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ATP

Making energy!. ATP. The point is to make ATP !. Chemical energy. (a). First law of thermodynamics: Energy can be transferred or transformed but Neither created nor destroyed. For example, the chemical (potential) energy in food will be converted to the kinetic

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ATP

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  1. Making energy! ATP The pointis to makeATP!

  2. Chemical energy (a) First law of thermodynamics: Energy can be transferred or transformed but Neither created nor destroyed. For example, the chemical (potential) energy in food will be converted to the kinetic energy of the cheetah’s movement in (b). Figure 8.3  First Law Of Thermodynamics

  3. Heat co2 + H2O (b) Second law of thermodynamics: Every energy transfer or transformation increases the disorder (entropy) of the universe. For example, disorder is added to the cheetah’s surroundings in the form of heat and the small molecules that are the by-products of metabolism. Figure 8.3  Second Law

  4. Free Energy

  5. ∆G < 0 ∆G = 0 Reactions in a Closed System: What would happen To a living System if it were closed?

  6. ∆G < 0 Body Cells: What do we Need to Stay alive?

  7. The energy needs of life • Organisms are endergonic systems • What do we need energy for? • synthesis • building biomolecules • reproduction • movement • active transport • temperature regulation

  8. 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 + +

  9. high energy bonds ATP • Adenosine TriPhosphate • modified nucleotide • nucleotide =adenine + ribose + Pi AMP • AMP + Pi ADP • ADP + Pi ATP • adding phosphates is endergonic How efficient! Build once,use many ways

  10. O– O– O– O– O– O– O– O– P P P P P P P P –O –O –O O– O– O– –O –O –O O– O– O– –O –O O– O– O O O O O O O O I thinkhe’s a bitunstable…don’t you? How does ATP store energy? • Each negative PO4 more difficult to add ADP AMP ATP Instability of its P bonds makes ATP an excellent energy donor

  11. O– O– O– O– P P P P –O O– –O O– –O –O O– O– O O O O How does ATP transfer energy? • 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

  12. 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… • Building polymers from monomers • need to destabilize the monomers • phosphorylate! synthesis +4.2 kcal/mol “kinase”enzyme It’snever thatsimple! -7.3 kcal/mol -3.1 kcal/mol

  13. Cells spend a lot of time making ATP! Thepoint is to makeATP! What’s thepoint?

  14. How is ATP Made in a Cell? Substrate Level Phosphorylation

  15. Chemiosmosis Start with a mitochondrion or chloroplast Trap H+ in the intermembrane space

  16. Chemiosmosis Start with a mitochondrion or chloroplast Trap H+ in the intermembrane space How can this lead to ATP production?

  17. H+ H+ H+ H+ H+ H+ H+ H+ rotor rod + P catalytic head H+ 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 But… How is the proton (H+) gradient formed?

  18. That’s the rest of mystory! Any Questions?

  19. Cellular RespirationHarvesting Chemical Energy ATP

  20. What’s thepoint? The pointis to makeATP! ATP

  21. Harvesting stored energy • Energy is stored in organic molecules • carbohydrates, fats, proteins • Heterotrophs eat these organic molecules  food

  22. glucose + oxygen  energy + water + carbon dioxide respiration ATP + 6H2O + 6CO2 + heat  C6H12O6 + 6O2 COMBUSTION = making a lot of heat energy by burning fuels in one step ATP glucose O2 O2 fuel(carbohydrates) Which releases more Energy, combustion Of glucose or Cellular respiration? Harvesting stored energy RESPIRATION = making ATP (& some heat)by burning fuels in many small steps ATP enzymes CO2 + H2O + heat CO2 + H2O + ATP (+ heat)

  23. + + oxidation reduction e- How do we harvest energy from fuels? • Oxidation Reduction loses e- gains e- oxidized reduced + – e- e- redox

  24. e p loses e- gains e- oxidized reduced + – + + H oxidation reduction H  C6H12O6 + 6O2 6CO2 + 6H2O + ATP H How do we move electrons in biology? • Moving electrons in living systems • electrons cannot move alone in cells • electrons move as part of H atom • move H = move electrons oxidation reduction e-

