Aerobic respiration

• step 1 - Glycolysis

  
  

  Glucose + ATP -> glucose-6-phosphate -> fructose-6-phosphate -> Fructose 1,6-diphosphate -> 2x Glyceraldehyde 3-phosphate -> (2Pi -> 2 x NADH) 2x 1,3-diphosphoglycerate -> (byproduct = 2 x ATP) 2 x 3-phosphoglycerate -> 2x 2-phosphoglycerate -> Phosphoenolpyruvate -> 2x pyruvate + (2 x ATP as byproduct)
• step 2 - Link reaction

  1. Pyruvate moves into mitochondria with reduced NAD

  2. Pyruvate + NAD+CoA-SH -> Acetyl-S-CoA + NADH+H++CO₂

  reaction involves:

  • Oxidation
  • Decarboxylation
  • Catalysed by Pyruvate dehydrogenase (consists of 3 enzyme active sites)
• step 3 - Beta oxidation (respiration of fatty acids)

  • starts in the outer mitochondrial matrix
  • Fatty acids activated by conversion to fatty acyl-coenzyme A
  • each fatty acid-activated uses 1 molecule of CoA and 1 x ATP
  • Fatty acyl-CoA diffuses to the inner mitochondrial membrane combining with carnitine (a carrier molecule)
  • acyl-carnitine is transported into the mitochondrial matrix and converted back to fatty acid acyl-CoA
• • Ethanol -> Ethanal -> Ethonoate -> Acetyl CoA
  • Ethanol can lead to fatty liver, cirrhosis and death
• step 4 - Krebs cycle

  1. Acetyl CoA + oxaloacetate -> citrate -> isocitrate

  2. Isocitrate is oxidised to alpha-ketoglutarate

  4. Alpha-ketoglutarate + coenzyme A -> succinylcholine CoA + NADH + CO2

  5. Succinyl CoA -> succinate + GTP + CO2 (GTP transfers a Pi to ADP to make ATP)

  6. Succinate converts to fumarate + FADH2

  7. Fumarate -> malate

  8. Malate -> oxaloacetate + NADH
• Ketosis

  • ketones in the blood
  • ketogenesis occurs when your body respires fat for energy instead of glucose
• Oxidative phosphorylation - ETC


  • occurs on the cristae
  • Electrons from NADH2 and FADH2 pass along the electron transport chain carriers by a series of redox reactions catalysed by oxidoreductases
  • Electrons give off energy used to pump H+ into intermembrane space creating an electrochemical gradient
  • H+ moves back through creating ATP synthase to spin generating ATP (ADP + Pi -> ATP)
  • electrons, H+ and oxygen join to form H2O
• • Harmful byproducts of oxidative phosphorylation include free radicals which contain unpaired electrons picked up from lost electrons in the ETC
  • unstable and seek out other electrons
  • associated with cancer, atherosclerosis, Alzheimer's, Parkinson's
  • linked to aging
• Uncoupling oxidating phosphorylation - naturally

  • Splits oxidative ETC producing ATP
  • occurs naturally in the body (brown fat)
  • mitochondria have UPC1 (uncoupling protein 1) or thermogenin
  • allows rapid heat production
  • possible cure to obesity
• Uncoupling oxidative phosphorylation - artificially

  • DNP (Dinitrophenol) uncouples oxidative phosphorylation and binds to H+
  • is an ionophore-lipid, soluble so can diffuse through the membrane
  • H+ gradient is lost so ATP cannot be generated
• Mitochondrial diseases caused by mutations in mitochondrial DNA, part of autosomal inheritance

  • linked to autism
• Overcoming mitochondrial disease

  3 parent babies

  • pronuclear transfer
  • involves fertilising both the mothers and donor egg with the farthers sperm, enucleation of mitochondria via egg fusion