Cellular Respiration Part 4 Oxidative Phosphorylation Pages 98 to 100

Oxidative Phosphorylation Location ▫Cristae of mitochondria Final Acceptor of Electrons ▫Oxygen

Fig (from NADH or FADH 2 ) NADH NAD + 2 FADH 2 2 FAD Multiprotein complexes FA D Fe S FM N Fe S Q  Cyt b   Cyt c 1 Cyt c Cyt a Cyt a 3 IVIV Free energy (G) relative to O 2 (kcal/mol) H / 2 O2O2 H2OH2O e–e– e–e– e–e– Electrons are transferred from NADH or FADH 2 to the electron transport chain Electrons are passed through a number of proteins to O 2 The electron transport chain generates no ATP The chain’s function is to break the large free-energy drop from food to O 2 into smaller steps that release energy in manageable amounts

Electron transfer in the electron transport chain causes proteins to pump H + from the mitochondrial matrix to the intermembrane space Intermembrane space becomes positively charged; the matrix because negatively charged – concentration gradient is established = potential energy

Fig INTERMEMBRANE SPACE Rotor H+H+ Stator Internal rod Catalytic knob ADP + P ATP i MITOCHONDRIAL MATRIX As H+ escapes from positively charged intermembrane space through ATP Synthase to the negatively charged matrix, ATP synthase spins using energy released from H+ going down its concentration gradient to phosphorylate ADP making ATP Chemiosmosis is using energy of a H+ gradient to do cellular work

NADH makes 3 ATP; FADH 2 makes 2 ATP ProcessNADHFADH2ATP Glycolysis202 Krebs Cycle822 ETC & Chemiosmosis 10 X 3 = 302 X 2 = = 34 Debt (entering mitochondria) 2 ATP expended to transport NADH to ETC from cytoplasm -2 Total36 ATP Yield from 1 glucose

Certain Poisons Interrupt Events in Cellular Respiration

3 Categories of Poison ETC Inhibitors ▫Rotenone Blocks ETC at 1 st protein complex ▫Cyanide and CO2 block ETC at 3 rd protein complex  RESULT = no H+gradient  no ATP ATP synthase Inhibitors ▫Oligiomycin ▫Keep H+ from passing through ATP synthase  RESULT = no chemiosmosis

3 Categories of Poison Uncouplers ▫Make the membrane of the mitochondria “leaky” to H+ ▫Dintrophenol (DNP) unsuccessfully used for weight loss  RESULT – Can’t establish H+ gradeint  no ATP

Benefit of poisons… Pesticides Antibodies Help to understand the biochemistry of cellular respiration