Recap: structure of ATP P P P riboseguanineinorganic phosphate deoxyribosethymine organic phosphate nicotinamidecytosineadenineflavine

Recap: where in the cell? 1.Glycolysis 1.Phosphorylation 2.Oxidation 2.Link reaction 3.Krebs cycle 4.Oxidative phosphorylation

Recap: glycolysis

Recap: link reaction

Recap: Krebs cycle

Enzymes Glycolysis: –Phosphofructokinase Krebs cycle: –Decarboxylases –Dehydrogenases

Regulatory enzymes glucose phosphofructokinase enzyme pyruvate Krebs cycle ↑ ATP ↑ citrate ↑ ADP ↓ ATP ↓ citrate

How much ATP has been produced? Glycolysis: Link reaction: Krebs cycle: Is this enough???

The electron transport chain

1.Hydrogen atoms released from NADH and FADH as they are oxidised 2.Hydrogen atoms split into protons and electrons 3.Electrons move along the electron transport chain, losing energy at each carrier 4.Energy is used to pump protons into intermembrane space forming an electrochemical gradient 5.Protons move down electrochemical gradient back to matrix via ATP synthase 6.Movement of protons drives synthesis of ATP from ADP and inorganic phosphate 7.Protons, electrons and oxygen combine to form water, the final electron acceptor

Evidence for chemiosmosis 1.pH of intermembrane space is lower than pH of matrix –Proton gradient exists between intermembrane space and matrix 2.Artificial vesicles created with proton pump proteins resulted in ↓ pH in vesicle –Proton gradient can be used to synthesise ATP 3.Mitochondria in pH8 solution produced no ATP –Proton gradient can be used by mitochondria to make ATP 4.Uncouplers destroyed proton gradient in mitochondria –Proton gradient is required by mitochondria to make ATP

How much ATP? Oxidative phosphorylation makes ATP using energy from NADH and FADH 1 NADH → 2.5 ATP 1 FADH → 1.5 ATP More cutbacks: In NADH → 3 ATP and 1 FADH → 2 ATP!

How much ATP? Stage of respirationMolecules producedNumber of ATP molecules Glycolysis Link reaction (x2) Krebs cycle (x2) Total ATP =

Anaerobic respiration glucose pyruvate carbon dioxide + ethanal ethanol lactic acid

Aerobic and anaerobic respiration Aerobic Where? Is oxidation complete? What are the waste products? How much energy? Anaerobic Where? Is oxidation complete? What are the waste products? How much energy?