Transcript Glycolysis
Cellular Respiration Stage 1: Glycolysis AP Biology 2007-2008 What’s the point? The point is to make ATP! ATP AP Biology 2007-2008 Glycolysis Breaking down glucose “glyco – lysis” (splitting sugar) glucose pyruvate 2x 3C 6C ancient pathway which harvests energy where energy transfer first evolved transfer energy from organic molecules to ATP still is starting point for ALL cellular respiration but it’s inefficient generate only 2 ATP for every 1 glucose occurs in cytosol AP Biology That’s not enough ATP for me! In the cytosol? Why does that make evolutionary sense? Evolutionary perspective Prokaryotes first cells had no organelles Enzymes of glycolysis are “well-conserved” Anaerobic atmosphere 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 AP Biology ALL cells still utilize glycolysis You mean we’re related? Do I have to invite them over for the holidays? Overview glucose C-C-C-C-C-C 10 reactions enzyme 2 ATP enzyme 2 ADP convert fructose-1,6bP glucose (6C) to P-C-C-C-C-C-C-P enzyme enzyme 2 pyruvate (3C) enzyme DHAP G3P produces: 4 ATP & 2 NADH P-C-C-C C-C-C-P 2H consumes: 2Pi enzyme 2 ATP enzyme net yield: 2Pi enzyme 2 ATP & 2 NADH DHAP = dihydroxyacetone phosphate AP Biology G3P = glyceraldehyde-3-phosphate pyruvate C-C-C 2 NAD+ 2 4 ADP 4 ATP 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 O2 O2 O2 O2 AP Biology O2 glucose pyruvate 2x 3C 6C Hard way to make a living! But can’t stop there! G3P DHAP NAD+ raw materials products Pi + NADH NAD NADH Pi 1,3-BPG NAD+ Pi + NADH NAD 1,3-BPG NADH 7 ADP Glycolysis 6 Pi ADP ATP ATP 3-Phosphoglycerate (3PG) 3-Phosphoglycerate (3PG) 2-Phosphoglycerate (2PG) 2-Phosphoglycerate (2PG) glucose + 2ADP + 2Pi + 2 NAD+ 2 pyruvate + 2ATP + 2NADH 8 Going to run out of NAD+ 9 H2O without regenerating NAD+, energy production would stop! Phosphoenolpyruvate (PEP) another molecule must accept HADP 10 from NADH ATP so AP Biology NAD+ is freed up for another round Pyruvate H2O Phosphoenolpyruvate (PEP) ADP ATP Pyruvate How is NADH recycled to NAD+? Another molecule must accept H from NADH H2O O2 recycle NADH with oxygen without oxygen aerobic respiration anaerobic respiration “fermentation” pyruvate NAD+ NADH acetyl-CoA CO2 NADH NAD+ lactate acetaldehyde NADH NAD+ lactic acid fermentation which path you use depends on AP Biology who you are… Krebs cycle ethanol alcohol fermentation Fermentation (anaerobic) Bacteria, yeast pyruvate ethanol + CO2 3C NADH 2C NAD+ beer, wine, bread 1C back to glycolysis Animals, some fungi pyruvate lactic acid 3C NADH AP Biology 3C NAD+back to glycolysis cheese, anaerobic exercise (no O2) Alcohol Fermentation pyruvate ethanol + CO2 3C NADH 2C NAD+ back to glycolysis Dead end process at ~12% ethanol, kills yeast can’t reverse the reaction Count the carbons! AP Biology 1C bacteria yeast recycle NADH Lactic Acid Fermentation pyruvate lactic acid 3C NADH 3C NAD+ back to glycolysis Reversible process once O2 is available, lactate is converted back to pyruvate by the liver Count the carbons! AP Biology O2 animals some fungi recycle NADH Pyruvate is a branching point Pyruvate O2 O2 fermentation anaerobic respiration mitochondria Krebs cycle aerobic respiration AP Biology What’s the point? The point is to make ATP! ATP AP Biology 2007-2008 H+ And how do we do that? H + H+ H+ H+ H+ H+ H+ ATP synthase set up a H+ gradient allow H+ to flow through ATP synthase powers bonding of Pi to ADP ADP + P ADP + Pi ATP ATP H+ AP Biology But… Have we done that yet? NO! There’s still more to my story! Any Questions? AP Biology 2007-2008