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

3. AP Biology 2007-2008 What’s the point? The point is to make ATP ! ATP

4. AP Biology Glycolysis glucose      pyruvate 2x2x 6C3C In the cytosol? Why does that make evolutionary sense? That’s not enough ATP for me!  Breaking down glucose  “glyco – lysis” (splitting sugar)  inefficient  generate only 2 ATP for every 1 glucose  occurs in cytosol

5. AP Biology Evolutionary perspective  Prokaryotes are ancestors of all modern life  no organelles (no mitochonria)  Anaerobic atmosphere  No free oxygen (O 2 ) in atmosphere  ALL cells still utilize glycolysis

6. AP Biology 10 reactions  convert glucose (6C) to 2 pyruvate (3C)  produces: 4 ATP & 2 NADH  consumes: 2 ATP  net yield: 2 ATP & 2 NADH glucose C-C-C-C-C-C fructose-1,6bP P-C-C-C-C-C-C-P P-C-C-CC-C-C-P pyruvate C-C-C Overview DHAP = dihydroxyacetone phosphate G3P = glyceraldehyde-3-phosphate ATP 2 ADP 2 ATP 4 ADP 4 NAD + 2 2Pi2Pi enzyme 2Pi2Pi 2H2H 2

7. AP Biology Glycolysis summary endergonic invest some ATP exergonic harvest a little ATP & a little NADH net yield 2 ATP 2 NADH 4 ATP ENERGY INVESTMENT ENERGY PAYOFF G3P C-C-C-P NET YIELD -2 ATP

8. AP Biology  http://www.youtube.com/watch?v=3GTj QTqUuOw&feature=related http://www.youtube.com/watch?v=3GTj QTqUuOw&feature=related  http://highered.mcgraw- hill.com/sites/007352543x/student_view 0/chapter8/how_glycolysis_works.html http://highered.mcgraw- hill.com/sites/007352543x/student_view 0/chapter8/how_glycolysis_works.html

9. AP Biology PiPi 3 6 4,5 ADP NAD + Glucose hexokinase phosphoglucose isomerase phosphofructokinase Glyceraldehyde 3 -phosphate (G3P) Dihydroxyacetone phosphate Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate isomerase glyceraldehyde 3-phosphate dehydrogenase aldolase 1,3-Bisphosphoglycerate (BPG) 1,3-Bisphosphoglycerate (BPG) 1 2 ATP ADP ATP NADH NAD + NADH PiPi CH 2 CO CH 2 OH PO CH 2 OP O CHOH C CH 2 OP O CHOH CH 2 OP O OP O P O H CH 2 OH O CH 2 P O O CH 2 OH P O 1st half of glycolysis (5 reactions) Glucose “priming”  get glucose ready to split  phosphorylate glucose  molecular rearrangement  split destabilized glucose

10. AP Biology Important enzyme Phosphofructokinase (PFK) in step “3” of glycolysis (second ATP is used) (Allosteric enzyme) Activated by ADP (speeds respiration when ATP is needed) Inhibited by ATP (slows respiration when ATP is in excess)

11. AP Biology 2nd half of glycolysis (5 reactions) 7 8 H2OH2O 9 10 ADP ATP 3-Phosphoglycerate (3PG) 3-Phosphoglycerate (3PG) 2-Phosphoglycerate (2PG) 2-Phosphoglycerate (2PG) Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) Pyruvate phosphoglycerate kinase phosphoglycero- mutase enolase pyruvate kinase ADP ATP ADP ATP ADP ATP H2OH2O CH 2 OH CH 3 CH 2 O-O- O C PH CHOH O-O- O-O- O-O- C C C C C C P P O O O O O O CH 2 NAD + NADH NAD + NADH Energy Harvest G3P C-C-C-P PiPi PiPi 6 DHAP P-C-C-C  NADH production  G3P donates H  NAD +  NADH  ATP production  G3P    pyruvate  PEP sugar donates P  “substrate level phosphorylation”  ADP  ATP

12. AP Biology Substrate-level Phosphorylation I get it! The P i came directly from the substrate! H2OH2O 9 10 Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) Pyruvate enolase pyruvate kinase ADP ATP ADP ATP H2OH2O CH 3 O-O- O C O-O- C C C P O O O CH 2  ATP is made directly from a “substrate”  The Substrate is phosphorylated, oxidized and ATP is made from ADP  The 4 ATP made in Glycolysis are made this way ATP

13. AP Biology Energy accounting of glycolysis  Net gain = 2 ATP + 2 NADH  1 6C sugar  2 3C sugars- (pyruvates) 2 ATP2 ADP 4 ADP glucose      pyruvate 2x2x 6C3C ATP 4 2 NAD + 2 But glucose has so much more to give!

14. AP Biology Is that all there is?  Not a lot of energy…  for 1 billon years + this is how life on Earth survived  no O 2 = slow growth, slow reproduction  only harvest 3.5% of energy stored in glucose  more carbons to strip off = more energy to harvest O2O2 O2O2 O2O2 O2O2 O2O2 glucose     pyruvate 6C 2x2x 3C

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

16. AP Biology Lactic Acid Fermentation(anaerobic)  C 3 H 4 O 3 C 3 H 6 O 3 Pyruvate Lactate Pyruvate is REDUCED to Lactate and NAD+ is regenerated so respiration can continue. This occurs in muscles in O 2 debt (when running hard) until the debt is repaid (when you slow down) NADH NAD+

17. AP Biology  There is no O 2. Therefore pyruvate cannot be oxidized. Instead, it is reduced by NADH. No more ATP can be made

18. AP Biology recycle NADH Alcohol Fermentation 1C 3C2C pyruvate  ethanol + CO 2 NADHNAD +  Dead end process  at ~12% ethanol, kills yeast bacteria yeast

19. 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

20. AP Biology Fermentation (anaerobic)  Bacteria, yeast 1C 3C2C pyruvate  ethanol + CO 2  Animals, some fungi pyruvate  lactic acid 3C  beer, wine, bread  Pyruvate is reduced to ethanol  anaerobic exercise (no O 2 )  Pyruvate is reduced to lactate NADHNAD + NADHNAD +