Electron Transport Chain

Electron Transport Chain

NADH and FADH2 are electron carriers Each H atom contains 1 electron These electrons are transferred to a series of components that are found in the inner mitochondrial membrane This is known as the Electron Transport Chain Introduction Electron Carrier Glycolysis Pyruvate OxidationKrebs Cycle G3P GlucosePyruvateGlucose Pyruvate Glucose NADHFADH2Therefore, before we enter the electron transport chain we have:10 NADH2 FADH2

111222360000The ETC is a series of proteins arranged as a chain on the cristae of the inner mitochondrial membrane

The components of the ETC are arranged in order of increasing electronegativity: starts with the weakest attractor of electrons and ends with the strongest

Complexes in the ETCNADH dehydrogenase (Complex I ) Ubiquinone (Co-enzyme Q) (Shuttle)Cytochrome b-c (Complex II)Cytochrome c (Shuttle)Cytochrome oxidase (Complex III)Electrons get passed from complex to complex like a baton handed from runner to runner in a relay race

NADH passes its electrons on to Complex I NADH dehydrogenaseFADH2 passes its electrons to Q (shuttle)

Proton Pumps Move protons (H+ ions) from the mitochondrial matrix into the intermembrane space Protons moving against the gradient (need energy to do this), the electrons moving through the complexes provide this energyA proton gradient is created and the energy powers the ATP synthase enzyme- an ATP pump called an ATPase

3 proton pumpsComplex I Complex IIComplex III

NADH passes its electrons on to Complex I NADH dehydrogenaseFADH2 passes its electrons to Q (shuttle)

How many protons get pumped for every NADH? 3

How many protons get pumped for every FADH2? 2

Final Electron AcceptorWhy do we need oxygen for cellular respiration?Oxygen has a strong attraction for electronsIt takes the two electrons from the final proton complex (III) (cyctochrome oxidase) and takes two protons from the matrix and forms water

2e- + 2H+ + O2 H2O

Chemiosmosis Protons accumulate in the intermembrane space of the mitochondria this creates an electrochemical gradient The protons want to move back in to mitochondrial matrix

H+ (proton) Intermembrane Space Mitochondrial Matrix ATP Synthase The protons cannot move through the phospholipid bilayer Therefore, they are forced to move through special proton channels associated with the enzyme ATP synthase (ATPase)Protons move through the ATPase complex and as a result the synthesis of ATP from ADP and P occur in the matrix

How many ATP are formed?Start off with 10 NADH:Each NADH pumps out 3 H+Each H+ makes one ATP molecule10 x 3 = 30 ATP are generated from NADH Start off with 2 FADH2 Each FADH2 pumps out 2 H+ 2 x 2 = 4 ATP are generated from FADH2

Therefore a total of 34 ATP are generated by the electron transport chain. Putting it all togetherThe Electron Transport Chain:creates a proton gradient through transporting electronscreates watercreates ATPregenerates electron carriers (NAD+ and FAD)