Cellular Respiration Obtain energy from the degradation of sugars Uses Oxygen and produces CO 2 Many steps take place in the mitochondria of cells Complementary process to photosynthesis  Will recognize many of the same molecules

Oxidation-Reduction reactions Type of reaction when an electron is transferred from one atom or molecule to another  Electron donor is reducing agent  Electron acceptor is oxidizing agent  The addition of electron to a molecule or atom is called reduction Energy is released when electrons are transferred to lower energy state molecules  Electron transfer chains

Cellular Respiration Mechanisms 3 Stages  Glycolysis-happens in cytosol of cell  Krebs cycle-happens in matrix of mitochondria  Electron transport and oxidative phophorylation-cristae

Glycolysis Means “sugar splitting”-glucose is split into Pyruvate First step of respiration Broken into two stages  Energy investment phase-uses 2ATP  Energy Payoff Phase-Yields 4 ATP +2 NADH  Net of 2 ATP

Energy Investment Phase Begins with Glucose 2 ATPs are used to phosphorylate Carbons 1 and 6  Activated intermediates Isomerase converts glucose to fructose structure  Isomerase is enzyme that changes one molecule to an isomer Eventually yields 2 molecules of glyceraldehyde phosphate  Enters energy payoff phase

Fig. 9-8 Energy investment phase Glucose 2 ADP + 2 P 2 ATPused formed 4 ATP Energy payoff phase 4 ADP + 4 P 2 NAD e – + 4 H + 2 NADH + 2 H + 2 Pyruvate + 2 H 2 O Glucose Net 4 ATP formed – 2 ATP used2 ATP 2 NAD e – + 4 H + 2 NADH + 2 H +

Energy Payoff Phase Starts with Glyceraldehyde phosphate  2 for every glucose Enzyme adds phosphate GP while 2 NADH molecules are produces Phosphates are eventually loss resulting in the production of 4 ATP molecules The final product is Pyruvate  Moves into Krebs cycle

Transition Once Pyruvate enters Mitochondrion it is converted to Acetyl CoA and CO 2  Acetyl CoA is the starting molecule for the Krebs cycle

Fig CYTOSOLMITOCHONDRION NAD + NADH+ H Pyruvate Transport protein CO 2 Coenzyme A Acetyl CoA

Krebs cycle Completes the oxidation of organic molecules Takes place in matrix of mitochondria Cyclic like Calvin cycle Produces 1 ATP for each acetyl CoA  2 per glucose Many high energy electrons are saved as 3NADH and FADH 2 per cycle Also produces 2 CO 2 molecules per cycle

Fig Acetyl CoA CoA—SH Citrate H2OH2O Isocitrate NAD + NADH + H + CO2CO2  -Keto- glutarate CoA—SH CO2CO2 NAD + NADH + H + Succinyl CoA CoA—SH P i GTP GDP ADP ATP Succinate FAD FADH 2 Fumarate Citric acid cycle H2OH2O Malate Oxaloacetate NADH +H + NAD

Fig Pyruvate NAD + NADH + H + Acetyl CoA CO 2 CoA Citric acid cycle FADH 2 FAD CO NAD H + ADP +P i ATP NADH

Transition 2 NADH and FADH2 are used in the electron transport chain  Happens in cristae of mitochondrion  Uses Oxygen as ultimate electron acceptor