2. AP Biology AP Biology John D. O’Bryant School of Mathematics and Science October 26, 2012

3. AP Biology Agenda  Do Now: Directions for tomorrow’s study session, room assignments; HW Review  Case Study: A Rigorous Investigation  Quiz  Cellular Respiration Lab: Respirometer Lab  Cellular Respiration Lab: Yeast Fermentation  Cellular Respiration: Lecture/Discussion

4. AP Biology HW discussion  1. The citric acid cycle does not require oxygen. Why does cellular respiration stop in the absence of oxygen?

5. AP Biology HW discussion  2. Why can't cells store large quantities of ATP? Consider both the chemical stability and the cell's osmotic potential in your answer.

6. AP Biology HW discussion  3. Given that cells cannot store ATP for long periods of time, how do they store energy?

7. AP Biology HW discussion  4. Suppose it takes 1,000 g of glucose to grow 10 g of an anaerobic bacterium, how many grams of glucose would it take to grow 10 g of that same bacterium if it was respiring aerobically? (Hint: This is a ratio and proportion problem.)

8. AP Biology 2007-2008 Cellular Respiration Stage 1: Glycolysis

9. AP Biology 7 8 H2OH2O 9 10 ADP ATP 3-Phosphoglycerate (3PG) 3-Phosphoglycerate (3PG) 2-Phosphoglycerate (2PG) 2-Phosphoglycerate (2PG) Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) Pyruvate ADP ATP ADP ATP ADP ATP H2OH2O NAD + NADH NAD + NADH PiPi PiPi 6 Glycolysis glucose + 2ADP + 2P i + 2 NAD +  2 pyruvate + 2ATP + 2NADH 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 PiPi NAD + G3P 1,3-BPG NADH NAD + NADH PiPi DHAP raw materials  products

10. AP Biology NADH pyruvate acetyl-CoA lactate ethanol NAD + NADH NAD + NADH CO 2 acetaldehyde H2OH2O Krebs cycle O2O2 lactic acid fermentation with oxygen aerobic respiration without oxygen anaerobic respiration “fermentation” How is NADH recycled to NAD + ? Another molecule must accept H from NADH recycle NADH which path you use depends on who you are… alcohol fermentation

11. AP Biology Fermentation (anaerobic)  Bacteria, yeast 1C 3C2C pyruvate  ethanol + CO 2  Animals, some fungi pyruvate  lactic acid 3C  beer, wine, bread  cheese, anaerobic exercise (no O 2 ) NADHNAD + NADHNAD + back to glycolysis 

12. AP Biology recycle NADH Alcohol Fermentation 1C 3C2C pyruvate  ethanol + CO 2 NADHNAD + Count the carbons!  Dead end process  at ~12% ethanol, kills yeast  can’t reverse the reaction bacteria yeast back to glycolysis 

13. AP Biology recycle NADH  Reversible process  once O 2 is available, lactate is converted back to pyruvate by the liver Lactic Acid Fermentation pyruvate  lactic acid 3C NADHNAD +  Count the carbons! O2O2 animals some fungi back to glycolysis 

14. AP Biology Pyruvate is a branching point Pyruvate O2O2 O2O2 mitochondria Krebs cycle aerobic respiration fermentation anaerobic respiration

15. AP Biology 2006-2007 Cellular Respiration Stage 2 & 3: Oxidation of Pyruvate Krebs Cycle

16. AP Biology Cellular respiration

17. AP Biology 2006-2007 Cellular Respiration Stage 4: Electron Transport Chain

18. AP Biology Cellular respiration

19. AP Biology Electron Transport Chain Intermembrane space Mitochondrial matrix Q C NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex Inner mitochondrial membrane

20. AP Biology G3P Glycolysis Krebs cycle 8 NADH 2 FADH 2 Remember the Electron Carriers? 2 NADH Time to break open the piggybank! glucose

21. AP Biology Electron Transport Chain intermembrane space mitochondrial matrix inner mitochondrial membrane NAD + Q C NADH H 2 O H+H+ e–e– 2H + +O2O2 H+H+ H+H+ e–e– FADH 2 1212 NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex FAD e–e– H H  e- + H + NADH  NAD + + H H p e Building proton gradient! What powers the proton (H + ) pumps?…

22. AP Biology H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP NAD + Q C NADH H 2 O H+H+ e–e– 2H + +O2O2 H+H+ H+H+ e–e– FADH 2 1212 NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex FAD e–e– Stripping H from Electron Carriers  Electron carriers pass electrons & H + to ETC  H cleaved off NADH & FADH 2  electrons stripped from H atoms  H + (protons)  electrons passed from one electron carrier to next in mitochondrial membrane (ETC)  flowing electrons = energy to do work  transport proteins in membrane pump H + (protons) across inner membrane to intermembrane space ADP + P i TA-DA!! Moving electrons do the work! H+H+ H+H+ H+H+

23. AP Biology But what “pulls” the electrons down the ETC? electrons flow downhill to O 2 oxidative phosphorylation O2O2 H2OH2O

24. AP Biology Electrons flow downhill  Electrons move in steps from carrier to carrier downhill to oxygen  each carrier more electronegative  controlled oxidation  controlled release of energy make ATP instead of fire!

