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2006-2007 Today I will… 1. Describe the process of glycolysis. 2. State the reactants and products of glycolysis. Modified from Kim Foglia What’s the point? ATP 2006-2007 Breaking down glucose ◦ “glyco – lysis” (splitting sugar) glucose pyruvate 2x 3C 6C ◦ 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 (O2) in atmosphere ◦ energy had to be captured from organic molecules in absence of O2 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 2 ATP 2 ADP fructose-6P P-C-C-C-C-C-C-P DHAP P-C-C-C 2 Pi G3P = glyceraldehyde-3-phosphate DHAP = dihydroxyacetone phosphate G3P (PGAL) C-C-C-P 2 NAD+ pyruvate C-C-C 2 NADH 4 ADP 4 ATP 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 2 ATP 2 ADP glucose pyruvate 6C 4 ADP 2x 3C 4 ATP Net gain = 2 ATP 1 6C sugar 2 3C sugars ◦ some energy investment (-2 ATP) ◦ small energy return (+4 ATP) 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 O2 O2 O2 O2 O2 glucose pyruvate 2x 3C 6C glucose + 2ADP + 2Pi + 2 NAD+ Glycolysis 2 pyruvate + 2ATP + 2NADH glucose + 2ADP + 2Pi + 2 NAD+ 2 pyruvate + 2ATP + 2NADH Going to run out of NAD+ ◦ without regenerating NAD+, energy production would stop ◦ another molecule must accept H from NADH How is NADH recycled to NAD+? NADH Another molecule must accept H from NADH ◦ aerobic respiration O2 to Electron Transport Chain in mitochondria ◦ anaerobic respiration ethanol fermentation lactic acid fermentation NADH which path you use depends on who you are… O2 Bacteria, yeast pyruvate ethanol + CO2 3C NADH beer, wine, bread 2C NAD+ to glycolysis Animals, some fungi pyruvate lactic acid 3C NADH 3C NAD+to glycolysis cheese, anaerobic exercise (no O 2) 1C bacteria yeast pyruvate ethanol + CO2 3C NADH 2C NAD+ Dead end process at ~12% ethanol, kills yeast can’t reverse the reaction 1C animals pyruvate lactic acid NADH 3C NAD+ 3C Reversible process once O2 is available, lactate is converted to pyruvate by liver O2 Pyruvate O2 O2 fermentation Kreb’s cycle mitochondria What’s the point? ATP 2006-2007 H+ H+ H+ H+ H+ H+ H+ H+ Set up a H+ gradient Allow the H+ to flow through ATP synthase ADP + Pi ATP ADP + Pi ATP Have we done that yet? H+