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ATP

Making energy!. ATP. The point is to make ATP !. Discussion. What is the fundamental coupled reaction that makes up cellular respiration?. The energy needs of life. Organisms are endergonic systems Humans require ~2000 kilocalories per day What do we need energy for? synthesis

madaline-berger
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ATP

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  1. Making energy! ATP The pointis to makeATP!

  2. Discussion • What is the fundamental coupled reaction that makes up cellular respiration?

  3. The energy needs of life • Organisms are endergonic systems • Humans require ~2000 kilocalories per day • What do we need energy for? • synthesis • building biomolecules • reproduction • movement • active transport • temperature regulation

  4. Where do we get the energy from? • Work of life is done by energy coupling • use exergonic (catabolic) reactions to fuel endergonic (anabolic) reactions digestion energy + + synthesis energy + +

  5. Living economy • Fueling the body’s economy • eat high energy organic molecules • food = carbohydrates, lipids, proteins, nucleic acids • break them down • digest=catabolism • capture released energy in a form the cell can use • Need an energy currency • a way to pass energy around • need a short term energy storage molecule ATP

  6. O– O– O– O– P P P P –O O– –O O– –O –O O– O– O O O O Recall ATP… • ATP  ADP • releases energy • ∆G = -7.3 kcal/mole • Fuel other reactions • Phosphorylation • released Pi can transfer to other molecules • destabilizing the other molecules • enzyme that phosphorylates = “kinase” 7.3energy + ADP ATP

  7. enzyme + + H H H H H H H H H2O C C C C C C C C OH OH HO HO O O + H ATP ADP + C H H P HO OH H C C + + Pi C P An example of Phosphorylation: dehydration synthesis • Building polymers from monomers • need to destabilize the monomers, H2O doesn’t just come off on its own • phosphorylate! synthesis +4.2 kcal/mol “kinase”enzyme -7.3 kcal/mol -3.1 kcal/mol

  8. P ATP C 2 hexokinase C 2 ADP phosphofructokinase H C P Another example of Phosphorylation… • The first steps of cellular respiration • starting the breakdown of glucose requires some ATP investment glucose C-C-C-C-C-C fructose-1,6bP P-C-C-C-C-C-C-P DHAP P-C-C-C G3P C-C-C-P activationenergy

  9. H+ H+ H+ H+ H+ H+ H+ H+ rotor rod + P catalytic head H+ Our end goal… • ATP Synthase, enzyme channel in mitochondrial membrane • permeable to H+ • H+ flow down concentration gradient • flow like water over water wheel • flowing H+ cause change in shape of ATP synthase enzyme • powers bonding of Pi to ADP:ADP + Pi ATP ADP ATP

  10. Cellular RespirationHarvesting Chemical Energy ATP

  11. Harvesting stored energy • Energy is stored in organic molecules • carbohydrates, fats, proteins • Heterotrophs eat these organic molecules  food • Catabolize/digest organic molecules to get… • raw materials for synthesis • fuels for energy • controlled release of energy • “burning” fuels in a series of step-by-step enzyme-controlled reactions

  12. + + oxidation reduction e- How do we harvest energy from fuels? • Digest large molecules into smaller ones • break bonds & move electrons from one molecule to another • as electrons move they “carry energy” with them • that energy is stored in another bond, released as heat or harvested to make ATP loses e- gains e- oxidized reduced + – e- e- redox

  13. oxidation  C6H12O6 + 6O2 6CO2 + 6H2O + ATP reduction Coupling oxidation & reduction • REDOX reactions in respiration • release energy as breakdown organic molecules • break C-C bonds • strip off electrons from C-H bonds by removing H atoms • C6H12O6CO2 =thefuel has been oxidized • electrons attracted to more electronegative atoms • O2H2O =oxygen has been reduced • couple REDOX reactions & use the released energy to synthesize ATP O2

  14. like $$in the bank O– O– O– O– P P P P –O –O –O –O O– O– O– O– O O O O NAD+ nicotinamide Vitamin B3 niacin O O H H C C NH2 C C NH2 N+ N+ reduction + H oxidation phosphates adenine ribose sugar Moving electrons in respiration • Electron carriers move electrons by shuttling H atoms around • NAD+NADH (reduced) • FAD+2FADH2 (reduced) reducing power! NADH H carries electrons as a reduced molecule

  15. C6H12O6 + 6O2 ATP + 6H2O + 6CO2 Overview of cellular respiration • 4 metabolic stages • Anaerobic respiration 1. Glycolysis • respiration without O2 • in cytosol • Aerobic respiration • respiration using O2 • in mitochondria 2. Pyruvate oxidation 3. Krebs cycle 4. Electron transport chain ->ATP Synthase (+ heat)

  16. Cellular RespirationStage 1:Glycolysis

  17. glucose      pyruvate 6C 3C 2x Glycolysis • Breaking down glucose • “glyco – lysis” (splitting sugar) • ancient pathway which harvests energy • where energy transfer first evolved • transfer energy from organic molecules to ATP • still is starting point for ALL cellular respiration • but it’s inefficient • generate only2 ATP for every 1 glucose • Anaerobic, occurs in cytosol That’s not enoughATP for me!

