2 Glycolysis is only the start Pyruvate has more energy to yield3 more C to strip off (to oxidize)if O2 is available, pyruvate enters mitochondriaenzymes of Krebs cycle complete the full oxidation of sugar to CO22x6C3Cglucose pyruvateCan’t stop at pyruvate == not enough energy producedPyruvate still has a lot of energy in it that has not been captured.It still has 3 carbons! There is still energy stored in those bonds.pyruvate CO23C1C
4 Mitochondria — Structure Double membrane energy harvesting organellesmooth outer membranehighly folded inner membrane____________________________________________fluid-filled space between membranesinner fluid-filled spacemitochondrial DNA, ribosomesenzymesfree in matrix & membrane-boundintermembranespaceinnermembraneoutermatrixcristaemitochondrial DNAWhat cells would have a lot of mitochondria?
5 Mitochondria – Function Oooooh! Form fits function!Mitochondria – FunctionDividing mitochondriaWho else divides like that?Membrane-bound proteinsEnzymes & permeasesAlmost all eukaryotic cells have mitochondriathere may be 1 very large mitochondrion or 100s to 1000s of individual mitochondrianumber of mitochondria is correlated with aerobic metabolic activitymore activity = more energy needed = more mitochondriaWhat cells would have a lot of mitochondria?Active cells:• muscle cells• nerve cellsWhat does this tell us about the evolution of eukaryotes?__________________________Advantage of highly folded inner membrane?____________________________ ____________________________
6 pyruvate acetyl CoA + CO2 Oxidation of pyruvatePyruvate enters mitochondrial matrix3 step oxidation processreleases _______ (count the carbons!)reduces _______________ (moves e-)produces __________________Acetyl CoA enters ________________[2x]pyruvate acetyl CoA + CO23CNAD2C1CWhere does the CO2 go?Exhale!CO2 is fully oxidized carbon == can’t get any more energy out itCH4 is a fully reduced carbon == good fuel!!!
7 Pyruvate oxidized to Acetyl CoA NAD+reductionCoenzyme AAcetyl CoAPyruvateRelease CO2 because completely oxidized…already released all energy it can release … no longer valuable to cell….Because what’s the point?The Point is to make ATP!!!CO2C-CC-C-Coxidation2 x Yield = 2C sugar + NADH + CO2
8 Krebs cycle 1937 | 1953 aka Citric Acid Cycle in _________________________8 step pathwayeach catalyzed by specific enzymestep-wise catabolism of 6C citrate moleculeEvolved later than glycolysisdoes that make evolutionary sense?bacteria 3.5 billion years ago (glycolysis)free O2 2.7 billion years ago (photosynthesis)eukaryotes 1.5 billion years ago (aerobic respiration = organelles mitochondria)Hans Krebs
9 Count the carbons! x2 3C 2C 4C 6C 4C 6C 5C 4C 4C 4C pyruvate3C2Cacetyl CoAcitrate4C6C4C6CThis happens twice for each glucose moleculeoxidation of sugarsCO2A 2 carbon sugar went into the Krebs cycle and was taken apart completely. Two CO2 molecules were produced from that 2 carbon sugar. Glucose has now been fully oxidized!But where’s all the ATP???x25C4CCO24C4C
10 __________ __________ __________ Count the electron carriers!CO2pyruvate3C2Cacetyl CoANADHNADHcitrate4C6C4C6C__________ __________ __________This happens twice for each glucose moleculeCO2Everytime the carbons are oxidized, an NAD+ is being reduced.But wait…where’s all the ATP??NADHx25C4CFADH2CO24C4CNADHATP
11 Whassup? So we fully oxidized glucose C6H12O6 CO2 & ended up with 4 ATP!What’s the point?
12 What’s so important about electron carriers? Electron Carriers = Hydrogen CarriersH+Krebs cycle produces large quantities of ___________________________go to Electron Transport Chain!ADP + PiATPWhat’s so important about electron carriers?
13 Energy accounting of Krebs cycle 2x4 NAD + 1 FAD4 NADH + 1 FADH2pyruvate CO21 ADP1 ATP3C3x1CATPNet gain = 2 ATP= 8 NADH + 2 FADH2
14 Value of Krebs cycle?If the yield is only 2 ATP then how was the Krebs cycle an adaptation?______________________________________________________________________like $$ in the bank