25. AP Biology H+H+ ADP + P i H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ We did it! ATP  Set up a H + gradient  Allow the protons to flow through ATP synthase  Synthesizes ATP ADP + P i  ATP Are we there yet? “proton-motive” force

26. AP Biology  The diffusion of ions across a membrane  build up of proton gradient just so H+ could flow through ATP synthase enzyme to build ATP Chemiosmosis Chemiosmosis links the Electron Transport Chain to ATP synthesis So that’s the point!

27. AP Biology Peter Mitchell  Proposed chemiosmotic hypothesis  revolutionary idea at the time 1961 | 1978 1920-1992 proton motive force

28. AP Biology H+H+ H+H+ O2O2 + Q C ATP Pyruvate from cytoplasm Electron transport system ATP synthase H2OH2O CO 2 Krebs cycle Intermembrane space Inner mitochondrial membrane 1. Electrons are harvested and carried to the transport system. 2. Electrons provide energy to pump protons across the membrane. 3. Oxygen joins with protons to form water. 2H + NADH Acetyl-CoA FADH 2 ATP 4. Protons diffuse back in down their concentration gradient, driving the synthesis of ATP. Mitochondrial matrix 2 1 H+H+ H+H+ O2O2 H+H+ e-e- e-e- e-e- e-e- ATP

29. AP Biology Cellular respiration 2 ATP ~36 ATP ++ ~40 ATP

30. AP Biology Summary of cellular respiration  Where did the glucose come from?  Where did the O 2 come from?  Where did the CO 2 come from?  Where did the CO 2 go?  Where did the H 2 O come from?  Where did the ATP come from?  What else is produced that is not listed in this equation?  Why do we breathe? C 6 H 12 O 6 6O 2 6CO 2 6H 2 O~40 ATP  +++

31. AP Biology  ETC backs up  nothing to pull electrons down chain  NADH & FADH 2 can’t unload H  ATP production ceases  cells run out of energy  and you die! Taking it beyond…  What is the final electron acceptor in Electron Transport Chain? O2O2  So what happens if O 2 unavailable? NAD + Q C NADH H 2 O H+H+ e–e– 2H + +O2O2 H+H+ H+H+ e–e– FADH 2 1212 NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex FAD e–e–

32. AP Biology 2006-2007 What’s the point? The point is to make ATP ! ATP

33. AP Biology Do Now (Quiz)  1. Which H+ ion has just passed through the inner mitochondrial membrane by diffusion?  A) hydrogen ion A  B) hydrogen ion B  C) hydrogen ion C  D) hydrogen ion D  E) hydrogen ion E

34. AP Biology Do Now (Quiz)  As a scientist employed by the FDA, you've been asked to sit on a panel to evaluate a pharmaceutical company's application for approval of a new weight loss drug called Fat Away. The company has submitted a report summarizing the results of their animal and human testing. In the report, it was noted that Fat Away works by affecting the electron transport chain. It decreases the synthesis of ATP by making the mitochondrial membrane permeable to H+ which allows H+ to leak from the mitochondrial matrix to the intermembrane space. This effect leads to weight loss.

35. AP Biology Do Now (Quiz)  2. Fat Away prevents ATP from being made by  A) blocking access of H+ to ATP synthetase.  B) glycolysis from occurring.  C) preventing the conversion of NADH to NAD+.  D) lowering body temperature.  E) slowing down the Krebs cycle.

36. AP Biology Do Now (Quiz)  3. To obtain energy from starch and glycogen, the body must begin by  A) hydrolyzing the starch to glucose and the glycogen to amino acids.  B) hydrolyzing both starch and glycogen to glucose.  C) converting both starch and glycogen to fatty acids.  D) removing nitrogen atoms from both molecules.  E) removing one glucose at a time with a condensation reaction.

37. AP Biology Do Now (Quiz) 4. Which of the following statements regarding glycolysis is false?  A) Glycolysis is considered to be an ancient metabolic system because it does not require oxygen.  B) Glycolysis is considered to be an ancient metabolic system because it is not located in a membrane-bound organelle.  C) Glycolysis is considered to be an ancient metabolic system because it occurs universally.  D) Glycolysis is considered to be an ancient metabolic system because it is the most efficient metabolic pathway for ATP synthesis.  E) Glycolysis is considered to be an ancient metabolic system because glucose is the universal substrate for glycolysis. 

38. AP Biology Do Now (Quiz)  5. A child is born with a rare disease in which mitochondria are missing from skeletal muscle cells. However, the muscles still function. Physicians find that  A) the muscles contain large amounts of lactate following even mild physical exercise.  B) the muscles contain large amounts of carbon dioxide following even mild physical exercise.  C) the muscles require extremely high levels of oxygen to function.  D) the muscle cells cannot split glucose to pyruvate.  E) the muscles require extremely large amounts of carbon dioxide to function. 

39. AP Biology Do Now (Quiz)  6. The function of the enzyme ATP synthase is to...  A) accept a proton from inside the cell membrane as it accepts electrons.  B) utilize the energy of the proton motive force to convert ADP to ATP.  C) produce reduced coenzymes like NADH.  D) transfer hydrogen to the electron transport chain.  E) shuttle electrons from NADH to a terminal electron acceptor.

40. AP Biology Do Now (Quiz)  7. Electrons enter the electron transport chain when NADH transfers them there along with protons in the form of hydrogen.   A) True  B) False

41. AP Biology Do Now (Quiz)  8. The electron transport chain consists of a series of membrane-bound carriers that shuttle protons and electrons to NADH.   A) True  B) False

42. AP Biology Lab: Alcoholic Fermentation in Yeast

43. AP Biology Lorenzo’s Oil