  18. Discussion • Why does it make evolutionary sense that the earliest of the energy-releasing processes is glycolysis, which takes place in the cytosol?

  19. Evolutionary perspective • Prokaryotes • first cells had no organelles • Anaerobic atmosphere • life on Earth first evolved withoutfree oxygen (O2) in atmosphere • energy had to be captured from organic molecules in absence of O2 • Prokaryotes that evolved glycolysis are ancestors of all modern life • ALL cells still utilize glycolysis, nearly identical enzymes. Highly conserved!

  20. enzyme enzyme enzyme enzyme enzyme enzyme enzyme enzyme ATP ATP 4 2 4 2 2 ADP NAD+ ADP 2Pi 2 2H 2Pi glucose C-C-C-C-C-C Overview 10 reactions • convert glucose (6C)to 2 pyruvate (3C) • produces:+4 ATP & +2 NADH • consumes:-2 ATP • net yield:2 pyruvate, 2 ATP & 2 NADH fructose-1,6bP P-C-C-C-C-C-C-P DHAP P-C-C-C G3P C-C-C-P pyruvate C-C-C DHAP = dihydroxyacetone phosphate G3P = glyceraldehyde-3-phosphate

  21. Glycolysis summary endergonic invest some ATP ENERGY INVESTMENT -2 ATP G3P C-C-C-P exergonic harvest a little ATP & a little NADH ENERGY PAYOFF 4 ATP like $$in the bank • net yield • 2 ATP • 2 NADH NET YIELD

  22. O2 O2 O2 O2 O2 3C 2x Is that all there is? • Not a lot of energy… • for 1 billon years+ this is how life on Earth survived • no O2 = slow growth, slow reproduction • only harvest 3.5% of energy stored in glucose • more carbons to strip off = more energy to harvest glucose     pyruvate 6C

  23. DHAP G3P NAD+ Pi NAD+ Pi NADH NADH 1,3-BPG 1,3-BPG Pi Pi NAD+ NAD+ 6 NADH NADH 7 ADP ADP ATP ATP 3-Phosphoglycerate (3PG) 3-Phosphoglycerate (3PG) 8 2-Phosphoglycerate (2PG) 2-Phosphoglycerate (2PG) 9 H2O H2O Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) 10 ADP ADP ATP ATP Pyruvate Pyruvate But can’t stop there! • Going to run out of NAD+ • without regenerating NAD+,energy production would stop! • another molecule must accept H from NADH • so NAD+ is freed up for another round raw materialsproducts Glycolysis glucose + 2ADP + 2Pi + 2 NAD+2pyruvate+2ATP+2NADH

  24. recycleNADH How is NADH recycled to NAD+? without oxygen anaerobic respiration “fermentation” with oxygen aerobic respiration Another molecule must accept H from NADH pyruvate NAD+ H2O CO2 NADH NADH O2 acetaldehyde NADH acetyl-CoA NAD+ NAD+ lactate lactic acidfermentation which path you use depends on who you are… Krebs cycle ethanol alcoholfermentation

  25. O2 O2 Pyruvate is a branching point Pyruvate fermentation anaerobicrespiration mitochondria Krebs cycle aerobic respiration

  26. pyruvate  ethanol + CO2 3C 2C 1C pyruvate  lactic acid NADH NADH NAD+ NAD+ 3C 3C Fermentation (anaerobic) • Yeast, fungi back to glycolysis • beer, wine, bread • Animals, some bacteria back to glycolysis • cheese, anaerobic exercise (no O2)

  27. pyruvate  ethanol + CO2 3C 2C 1C NADH NAD+ recycleNADH Yeast Fungi Alcohol Fermentation back to glycolysis • Dead end process • at ~12% ethanol, kills yeast • can’t reverse the reaction

  28. O2 pyruvate  lactic acid NADH NAD+ 3C 3C recycleNADH animalsbacteria Lactic Acid Fermentation  back to glycolysis • Reversible process • once O2 is available, lactate is converted back to pyruvate by the liver • Why would this be reversible but not alcoholic ferm.? (Hint: C)

  29. Discussion • Knowing what you do about glucose catabolism so far, how can we use bacteria and yeast to… • Make bread rise? • Make alcoholic drinks? • If you want to make bread or an alcoholic drink, what should the bacteria or yeast environment contain? What should it not contain?

