Chapter 15 lecture 2

2007-2008 Cellular Respiration Stage 1: Glycolysis

2007-2008 What’s the point? The point is to make ATP ! ATP

Glycolysis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],In the cytosol? Why does that make evolutionary sense? That’s not enough ATP for me ! glucose      pyruvate 2 x 6C 3C

Evolutionary perspective ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],You mean we’re related? Do I have to invite them over for the holidays? Enzymes of glycolysis are “well-conserved”

[object Object],[object Object],[object Object],[object Object],[object Object],Overview glucose C-C-C-C-C-C 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 DHAP = dihydroxyacetone phosphate G3P = glyceraldehyde-3-phosphate ATP 2 ADP 2 ATP 4 ADP 4 NAD + 2 2 P i enzyme enzyme enzyme enzyme enzyme enzyme enzyme enzyme 2 P i 2 H 2

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

1st half of glycolysis (5 reactions) P i 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 P i CH 2 C O CH 2 OH P O CH 2 O P O CHOH C CH 2 O P O CHOH CH 2 O P O CH 2 O P O P O CH 2 H CH 2 OH O CH 2 P O O CH 2 OH P O Glucose “priming” ,[object Object],[object Object],[object Object],[object Object]

2nd half of glycolysis (5 reactions) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Payola ! Finally some ATP ! 7 8 H 2 O 9 10 ADP ATP 3-Phosphoglycerate (3PG) 3-Phosphoglycerate (3PG) 2-Phosphoglycerate (2PG) 2-Phosphoglycerate (2PG) Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) Pyruvate Pyruvate phosphoglycerate kinase phosphoglycero- mutase enolase pyruvate kinase ADP ATP ADP ATP ADP ATP H 2 O CH 2 OH CH 3 CH 2 O - O C P H CHOH 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 P i P i 6 DHAP P- C-C-C

Substrate-level Phosphorylation ,[object Object],[object Object],[object Object],[object Object],[object Object],I get it! The P i came directly from the substrate ! ATP H 2 O 9 10 Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) Pyruvate Pyruvate enolase pyruvate kinase ADP ATP ADP ATP H 2 O CH 3 O - O C O - C C C P O O O CH 2

Energy accounting of glycolysis ,[object Object],[object Object],[object Object],[object Object],glucose      pyruvate 2 x 6C 3C All that work! And that’s all I get? But glucose has so much more to give ! 2 ATP 2 ADP 4 ADP ATP 4 2 NAD + 2

Is that all there is? ,[object Object],[object Object],[object Object],[object Object],[object Object],Hard way to make a living ! glucose     pyruvate 6C O 2 O 2 O 2 O 2 O 2 2 x 3C

But can’t stop there ! ,[object Object],[object Object],[object Object],[object Object],Glycolysis glucose + 2ADP + 2P i + 2 NAD +  2 pyruvate + 2ATP + 2NADH raw materials  products 7 8 H 2 O 9 10 ADP ATP 3-Phosphoglycerate (3PG) 3-Phosphoglycerate (3PG) 2-Phosphoglycerate (2PG) 2-Phosphoglycerate (2PG) Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) Pyruvate Pyruvate ADP ATP ADP ATP ADP ATP H 2 O NAD + NADH NAD + NADH P i P i 6 P i NAD + G3P 1,3-BPG 1,3-BPG NADH NAD + NADH P i DHAP

How is NADH recycled to NAD + ? ,[object Object],NADH pyruvate acetyl-CoA lactate ethanol NAD + NAD + NADH NAD + NADH CO 2 acetaldehyde H 2 O Krebs cycle O 2 lactic acid fermentation with oxygen aerobic respiration without oxygen anaerobic respiration “ fermentation ” which path you use depends on who you are… alcohol fermentation recycle NADH

Fermentation (anaerobic) ,[object Object],[object Object],[object Object],[object Object],back to glycolysis  back to glycolysis  1C 3C 2C pyruvate  ethanol + CO 2 pyruvate  lactic acid 3C 3C NADH NAD + NADH NAD +

Lactic Acid Fermentation ,[object Object],[object Object], Count the carbons ! animals some fungi back to glycolysis  recycle NADH pyruvate  lactic acid 3C 3C NADH NAD + O 2

Pyruvate is a branching point ,[object Object],mitochondria Krebs cycle aerobic respiration fermentation anaerobic respiration O 2 O 2

And how do we do that? ,[object Object],[object Object],[object Object],[object Object],[object Object],ATP But… Have we done that yet? ADP H + H + H + H + H + H + H + H + H + P +

2007-2008 NO ! There’s still more to my s tory ! Any Questions?

Alcohol Fermentation Count the carbons ! ,[object Object],[object Object],[object Object],bacteria yeast back to glycolysis  recycle NADH 1C 3C 2C pyruvate  ethanol + CO 2 NADH NAD +

Chapter 15 lecture 2

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