Oxidation refers to the loss of electrons to any electron acceptor, not just to oxygen. Uses exergonic flow of electrons through ETC to pump H+ across membrane.
Pumping H+ across membrane … what is energy to fuel that? Can’t be ATP! that would cost you what you want to make! Its like cutting off your leg to buy a new pair of shoes. :-( Flow of electrons powers pumping of H + O 2 is 2 oxygen atoms both looking for electrons
Electrons move from molecule to molecule until they combine with O & H ions to form H 2 O It’s like pumping water behind a dam -- if released, it can do work
Chemiosmosis is the diffusion of ions across a membrane. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane. Hydrogen ions (protons) will diffuse from an area of high proton concentration to an area of lower proton concentration. Peter Mitchell proposed that an electrochemical concentration gradient of protons across a membrane could be harnessed to make ATP. He likened this process to osmosis, the diffusion of water across a membrane, which is why it is called chemiosmosis.
Where did the glucose come from? from food eaten Where did the O 2 come from? breathed in Where did the CO 2 come from? oxidized carbons cleaved off of the sugars (Krebs Cycle) Where did the CO 2 go? exhaled Where did the H 2 O come from? from O 2 after it accepts electrons in ETC Where did the ATP come from? mostly from ETC What else is produced that is not listed in this equation? NAD, FAD, heat!
What if you have a chemical that punches holes in the inner mitochondrial membrane?
Cellular Respiration Stage 4: Electron Transport Chain
Electron Transport Chain Intermembrane space Mitochondrial matrix Q C NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex Inner mitochondrial membrane
Remember the Electron Carriers? G3P Glycolysis Krebs cycle 8 NADH 2 FADH 2 2 NADH Time to break open the piggybank ! glucose
Electron Transport Chain intermembrane space mitochondrial matrix inner mitochondrial membrane NAD + Q C NADH H 2 O H + e – 2H + + O 2 H + H + e – FADH 2 NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex FAD e – H H e- + H + NADH NAD + + H H Building proton gradient ! What powers the proton (H + ) pumps?… 1 2 p e
electrons passed from one electron carrier to next in mitochondrial membrane (ETC)
flowing electrons = energy to do work
transport proteins in membrane pump H + ( protons ) across inner membrane to intermembrane space
ATP ADP + P i TA-DA !! Moving electrons do the work ! H + H + H + H + H + H + H + H + H + H + H + H + NAD + Q C NADH H 2 O H + e – 2H + + O 2 H + H + e – FADH 2 1 2 NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex FAD e –
But what “pulls” the electrons down the ETC? electrons flow downhill to O 2 oxidative phosphorylation O 2 H 2 O
H + H + O 2 + Q C ATP Pyruvate from cytoplasm Electron transport system ATP synthase H 2 O CO 2 Krebs cycle Intermembrane space Inner mitochondrial membrane 1. Electrons are harvested and carried to the transport system. 2. Electrons provide energy to pump protons across the membrane. 3. Oxygen joins with protons to form water . 2H + NADH NADH Acetyl-CoA FADH 2 ATP 4. Protons diffuse back in down their concentration gradient, driving the synthesis of ATP . Mitochondrial matrix 2 1 H + H + O 2 H + e - e - e - e - ATP
Cellular respiration 2 ATP 2 ATP ~36 ATP + + ~40 ATP