  25. 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 How efficient! Build once,use many ways N+ N+ reduction + H oxidation phosphates adenine ribose sugar Moving electrons in respiration • Electron carriers move mighty electrons by shuttling H atoms around • NAD+NADH (reduced) • FAD+2FADH2 (reduced) reducing power! NADH H carries electrons as a reduced molecule

  26. 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 (+ heat)

  27. Cellular RespirationStage 1:Glycolysis

  28. glucose      pyruvate 6C 3C 2x Glycolysis • Breaking down glucose • “glyco – lysis” (splitting sugar) • but it’s inefficient • generate only2 ATP for every 1 glucose • still is starting point for ALL cellular respiration • occurs in cytosol In thecytosol?Why doesthat makeevolutionarysense? That’s not enough ATP for me

  29. Evolutionary perspective Enzymesof glycolysis are“well-conserved” • Prokaryotes • first cells had no organelles • Anaerobic atmosphere • life on Earth first evolved withoutfree oxygen (O2) in atmosphere • Prokaryotes that evolved glycolysis are ancestors of all modern life • ALL cells still utilize glycolysis You meanwe’re related?Do I have to invitethem over for the holidays?

  30. enzyme enzyme enzyme enzyme enzyme enzyme enzyme enzyme ATP ATP 4 2 2 4 2 ADP ADP NAD+ 2Pi 2 2Pi 2H glucose C-C-C-C-C-C Overview 10 reactions fructose-1,6bP P-C-C-C-C-C-C-P DHAP P-C-C-C G3P C-C-C-P What has more Free energy, G3P or pyruvate? pyruvate C-C-C

  31. 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

  32. O- 9 H2O H2O enolase C O O C P Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) CH2 O- 10 ADP ADP C O pyruvate kinase ATP ATP C O CH3 Pyruvate Pyruvate Substrate-level Phosphorylation • In the last steps of glycolysis, where did the P come from to make ATP? • the sugar substrate (PEP) • P is transferred from PEP to ADP • kinase enzyme • ADP  ATP ATP What sort of Enzyme does This?

  33. 2 ATP 2 ADP 2 NAD+ 4 ADP ATP 4 2 Energy accounting of glycolysis • Net gain = 2 ATP + 2 NADH • some energy investment (-2 ATP) • small energy return (4 ATP + 2 NADH) • 1 6C sugar 2 3C sugars glucose      pyruvate 6C 3C 2x The magic number is? Where is the Extra energy?

  34. 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 Hard wayto makea living!

  35. 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 What is the Oxidizing Agent of Glycolysis?

  36. recycleNADH How is NADH recycled to NAD+? without oxygen anaerobic respiration “fermentation” with oxygen aerobic respiration Another molecule must accept the mighty electrons from NADH pyruvate NAD+ H2O CO2 NADH NADH O2 acetaldehyde NADH acetyl-CoA NAD+ NAD+ What has more Free energy Pyruvate or Lactic acid? lactate lactic acidfermentation Krebs cycle ethanol alcoholfermentation

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

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

  39. What’s thepoint? The pointis to makeATP! ATP

  40. [ ] 2x pyruvate  acetyl CoA + CO2 NAD Oxidation of pyruvate • Pyruvate enters mitochondrial matrix • 3 step oxidation process • releases 2 CO2(count the carbons!) • reduces 2NAD  2 NADH (moves e-) • produces 2acetyl CoA • Acetyl CoA enters Krebs cycle 1C 3C 2C Wheredoes theCO2 go? Exhale!

  41. 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 • does that make evolutionary sense? • 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

  42. 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 x2

  43. 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 This happens twice for each glucose molecule x2

  44. Whassup? So we fully oxidized glucose C6H12O6  CO2 & ended up with 4 ATP! What’s the point?

  45. 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 What’s so important about electron carriers?

  46. 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

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