Cellular Respiration Introduction step Living organisms go through a series of steps to metabolize glucose using enzymes along every More steps more possibilities to capture all the energy made from glucose Metabolism of Glucose C6H12O6 6O2 6CO2 6H20 Free energy G is negative Exergonic reaction will feed energy into an endergonic reaction o Metabolism of glucose ATP synthesis Three Metabolic processes for use of glucose are o Glycolysis o Cellular Respiration o Fermentation Cellular Locations for Energy Pathways in Eukaryotes and Prokaryotes Mitochondria Outer and inner membranes The intermembrane space space between outer and inner membranes The cristae infoldings of the inner membrane The matrix space within the inner membrane Origin Endosymbiosis theory o Presence of mitochondria is present because it once was a prokaryotic cell that was en gulfed by a eukaryotic cell o Why they have two membranes Small size 5 10 m like chloroplast Circular DNA Stages of Aerobic Representation 1 Glycolysis happens outside the mitochondria in the cytoplasm a Does not require the presence of oxygen b Glucose will be transformed into pyruvate i Initial formation of ATP 2ATP c Glucose must first enter the cell through diffusion i Facilitated Diffusion 2 Pyruvate Acetyl CoA 3 Citric Acid Cycle a 2 ATP b Electron Transport and chemiosmosis Electrons continually get moved around then through electron transport in the last part of aer obic respiration there is a large production of ATP 32 ATP Little steps in order to get as much ATP as possible or else energy would become heat Glycolysis Glucose will enter the cell through facilitated diffusion a k a passive transport Cytosol No O2 required o First breakdown of glucose ATP is required to start the process Glucose Fructose 1 6 bisphosphate o 3 steps o phosphate added to 1st and 6th glucose Fructose 1 6 bisphosphate 2 Glyceraldehyde phosphate G3P Energy capture phase Four ATPs and two NADH produced per glucose 2 G3P Pyruvate o 5 steps o NAD NADH o 2 ADP 2 ATP Substrate level phosphorylation Two phases o Endergonic Require ATP o Exergonic yield ATP and NADH substrate level phosphorylation From glucose to 2 pyruvate Net yield o 2 ATP molecules o 2 NADH molecules Pyruvate moves to matrix Pyruvate is oxidized oxidative decarboxylation to acetate and converted to Acetyl CoA Pyruvate Conversion to Acetyl CoA CO2 will diffuse out to the cell Enzymes o Pyruvate Dehydrogenase enzyme complex very large o Coenzyme A from vitamin B and panthothenic acid Is going to transfer an acetyl group Overall Reaction o 2 pyruvate 2NAD 2 CoA 2 acetyl CoA 2NADH 2 CO2 Citric Acid Cycle Starting point Acetyl CoA Takes place in the matrix Concentrations are fairly the same in order to keep the cycle going Production of Multiply by 2 because for every glucose there are 2 acetyl CoA o FADH2 another electron carrier that will be reduced o 3 NADH o 2 CO2 o ATP How does the oxidation of glucose to ATP Electron transport chain Chemiosmosis Electron Transport Chain Inner mitochondrial membrane contains all proteins that form parts of the electron transport chain Big proteins form four different complexes Functions of proteins is to receive electrons and transfer electrons Four Complexes o Receive Complex I NADH Ubiquinone reductase accepts e from NADH o Receive Complex II Succinate ubiquinone reductase accepts e from FADH2 o Can t just keep accepting electrons arrows to transfer electrons o Transfer Complex II Ubiquinone cytochrome C OR passes e to cytochrome C o Transfer Complex IV Cytochrome C oxidase O2 terminal e acceptor must be the terminal water 2H 1 2O2 H2O Complex I III and IV H can move across to the intermembrane space Complex V ATP synthase o ATP Synthesis by oxidative phosphorylation Energy is going to come from the electrons ADP ATP Complexes use the energy from the electrons to move the protons across the inner mitochondrial membrane o Causes a higher concentration of protons H in the intermembrane space Creates a higher gradient The only way the H can go back into the matrix of the mitochondrion is through Complex V ATP Synthase Chemiosmosis Model explains the coupling of ATP synthesis to e transport Protons are stuck in the Intermembrane space They only way they can cross is through the Complex V ATP Synthase They cannot go from high to low concentration gradient As e pass down the ETC energy is used to move H proton pumping into intermembrane space Such a high concentration of H causes a very low pH H pH ATP Synthesis by oxidative phosphorylation Different from transfer of phosphate groups o o o o Energy Yield From Oxidation of Glucose by Aerobic Respiration According to the cell type on certain occasions we must use energy to move NADH from cytoplasm to the interior of the mitochondria i e liver cells and muscle cells Total of 36 ATP from glucose o ATP is mostly produced by oxidative phosphorylation Control of Cellular Respiration o o o Lack of O2 blacks the entire ETC Without oxygen you will only get a very tiny amount of ATP You can still do anaerobic respiration Enzyme Inhibition Many chemicals can inhibit the activity of cytochromes Some poisons inhibit activity of cytochromes Will bind in an irreversible way i e if one protein is damaged on the ETC it will not be able to follow through Example cyanide binds to iron to cytochrome blocking ATP produc tion Aerobic Respiration Anaerobic Respiration and Fermentation