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Overview

Overview. 10 reactions convert glucose (6C) to 2 pyruvate (3C) produces: 4 ATP & 2 NADH consumes: 2 ATP net: 2 ATP & 2 NADH. DHAP = dihydroxyacetone phosphate G3P = glyceraldehyde-3-phosphate. Glycolysis summary . endergonic invest some ATP. ENERGY INVESTMENT. G3P C-C-C -P.

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Overview

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  1. Overview 10 reactions • convert glucose (6C)to 2 pyruvate (3C) • produces:4 ATP & 2 NADH • consumes:2 ATP • net:2 ATP & 2 NADH DHAP = dihydroxyacetone phosphate G3P = glyceraldehyde-3-phosphate

  2. Glycolysis summary endergonic invest some ATP ENERGY INVESTMENT G3P C-C-C-P exergonic harvest a little ATP & a little NADH ENERGY PAYOFF 4ATP like $$in the bank yield 2 ATP 2 NADH NET YIELD

  3. 1st half of glycolysis (5 reactions) CH2OH Glucose “priming” O Glucose 1 ATP hexokinase • get glucose ready to split • phosphorylate glucose • molecular rearrangement • split destabilized glucose ADP CH2 O P O Glucose 6-phosphate 2 phosphoglucose isomerase CH2 P O CH2OH O Fructose 6-phosphate 3 ATP phosphofructokinase P O CH2 CH2 O P O ADP Fructose 1,6-bisphosphate aldolase 4,5 H O CH2 P isomerase C O C O Dihydroxyacetone phosphate Glyceraldehyde 3 -phosphate (G3P) CHOH CH2OH CH2 O P NAD+ Pi NAD+ Pi 6 glyceraldehyde 3-phosphate dehydrogenase NADH NADH P O O CHOH 1,3-Bisphosphoglycerate (BPG) 1,3-Bisphosphoglycerate (BPG) CH2 O P

  4. 2nd half of glycolysis (5 reactions) G3P C-C-C-P Energy Harvest • NADH production • G3P donates H • Sugar (oxidized or reduced?) • NAD+ (oxidized or reduced) • 2NAD+ 2NADH • ATP production • G3P pyruvate • PEP sugar donates P • 2ADP 2 ATP Pi Pi NAD+ NAD+ 6 NADH NADH 7 ADP ADP O- phosphoglycerate kinase C ATP ATP CHOH 3-Phosphoglycerate (3PG) 3-Phosphoglycerate (3PG) CH2 P O 8 O- phosphoglyceromutase O C H C O P 2-Phosphoglycerate (2PG) 2-Phosphoglycerate (2PG) CH2OH O- 9 H2O H2O enolase C O O C P Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) CH2 O- 10 ADP ADP C O pyruvate kinase Payola!Finally some ATP! ATP ATP C O CH3 Pyruvate Pyruvate

  5. 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 I get it! The PO4 camedirectly fromthe substrate!

  6. 2 ATP 2 ADP 4 ADP ATP 4 Energy accounting of glycolysis • Net gain = 2 ATP • some energy investment (-2 ATP) • small energy return (+4 ATP) • 1 6C sugar 2 3C sugars glucose      pyruvate 6C 3C 2x All that work! And that’s all I get?

  7. 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!

  8. DHAP G3P NAD+ Pi NAD+ Pi NADH NADH 1,3-BPG 1,3-BPG recycleNADH We can’t stop there! • Going to run out of NAD+ • without regenerating NAD+, energy production would stop! • another molecule must accept H from NADH Glycolysis glucose + 2ADP + 2Pi + 2 NAD+2pyruvate+2ATP+2NADH

  9. recycleNADH How is NADH recycled to NAD+? with oxygen aerobic respiration without oxygen anaerobic respiration fermentation 1. Another molecule must accept H from NADH 3. Bacteria/Yeast 2. Animals pyruvate NAD+ H2O CO2 NADH NADH O2 acetaldehyde NADH acetyl-CoA NAD+ NAD+ lactate (lactic acid) which path you use depends on who you are… Krebs cycle ethanol

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

  11. pyruvate  ethanol + CO2 3C 2C 1C NADH NAD+ Alcohol Fermentation bacteria yeast • Dead end process • at ~12% ethanol, kills yeast • can’t reverse the reaction Count thecarbons!

  12. O2 pyruvate  lactic acid NADH NAD+ 3C 3C Lactic Acid Fermentation animals  • Reversible process • once O2 is available, lactate is converted back to pyruvate by the liver Count thecarbons!

  13. O2 O2 Pyruvate is a branching point Pyruvate fermentation anaerobicrespiration mitochondria Kreb’s cycle aerobic respiration

  14. H+ H+ H+ H+ H+ H+ H+ H+ + P H+ And how do we do that? • ATP synthase • set up a H+ gradient • allow H+ to flow through ATP synthase • powers bonding of Pi to ADP ADP + PiATP ADP ATP But… Have we done that yet?

  15. ATP ATP 2 4 2 2 4 NAD+ ADP ADP 2Pi 2 2Pi 2H Overview glucose C-C-C-C-C-C 10 reactions • convert glucose (6C)to 2 pyruvate (3C) • produces:4 ATP & 2 NADH • consumes:2 ATP • net:2 ATP & 2 NADH fructose-1,6bP P-C-C-C-C-C-C-P DHAP P-C-C-C G3P C-C-C-P pyruvate C-C-C

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