  30. Cellular RespirationStage 2 & 3: Oxidation of Pyruvate Krebs Cycle

  31. outer membrane intermembrane space inner membrane cristae matrix mitochondrialDNA Mitochondria — Structure • Double membrane energy harvesting organelle • smooth outer membrane • highly folded inner membrane • cristae • intermembrane space • fluid-filled space between membranes • matrix • inner fluid-filled space • prokaryotic DNA (mDNA), ribosomes • enzymes • free in matrix & membrane-bound What cells would have a lot of mitochondria?

  32. Oooooh!Form fits function! Mitochondria – Function Membrane-bound proteins: Enzymes & permeases (membrane transport proteins) Advantage of highly folded inner membrane? More surface area for membrane-bound enzymes & permeases

  33. Discussion • Thinking of the human body, which kinds of cells would you expect would have more mitochondria? Which would you expect would have less? (If you’ve learned this in anatomy, be nice, give your partner a chance to try their hand at it first :P)

  34. glucose      pyruvate 6C 3C 2x pyruvate       CO2 Glycolysis is only the start • Glycolysis • Pyruvate has more energy to yield • 3 more C to strip off (to oxidize) • if O2 is available, pyruvate enters mitochondria • enzymes of Krebs cycle complete the full oxidation of sugar to CO2 3C 1C

  35. Cellular respiration

  36. [ ] 2x pyruvate  acetyl CoA + CO2 NAD Oxidation of pyruvate • Pyruvate enters mitochondrial matrix • Pyruvate is oxidized • releases 2 CO2(count the carbons!) • reduces 2NAD  2 NADH (moves e-) • produces 2 (two-carbon) acetyl CoA • Acetyl CoA enters Krebs cycle 1C 3C 2C

  37. NAD+ 2 x [ ] Pyruvate oxidized to Acetyl CoA reduction Acetyl CoA Coenzyme A CO2 Pyruvate C-C C-C-C oxidation Yield = 2C sugar + NADH + CO2

  38. 1937 | 1953 Krebs cycle • aka Citric Acid Cycle • in mitochondrial matrix • 8 step pathway • each catalyzed by specific enzyme • step-wise catabolism of 6C citrate molecule • Evolved later than glycolysis • Evolutionarily… • bacteria 3.5 billion years ago (glycolysis) • free O22.7 billion years ago (photosynthesis) • eukaryotes 1.5 billion years ago (aerobic respiration = organelles  mitochondria) Hans Krebs 1900-1981

  39. 2C 6C 5C 4C 3C 4C 4C 4C 4C 6C CO2 CO2 Count the carbons! pyruvate acetyl CoA citrate oxidationof sugars This happens twice for each glucose molecule, because glycolysis produced two pyruvates x2

  40. 2C 6C 5C 4C 3C 4C 6C 4C 4C 4C NADH ATP CO2 CO2 CO2 NADH NADH FADH2 NADH Count the electron carriers! pyruvate acetyl CoA citrate reductionof electroncarriers x2

  41. What happened? So we fully oxidized glucose C6H12O6  CO2 & ended up with 4 ATP! What’s the point? :/

  42. http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cycle_works__quiz_1_.htmlhttp://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cycle_works__quiz_1_.html H+ H+ H+ H+ H+ H+ H+ H+ H+ Electron Carriers = Hydrogen Carriers • Krebs cycle produces large quantities of electron carriers • NADH • FADH2 • go to Electron Transport Chain! ADP+ Pi ATP

  43. Discussion • Krebs Cycle and Glycolysis have given us energy carriers NADH, FADH2… • …which will go to the electron transport chain… • …where ATP synthase is located… • PREDICT… how will we be able to use NADH and FADH2 to make ATP??

  44. 4 NAD+1 FAD 4 NADH+1FADH2 2x 1C 3x 1 ADP 1 ATP Energy accounting of Krebs cycle Net gain = 2 ATP = 8 NADH + 2 FADH2 pyruvate          CO2 3C ATP

  45. Cellular RespirationStage 4: Electron Transport Chain

  46. Cellular respiration

  47. ATP accounting so far… • Glycolysis 2ATP • Kreb’s cycle 2ATP • Life takes a lot of energy to run, need to extract more energy than 4 ATP! There’s got to be a better way! I need a lotmore ATP! A working muscle recycles over 10 million ATPs per second

  48. O2 There is a better way! • Electron Transport Chain • series of proteins built into inner mitochondrial membrane • along cristae • transport proteins& enzymes • transport of electrons down ETC linked to pumping of H+ to create H+ gradient • yields ~36 ATP from 1 glucose! • only in presence of O2 (aerobic respiration) Thatsounds morelike it!

  49. Remember: Mitochondria • Double membrane • outer membrane • inner membrane • highly folded cristae • enzymes & transport proteins • Matrix space within the inner membrane • intermembrane space • fluid-filled space between membranes

  50. Innermitochondrialmembrane Outer mitochondrial membrane Electron Transport Chain Intermembrane space C Q cytochromebc complex cytochrome coxidase complex NADH dehydrogenase Mitochondrial matrix

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