Modified from Kim Foglia Today I will… 1.Describe the process of glycolysis. 2.State the reactants and products of glycolysis.

ATP What’s the point?

glucose      pyruvate 2x2x 6C3C  Breaking down glucose ◦ “glyco – lysis” (splitting sugar) ◦ most ancient form of energy capture  starting point for all cellular respiration ◦ inefficient  generate only 2 ATP for every 1 glucose ◦ occurs in cytosol  why does that make evolutionary sense?

 Life on Earth first evolved without free oxygen (O 2 ) in atmosphere ◦ energy had to be captured from organic molecules in absence of O 2  Prokaryotes that evolved glycolysis are ancestors of all modern life ◦ ALL organisms still utilize glycolysis

10 reactions ◦ convert 6C glucose to two 3C pyruvate ◦ produce 2 ATP & 2 NADH glucose C-C-C-C-C-C fructose-6P P-C-C-C-C-C-C-P DHAP P-C-C-C G3P (PGAL) C-C-C-P pyruvate C-C-C 2 ATP 2 ADP 2 NAD + 2 NADH 4 ADP 4 ATP activation energy G3P = glyceraldehyde-3-phosphate DHAP = dihydroxyacetone phosphate 2 P i

endergonic invest some ATP exergonic harvest a little ATP & a little NADH yield 2 ATP 2 NADH

 Glucose “priming” ◦ get glucose ready to split  phosphorylate glucose  rearrangement ◦ split destabilized glucose PGAL

 Energy Harvest ◦ NADH production  G3P donates H  oxidize sugar  reduce NAD +  NAD +  NADH ◦ ATP production  G3P  pyruvate  sugars donate P  ADP  ATP

ATP  Net gain = 2 ATP ◦ some energy investment (-2 ATP) ◦ small energy return (+4 ATP)  1 6C sugar  2 3C sugars 2 ATP2 ADP 4 ADP4 ATP glucose      pyruvate 2x2x 6C3C

 Not a lot of energy… ◦ for 1 billon years + this is how life on Earth survived… Why?  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

glucose + 2ADP + 2P i + 2 NAD +  2 pyruvate + 2ATP + 2NADH glucose + 2ADP + 2P i + 2 NAD +  2 pyruvate + 2ATP + 2NADH Glycolysis  Going to run out of NAD + ◦ without regenerating NAD+, energy production would stop ◦ another molecule must accept H from NADH NADH How is NADH recycled to NAD + ?

 Another molecule must accept H from NADH ◦ aerobic respiration  to Electron Transport Chain in mitochondria ◦ anaerobic respiration  ethanol fermentation  lactic acid fermentation O2O2 O2O2 NADH which path you use depends on who you are…

 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 + to glycolysis

1C 3C2C pyruvate  ethanol + CO 2 NADHNAD +  Dead end process  at ~12% ethanol, kills yeast  can’t reverse the reaction bacteria yeast

 Reversible process  once O 2 is available, lactate is converted to pyruvate by liver pyruvate  lactic acid 3C NADHNAD +  O2O2 animals

Pyruvate O2O2 O2O2 Kreb’s cycle mitochondria fermentation

ATP What’s the point?

H+H+ ADP + P i H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+  Set up a H + gradient  Allow the H + to flow through ATP synthase ADP + P i  ATP ATP Have we done that yet?