1 1 12/1/2015 Electron Transport Chain Filename: ETChain.ppt

2 2 12/1/2015 Lecture Outline Using Chemical energy to drive metabolism Production of ATP Cellular respiration –Clycolysis –Krebs cycle –Electron transport –Chemiosmosis

3 3 12/1/2015 Lecture Overview All organisms drive their metabolism with ATP generated from Rearrangement of chemical bonds Energetic electrons from proton pumps Electrons from photosynthesis Electrons from oxidation of sugars and fats

4 4 12/1/2015 Cellular Respiration Release of energy stored in organic compounds –Carbohydrate –Fats –Proteins (net energy loss) Oxygen is consumed as a reactant Carbon dioxide and water are byproducts Energy is used indirectly –trapped as ATP

5 5 12/1/2015 Pathways in Cellular Respiration Glycolysis Krebs cycle Electron transport chain Cellular Respiration Cumulative function of three metabolic pathways and chemiosmosis

6 6 12/1/2015 Catabolism of various foods

7 7 12/1/2015 Overview of Cellular Respiration A room of your own... ATP

8 8 12/1/2015 Electron Transport System

9 9 12/1/2015 Summary of Krebs Cycle IN Out

10 12/1/2015 Electron Transport Chain OCCURS in MITOCHONDRIAL INNER MEMBRANE or PROKARYTOIC CELL MEMBRANE linked to Glycolysis and Krebs cycle Electrons passed from NADH to oxygen Does not make ATP directly but through chemiosmosis Large Free energy drop ( 53 kcal/mol) is broken into a series of smaller steps that release energy in manageable amounts

Oxidation is the loss of electrons to any electron acceptor Although oxygen is the usual electron acceptor other electron acceptors include NAD+

12 12/1/2015 Reduction NADH Nicotinamide-adenine dinucleotide Oxidation NADH as an Electron Shuttle

13 12/1/2015 Electron Transport Chain

14 12/1/2015 ATP How ATP Drives Cellular Work ATP

15 12/1/ Ways to Produce ATP Substrate level phosphorylation –produces few molecules of ATP in aerobes (2 ATP from the respiration of 1 molecule of glucose) Proton motor force (chemiosmosis) –produces most of the ATP in aerobes (about 30 ATP from the complete respiration of glucose to CO 2 and H 2 O)

16 12/1/2015 Substrate Level Phosphorylation ATP Production more primitive method Examples: 2 steps in glycolysis where ADP + Substrate-P -> ATP + substrate Note that the phosphate comes from a phosphorylated substrate, not from Pi 2 ADP + Phosphoenolpyruvate -> pyruvate + 2 ATP

17 12/1/2015 Proton Motor Force ATP production ATP synthase/ FoF1 complex More advanced method Proton transport across a membrane with F o F 1 complex powers the following reaction:- ADP + P i -> ATP Note that the phosphate comes from P i (inorganic phosphate) This is the major ATP source for aerobic bacteria, mitochondria and chloroplasts

18 12/1/2015 ATP synthase/ F o F 1 complex requires: Membrane Gradient of H+ concentration across membrane (one side more acid than the other) Fo/Fi protein complex in membrane ADP + Pi

19 12/1/2015 FoF1 complex low pH H + H + H + H + H + H + H + H + H + H + ADP +Pi ATP Membrane Fo F1

20 12/1/2015 FoF1 complex H + H + ADP ATP H + +Pi H + H + Fo (3 subunits in bacteria) forms a proton channel F1 (9 protein subunits) carries ATP synthase

21 12/1/2015 Fo F1 Fo F1 Fo F1 FoF1 complexes under EM look like “lollipops”

22 12/1/2015 Fo F1 Shows only ATP’ase H + F1 Fo Shows proton transfer H + H + H + Dissociated FoF1

23 12/1/2015 Aerobic bacterium Chloroplast Mitochondrion stroma matrix thylakoid = acid region F O F 1 COMPLEXES

24 12/1/2015 How does the F o F 1 complex work? Fo F1 ? One hypothesis is that F1 rotates as it releases ATP’s Not known

25 12/1/2015 chemical energy proton motor force ATP Chemiosmosis

26 12/1/2015 Tally=2 Tally=0 Tally=2 Tally= ~36 Review