1 / 27

Ch 9 (Part 3): 9.4 - E.T.C./ Oxidative Phosphorylation

Ch 9 (Part 3): 9.4 - E.T.C./ Oxidative Phosphorylation. ● So far, in glycolysis & the Krebs cycle, 1 glucose molecule has resulted in:  4 ATPs (2 from glycolysis, 2 from Krebs)  10 NADH (2 from gly., 2 from acetyl-CoA step, 6 from Krebs Cycle)  2 FADH 2 (from Krebs Cycle). x2.

cyma
Download Presentation

Ch 9 (Part 3): 9.4 - E.T.C./ Oxidative Phosphorylation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ch 9 (Part 3): 9.4 - E.T.C./ Oxidative Phosphorylation

  2. ● So far, in glycolysis & the Krebs cycle, 1 glucose molecule has resulted in:  4 ATPs (2 from glycolysis, 2 from Krebs)  10 NADH (2 from gly., 2 from acetyl-CoA step, 6 from Krebs Cycle)  2 FADH2 (from Krebs Cycle) x2

  3. ● Following glycolysis and the Krebs cycle, NADH and FADH2 account for most of the energy extracted from food ● These two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation

  4. ELECTRON TRANSPORT CHAIN (E.T.C.) ● E.T.C. = a collection of molecules (mostly protein complexes) embedded in the inner membrane of mitochondrion (foldings of inner membrane form CRISTAE)

  5. The Pathway of Electron Transport ● the groups along the chain alternate between reduced & oxidized states as they accept and donate electrons ● each successive group is more electronegative than the group before it, so the electrons are “pulled downhill” towards OXYGEN (the final electron carrier!)

  6. NADH 50 FADH2 Multiprotein complexes I FAD 40 FMN II Fe•S Fe•S Q III Cyt b Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle Glycolysis Fe•S 30 Cyt c1 IV Free energy (G) relative to O2 (kcal/mol) Cyt c ATP ATP ATP Cyt a Cyt a3 20 10 2 H+ + 1/2 O2 0 H2O

  7. ● as molecular oxygen (O2) is reduced, it also picks up H+ from the environment to form water (H2O)

  8. ATP Production of the E.T.C. Typically, the ATP produced is as follows: 1 NADH  3 ATP 1 FADH2 2 ATP (FADH2 is “dropped off” at a lower point in the E.T.C., so it generates fewer ATPs) “exchange rate”

  9. Chemiosmosis: The Energy-Coupling Mechanism ● Electron transfer in the electron transport chain causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space (active transport) ● H+ (protons) then move back across the membrane, passing through channels in ATP synthase

  10. Chemiosmosis: The Energy-Coupling Mechanism ● ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ATP ● This is an example of CHEMIOSMOSIS, the use of energy in a H+ gradient to drive cellular work

  11. ● The energy stored in a H+ gradient across a membrane couples the redox reactions of the electron transport chain to ATP synthesis ● The H+ gradient is referred to as a PROTON-MOTIVE FORCE, emphasizing its capacity to do work

  12. (inner matrix) ● protons then diffuse back across the membrane through the ATP synthase complex which causes the phosphorylation of ADP to form ATP! (intermembrane space)

  13. INTERMEMBRANE SPACE A rotor within the membrane spins as shown when H+ flows past it down the H+ gradient. H+ H+ H+ H+ H+ H+ H+ A stator anchored in the membrane holds the knob stationary. A rod (or “stalk”) extending into the knob also spins, activating catalytic sites in the knob. H+ Three catalytic sites in the stationary knob join inorganic phosphate to ADP to make ATP. ADP + ATP P i MITOCHONDRAL MATRIX

  14. Inner mitochondrial membrane Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle Glycolysis ATP ATP ATP H+ H+ H+ H+ Cyt c Protein complex of electron carriers Intermembrane space Q IV III I ATP synthase II Inner mitochondrial membrane H2O 2H+ + 1/2 O2 FADH2 FAD NAD+ NADH + H+ ATP ADP + P i (carrying electrons from food) H+ Mitochondrial matrix Electron transport chain Electron transport and pumping of protons (H+), Which create an H+ gradient across the membrane Chemiosmosis ATP synthesis powered by the flow of H+ back across the membrane Oxidative phosphorylation

  15. ELECTRON TRANSPORT CHAIN ANIMATION!

  16. SUMMARY: ● most energy flows in this sequence: Glucose  NADH  E.T.C.  proton  ATP motive force

  17. PROCESS ATP produced by subs. phos. Reduced coenz. ATP produced by oxid. phos. (in the E.T.C.) TOTAL ATPs Glycolysis 2 ATP 2 NADH (go to ETC) 4-6 ATP 6-8 oxid. of pyruvate to acetyl CoA 2 NADH (go to ETC) 6 ATP 6 Krebs cycle 2 ATP 6 NADH 2 FADH2 (go to ETC) 18 ATP 4 ATP 24 TOTAL ATPs 36-38!

  18. ● approximately 40% of energy in glucose is converted to ATP ●the remaining energy is lost as heat

  19. Electron shuttles span membrane MITOCHONDRION CYTOSOL 2 NADH or 2 FADH2 2 NADH 2 NADH 6 NADH 2 FADH2 Oxidative phosphorylation: electron transport and chemiosmosis Glycolysis 2 Acetyl CoA Citric acid cycle 2 Pyruvate Glucose + 2 ATP + 2 ATP + about 32 or 34 ATP by substrate-level phosphorylation by substrate-level phosphorylation by oxidation phosphorylation, depending on which shuttle transports electrons form NADH in cytosol About 36 or 38 ATP Maximum per glucose: **actual ATP total’s are slightly less – when we factor in “real” exchange rates and the energetic cost of moving the ATP formed in the mitochondrion out into the cytosol, where it will be used**

More Related