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Unit 3 Topic 3

Unit 3 Topic 3. Cellular respiration. C 6 H 12 O 6 + 6O 2 --> 6CO 2 +6H 2 O. The Big Picture. Cellular respiration. Cellular Respiration Stage 1: Glycolysis. glucose      pyruvate. 6C. 3C. 2 x. Glycolysis. Breaking down glucose “ glyco – lysis ” (splitting sugar)

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Unit 3 Topic 3

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  1. Unit 3 Topic 3 Cellular respiration

  2. C6H12O6 + 6O2 --> 6CO2 +6H2O The Big Picture

  3. Cellular respiration

  4. Cellular RespirationStage 1:Glycolysis

  5. glucose      pyruvate 6C 3C 2x Glycolysis • Breaking down glucose • “glyco – lysis” (splitting sugar) • Occurs in the cytoplasm • A little ATP energy is harvested, • but it’s inefficient • generate only2 ATP for every 1 glucose That’s not enoughATP for me!

  6. Overview 10 reactions • convert glucose (6C)to 2 pyruvate (3C) • produces:4 ATP & 2 NADH • consumes:2 ATP • net yield:2 ATP & 2 NADH Substrate-level phosphorylation Substrate-level phosphorylation

  7. Products of glycolysis move on to stage 2

  8. Cellular RespirationStage 2: Pyruvate "grooming" & the Krebs Cycle

  9. Cellular respiration

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

  11. This happens twice for each glucose molecule

  12. 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

  13. Cellular RespirationStage 3: Electron Transport Chain

  14. Cellular respiration

  15. O2 ATP payoff! • Electron Transport Chain • series of proteins built into inner mitochondrial membrane • transport of electrons down ETC pumps H+ across the membrane to create H+ gradient • just like in the light reactions, the gradient powers ATP synthase

  16. Innermitochondrialmembrane Electron Transport Chain Intermembrane space C Q cytochrome cytochrome NADH dehydrogenase Mitochondrial matrix

  17. Remember the Electron Carriers? Krebs cycle Glycolysis 8 NADH 2 FADH2 2 NADH Time tobreak openthe piggybank!

  18. e p 1 2 Electron Transport Chain NADH  NAD+ + H intermembranespace H+ H+ H+ innermitochondrialmembrane H  e- + H+ C 2e– Q 2e– H 2e– FADH2 FAD H NADH 2H+ + O2 H2O NAD+ cytochrome cytochrome NADH dehydrogenase mitochondrialmatrix What powers the proton (H+) pumps?…

  19. H2O O2 Electronegativity! electronsare “pulled” to O2 oxidative phosphorylation

  20. ~38 ATP Cellular respiration + + 2 ATP 2 ATP 34 ATP

  21. C6H12O6 + 6CO2 + 6H2O + ~34-38 ATP 6O2 Summary of cellular respiration • Where did the glucose come from? • Where did the O2 come from? • Where did the CO2 come from? • Where did the CO2 go? • Where did the H2O come from? • Where did the ATP come from? • What is recycled for use again? • Why do we breathe?

  22. Taking it beyond… • What is the final electron acceptor in Electron Transport Chain? O2 • So what happens if O2 unavailable? • ETC backs up • nothing to pull electrons down chain • NADH & FADH2 can’t unload H • ATP production ceases • cells run out of energy

  23. Anaerobic respiration Making ATP without oxygen

  24. All cells carry out glycolysis: prokaryotes and eukaryotes. • Eukaryotes and many prokaryotes also carry out oxidative phosphorylation (remember this requires oxygen). How can some bacteria carry out aerobic respiration if they don't have mitochondria? FUN FACT: many bacteria have ETC’s in their cell membranes.

  25. A net of 2 ATP is generated in glycolysis. NAD+ must be present available for this process. For aerobic organisms this is not a problem, NAD+ is regenerated during oxidative phosphorylation (ETC). Fermentation is the pathway that some prokaryotes always have to take (obligate anaerobes). This pathway is also used by prokaryotes and yeasts that are facultative anaerobes. Fermentation is also used by your own muscles when you are working out strenuously and gas exchange is not happening fast enough to replenish ATP through oxidative phosphorylation.

  26. Fermentation (anaerobic) • Alcohol fermentation • Bacteria (prokaryotes), yeast (eukaryotes) • wine, bread • Lactic acid fermentation • Animals, some fungi (eukaryotes) • cheese, anaerobic exercise (no O2)

  27. recycleNADH Alcohol fermentation • NADH is recycled back to NAD+ when pyruvate is converted to ethanol. • Alcohol is released into the organism's environment as waste. • Fun fact: Bubbles in beer and champagne are CO2 released in the conversion of pyruvate to alcohol.

  28. recycleNADH • NADH is recycled back to NAD+ when pyruvate is converted to lactate (enzyme-catalyzed) • Once O2 is available, lactate is converted back to pyruvate by the liver • Cells can then resume aerobic respiration using pyruvate (starts Stage 2).

  29. Intermembrane space Pyruvate from cytoplasm Inner mitochondrial membrane H+ H+ Electron transport system C Q NADH e- H+ 2. Electrons provide energy to pump protons across the membrane. 1. Electrons are harvested and carried to the transport system. e- Acetyl-CoA NADH e- H2O e- Krebs cycle 3. Oxygen joins with protons to form water. 1 FADH2 O2 2 O2 + 2H+ H+ CO2 ATP H+ ATP ATP 4. Protons diffuse back indown their concentrationgradient, driving the synthesis of ATP. ATP synthase Mitochondrial matrix

  30. Catalyst: Answer all of the following questions in your notebook. • What are the products of pyruvate grooming for 1 molecule of glucose? • What are the products of the citric acid cycle for 1 molecule of glucose? • After glycolysis, pyruvate grooming, and the citric acid cycle, what are your net products? • What is phosphorylation? • What is substrate-level phosphorylation? • What is the main goal for stages 1-3?

  31. Catalyst: Answer all of the following questions in your notebook • What is the summary equation for cellular respiration? • If oxidation is a loss of electrons (in the form of hydrogen atoms) and reduction is the gain of electrons (in the form of hydrogen atoms), • what is oxidized during cellular respiration? • what is reduced during cellular respiration? • How does glucose get to your cells for cellular respiration? • What is the point of cellular respiration? • What are the net molecular products of glycolysis?

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