BIO 151 1st Edition Lecture 25 Outline of Last Lecture 1. Polyploidy 2. Imprinting3. Genes in semi-autonomous organelles - mitochondria, chlorplasts4. Non-DNA information?5. Semi-autonomous organelles6. Respiration7. What's all this about electrons?8. GlycylosisOutline of Current Lecture 1. Beginning of cycle2. Rest of cyclee3. Krebs cycle (know this)4. But...5. Intermembrane Space6. Oxidative Phosphorylation7. Electron Transport Chain8. Electrons in chain often carried by metal atoms9. Mitochondrial ATP synthase is a turbine10. 2 steps of oxidative phosphorylation11. How efficient is it?Current Lecture - next steps occur in mitochondrion- pyruvate enters mitochondrial matrix- get a couple high energy electrons- after entry, 3-carbon pyruvate loses 1 carbon as CO2 as it binds to coenzyme A to make acetyl-CoA- produces 1 NADH/pyruvate (2/glucose)- acetyl-CoA enters the Krebs Cycle (citric acid cycle) in mitochondrion matrix- acetyl-CoA adds its 2 carbons to 4 carbon oxaloacetate, making 6-carbon citric acidBeginning of cycle:- lose 2 carbons from 6-carbon molecule as CO2 to get 4-carbon molecules- get some electronsRest of cycle:- regenerate 4-carbon oxaloacetate- get ATP, more electronsKrebs Cycle (know this):- acetyl-CoA adds its 2 carbons to a 4-carbon oxaloacetate, making a 6-carbon citric acid (citrate)- cycle takes the 6-carbon and regenerates the 4-carbon by losing 2 CO2s- once through Krebs, yields 1 ATP, 3 NADH, 1 FADH2- glycolysis: glucose (6C) -> 2 pyruvates (3C x 2), yields 2 ATP, 2 NADH- binding coenzyme A (x2): 2 pyruvates -> 2 acetyl-CoA's (2C) + 2 CO2, yields 2 NADHThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Kreb's Cycle (x2): 2 acetyl CoA's -> 4 CO2, yields 2 ATP, 6 NADH, 2 FADH2- per glucose, glycolysis and Krebs cycle give 2 ATP each, 4 total- patheticBut...:- energy in electrons in NADH, FADH2- got 10 NADH, 2 FADH2 per glucose- convert energy to electrons to energy via oxidative phosphorylation (take electrons = oxidation, make ATP = phosphorylation)- 26-34 ATPs- high energy electrons in NADH, FADH2Intermembrane Space:- between inner and outer membranes of mitochondrionOxidative Phosphorylation:- a) electron transport chain uses electrons to pump H+ into space between mitochondrial membranes- different pumps- b) ATP synthase uses diffusion of H+ back across membrane to make ATPElectron Transport Chain:- series of H+ pumps in inner membrane using energy from electrons- slightly lower energy of electrons as they move from complex to complex- oxygen is last electron acceptor - desperate for electrons- converts into water after complex 4 (lowest energy electrons)- that's why you breathe (bring in oxygen to pump protons)- pumps bind and use electrons with different energies, pass electrons from one to another (chain)- electrons from electron carriers NADH or FADH2- electrons donated to O2, making H2O- pH is going down as wellElectrons in chain often carried by metal atoms:- iron or copper ions, surrounded by protein- iron-containing heme, similar to heme that carries O2 in bloodMitochondrial ATP synthase is a turbine:- H+ diffusion through channel spins channel proteins, catalyzes synthesis of ATP- facilitated diffusion from inner membrane space back into matrix- seeing ATP synthase spin, attach long fluorescent microfilament to rod2 steps of oxidative phosphorylation:- 1) Electron transport chain uses electrons to pump H+ into space between mitochondrial matrix- 2) ATP synthase uses diffusion of H+ back across membrane to make ATP- chemiosmosis - chemical flow of ion across membrane that isn't water (chemical instead)How efficient is it?:- per glucose: glycolysis (2 ATP), Krebs (2 ATP), oxidative phosphorylation (28-34 ATP?)- total: 32-38 ATP- not a fixed number- about 40% efficient (gasoline engine = 25 -
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