ATP. Division Ave. High School AP Biology. Cellular Respiration Stage 1: Glycolysis. The point is to make ATP! Glycolysis. What s the point?

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1 Division Ave. High School Celllar Respiration Stage 1: Glycolysis What s the point? The point is to make! Glycolysis Breaking down glcose glyco lysis (splitting sgar) glcose pyrvate x 6C In the cytosol? Why does that make evoltionary sense? ancient pathway which harvests energy where energy transfer first evolved transfer energy from organic molecles to still is starting point for ALL celllar respiration bt it s inefficient occrs in cytosol generate only for every 1 glcose That s not enogh for me! 1

2 Evoltionary perspective rokaryotes first cells had no organelles Anaerobic atmosphere life on Earth first evolved withot free oxygen ( ) in atmosphere energy had to be captred from organic molecles in absence of rokaryotes that evolved glycolysis are ancestors of all modern life ALL cells still tilize glycolysis Enzymes of glycolysis are well-conserved Yo mean we re related? Do I have to invite them over for the holidays? verview 10 reactions convert glcose (6C) to pyrvate () prodces: 4 & consmes: net yield: & DHA = dihydroxyacetone phosphate G3 = glyceraldehyde-3-phosphate glcose C-C-C-C-C-C frctose-1,6b -C-C-C-C-C-C- DHA -C-C-C G3 C-C-C- H i i pyrvate C-C-C 4 4 Glycolysis smmary ENERGY INVESTMENT endergonic invest some - ENERGY AYFF G3 C-C-C- 4 exergonic harvest a little & a little like $$ in the bank NET YIELD net yield ü ü

3 1st half of glycolysis (5 reactions) Glcose priming get glcose ready to split phosphorylate glcose moleclar rearrangement split destabilized glcose C H Glcose 1 hexokinase Glcose 6-phosphate phosphoglcose isomerase Frctose 6-phosphate 3 phosphofrctokinase Frctose 1,6-bisphosphate 4,5 aldolase isomerase Dihydroxyacetone phosphate Glyceraldehyde 3 -phosphate (G3) 6 i i glyceraldehyde 3-phosphate dehydrogenase 1,3-Bisphosphoglycerate 1,3-Bisphosphoglycerate (BG) (BG) H H C CHH CHH H nd half of glycolysis (5 reactions) Energy Harvest prodction G3 donates H oxidizes the sgar redces prodction G3 pyrvate E sgar donates w sbstrate level phosphorylation ayola! Finally some! 3-hosphoglycerate (3G) -hosphoglycerate (G) H 7 phosphoglycerate kinase 8 phosphoglyceromtase 9 enolase hosphoenolpyrvate (E) DHA -C-C-C i 6 10 pyrvate kinase G3 C-C-C- i 3-hosphoglycerate (3G) -hosphoglycerate (G) hosphoenolpyrvate (E) H - C CHH - C H C H - C C - C C CH 3 Sbstrate-level hosphorylation In the last steps of glycolysis, where did the come from to make? the sgar sbstrate (E) is transferred from E to ükinase ü H 9 enolase hosphoenolpyrvate (E) 10 pyrvate kinase hosphoenolpyrvate (E) H - C C - C C CH 3 I get it! The i came directly from the sbstrate! 3

4 Energy acconting of glycolysis glcose pyrvate 6C x 4 4 Bt glcose has Net gain = + some energy investment (- ) small energy retrn (4 + ) 1 6C sgar sgars so mch more to give! All that work! And that s all I get? Is that all there is? Not a lot of energy for 1 billon years + this is how life on Earth srvived no = slow growth, slow reprodction only harvest 3.5% of energy stored in glcose w more carbons to strip off = more energy to harvest glcose pyrvate 6C x Hard way to make a living! Bt can t stop there! DHA G3 raw materials prodcts i + i 6 1,3-BG i i 1,3-BG + Glycolysis 7 3-hosphoglycerate (3G) 8 3-hosphoglycerate (3G) glcose + + i + pyrvate + + Going to rn ot of withot regenerating, energy prodction wold stop! another molecle mst accept H from so is freed p for another rond -hosphoglycerate (G) H hosphoenolpyrvate (E) hosphoglycerate (G) hosphoenolpyrvate (E) H 4

5 How is recycled to? Another molecle mst accept H from H with oxygen aerobic respiration pyrvate withot oxygen anaerobic respiration fermentation C recycle who yo are which path yo se depends on acetyl-coa Krebs cycle lactate lactic acid fermentation acetaldehyde ethanol alcohol fermentation Fermentation (anaerobic) Bacteria, yeast pyrvate ethanol + C C 1C beer, wine, bread back to glycolysis Animals, some fngi pyrvate lactic acid back to glycolysis cheese, anaerobic exercise (no ) Alcohol Fermentation pyrvate ethanol + C C 1C back to glycolysis Dead end process at ~1% ethanol, kills yeast can t reverse the reaction bacteria yeast recycle Cont the carbons! 5

6 Lactic Acid Fermentation pyrvate lactic acid back to glycolysis Reversible process once is available, lactate is converted back to pyrvate by the liver animals some fngi recycle Cont the carbons! is a branching point fermentation anaerobic respiration mitochondria Krebs cycle aerobic respiration What s the point? The point is to make!

7 And how do we do that? synthase set p a gradient allow to flow throgh synthase powers bonding of i to + + i Bt Have we done that yet? N! There s still more to my story! Any Qestions?