cycles for fully saturated fatty acids with an even number of carbons.

Synthesis of Fatty Acids

  • Purpose: Occurs when ATP is abundant, for hormone production, protein modification, cell membrane building.
  • Process Mirror: Opposite of fatty acid breakdown.

Steps of Synthesis

  1. Condensation: Begins with activated acyl and malonyl units.
  2. First Reduction: Transformation of ketone to alcohol by adding electrons and H atoms.
  3. Dehydration: Removal of hydroxyl group, formation of a pi bond.
  4. Second Reduction: Final reduction step, formation of activated fatty acid.

Result

  • Increases Carbon Chain: By 2 carbons per cycle.
  • Reductive Process: Builds up hydrocarbon chains from acyl and malonyl units.

Summary

  • Breakdown: Oxidative; shortens chain by 2 carbons, generates ATP.
  • Synthesis: Reductive; lengthens chain by 2 carbons, opposite reactions of breakdown.
  • Detailed steps of synthesis to be covered in future lectures.