Lipid 2

• What is the primary source of energy for living organisms?

  Carbohydrates
• What determines the relative contribution of different energy pathways?

  Exercise intensity and physiological conditions
• What are the four energy pathways used by cells?

  • Carbohydrates
  • Fats
  • Proteins
  • Lactic acid
• What are the three phases of lipid catabolism?

  1. Storage
  2. Mobilization
  3. Oxidation
• Why are TAGs good storage forms of energy?

  They store fatty acids efficiently in adipocytes
• What is the role of hormone-sensitive lipase (HSL)?

  Hydrolyze TAG to FFA and glycerol
• What happens during the mobilization phase of lipid catabolism?

  Fatty acids and glycerol are released for energy
• What is the function of adipose triglyceride lipases (ATGL)?

  Hydrolyze TAG to DAG and FFA
• What occurs at the starvation phase regarding hormones and adipocytes?

  Hormones bind to receptors, activating lipolysis
• What are the steps involved in the oxidation of fatty acids?

  1. Oxidation by FAD
  2. Hydration
  3. Oxidation by NAD
  4. Thiolysis
• What is the major pathway for saturated fatty acids oxidation?

  β-oxidation
• What is the energy yield from one molecule of palmitate (C16) in ATP?

  131 ATPs
• How does the oxidation of odd-chain fatty acids differ from even-chain fatty acids?

  Odd-chain produces propionyl CoA instead of acetyl CoA
• What is the role of carnitine in fatty acid metabolism?

  Transport long-chain acyl-CoA into mitochondria
• What are the steps in the Carnitine Transport System?

  1. Carnitine acyl transferase 1 forms acyl-carnitine
  2. Translocase moves acyl-carnitine into matrix
  3. Carnitine acyl transferase 2 releases free carnitine
• What is the net ATP yield from the complete oxidation of palmitate?

  129 ATPs
• What is the function of acyl dehydrogenase in fatty acid oxidation?

  Oxidizes fatty acids to form FADH2
• What diseases are associated with abnormalities in lipid oxidation?

  • Carnitine transport system disorder
  • Carnitine deficiency
  • Muscle weakness
  • Heart or liver problems
• How does the oxidation of polyunsaturated fatty acids differ from monounsaturated fatty acids?

  Requires isomerization and additional enzymes
• What is the significance of the β-methyl branch in phytanic acid oxidation?

  It requires α-oxidation instead of β-oxidation
• What are the definitions of Acyl CoA and Acetyl CoA?

  • Acyl CoA: Activated fatty acid of varying carbon length
  • Acetyl CoA: 2 carbons, R=1