Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

  • Published on

  • View

  • Download

Embed Size (px)


Chapter 9

Chapter 4 Cells and EnergyCellular RespirationCellular respirationProcess by which food molecules are broken down to release energyGlucose and other 6-carbon sugars are major sources of energyAerobic processes require oxygenAnaerobic processes dont need oxygenReleasing energy with O2process involves 4 stepsGlycolysisConverting pyruvic acid to acetic acidCitric acid cycle (Krebs cycle)Electron transport chainGlycolysis6-carbon glucose breaks down to 2 molecules of pyruvic acid (each with 3-carbons)No oxygen requiredAlso produces 2H+ ions and 2electrons that are picked up by 2NAD+ Uses 2ATP and produces 4ATP (net production of 2ATP)Occurs in cytoplasmSection 9.3 Summary pages 231-237Glycolysis

Glucose2ATP2ADP2PGAL4ADP + 4P2NAD+2NADH + 2H+4ATP2 Pyruvic acid

FermentationLactic AcidPyruvic acid from glycolysis is converted to lactic acidNADH + H+ is recycled to NAD+ Alcoholic Pyruvic acid from glycolysis is converted to ethyl alcohol and carbon dioxideNADH + H+ is recycled to NAD+FermentationLactic acid fermentation occurs in cytoplasm of muscle cells (causes muscle soreness)Alcoholic fermentation occurs in bacteria and yeastBoth forms occur in the cytoplasm WITHOUT oxygenPyruvic acid to acetic acid2 Pyruvic acids moves from the cytoplasm into the mitochondriaEach pyruvic acid loses a C to CO2 to make acetic acid2 Acetic acids are combined with coenzyme A to make 2 acetyl-CoA2H+ and 2 electrons are picked up by NAD+

Section 9.3 Summary pages 231-237

Pyruvic acidOutside the mitochondrionMitochondrial membraneInside the mitochondrionPyruvic acidIntermediate by-productNAD+NADH + H+CO2Coenzyme A- CoAAcetyl-CoAPyruvic Acid

Citric acid cycle (Krebs cycle)Each acetyl-CoA enters the cycle and combines with the 4-carbon oxaloacetic acid to make citric acidCitric acid loses a C to CO2 and releases H+ to NAD+ to become ketoglutaric acidKetoglutaric acid loses a C to CO2, stores energy in an ATP and releases H+ and electrons to NAD+ to make succinic acidKrebs continuedSuccinic acid releases H+ and electrons to NAD+ and FAD and converted back to oxaloacetic acidProducts of Krebs cycle4 CO22 ATP6 NADH + H+2 FADH

Section 9.3 Summary pages 231-237The Citric Acid Cycle

(Acetyl-CoA)Citric acidNAD+NADH + H+


O==O(CO2)ADP +

ATPFADFADH2Citric Acid CycleNAD+NADH + H+Oxaloacetic acidThe mitochondria host the citric acid cycle.NADH + H+

Electron Transport ChainAll NADH + H+ and FADH produced go to the electron transport chainEach NADH + H+ produces 3 ATP (30 ATP)Each FADH produces 2 ATP (4 ATP)Electron transport chain produces a total of 34 ATP

Section 9.3 Summary pages 231-237The electron transport chain

EnzymeElectron carrier proteinse -NADHFADH2NAD+FADElectron pathway4H+ + O2+ 4 electronsH2OH2OADP +ATPInner membraneCenter of mitochondrionSpace between inner and outer membranes

Total ATP productionNet ATP in glycolysis is 2ATP production in Krebs is 2ATP production in ETC is 34

Total = 38 ATP


View more >