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Cellular Respiration (Chapter 9)

Learn about cellular respiration and how energy is generated in autotrophs and heterotrophs. Explore aerobic and anaerobic respiration processes, energy transfer mechanisms, and ATP synthesis. Understand the role of NAD, FAD, electron transport chain, and phosphorylation in energy production.

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Cellular Respiration (Chapter 9)

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  1. Cellular Respiration (Chapter 9)

  2. Energy source • Autotrophs: • Producers • Plants, algae and some bacteria • Make own organic molecules • Heterotrophs: • Consumers

  3. Energy • All activities an organism performs requires energy

  4. Cellular respiration C6H12O6 + 6 O2 ---> 6 CO2 + 6 H2O + ATP

  5. Cellular respiration

  6. Cellular Respiration • Catabolic • Enzymes break down substances • Harvest energy from C-H bonds • Or other chemical bonds Organic compounds + oxygen ⇨ Carbon Dioxide + water + energy

  7. Cellular respiration • Aerobic respiration • Chemical energy is harvested • Presence of oxygen • Anaerobic respiration • Process occurs without oxygen • Fermentation

  8. Anaerobic • Glucose to lactate (muscle cells) • Glucose to alcohol (yeast cells) • Does not yield as much energy

  9. Cellular Respiration • Exergonic • -686kcal/mole (-2,870kJ/mole) • Redox reaction • Glucose is oxidized, oxygen is reduced • Energy stored in glucose makes ATP • 38 ATP generated • ATP stores energy for use in cellular functions

  10. Redox reaction becomes oxidized becomes reduced

  11. Vocabulary NAD/NADH FAD ETC Phosphorylation Chemiosmosis ATP Synthase

  12. NAD & NADH • NAD: • Nicotinamide adenine dinucleotide • NAD+ oxidized form • NADH reduced form • NAD+ traps electrons from glucose • Function as energy carrier

  13. NAD & NADH • Dehydrogenase (enzyme) • Removes a pair of hydrogen atoms from glucose • Transfers one proton and 2 electrons to NAD+ H-C-OH + NAD+⇨ -C=O + NADH + H+ • Used to make ATP

  14. 2 e− + 2 H+ 2 e− + H+ NAD+ H+ NADH Dehydrogenase Reduction of NAD+ 2[H] (from food) H+ Oxidation of NADH Nicotinamide (reduced form) Nicotinamide (oxidized form)

  15. FAD • Flavin adenine dinucleotide • Transfers electrons

  16. Electron transport chain • Located inner membrane of mitochondria • Plasma membrane (prokaryotes) • Series of molecules (mostly proteins)

  17. Electron transport chain • Electrons fall to oxygen • In a series of energy releasing steps • High potential energy to low • Energy released generates ATP

  18. Electron transport chain 1/2 O2 + 2 H (from food via NADH) Controlled release of energy for synthesis of ATP 2 H+ + 2 e– ATP ATP Electron transport chain Free energy, G ATP 2 e– 1/2 O2 2 H+ H2O

  19. Phosphorylation • Addition of a phosphate group to a molecule • ATP is formed by a phosphorylation reaction • 1. Substrate-level phosphorylation • 2. Oxidative phosphorylation

  20. Substrate phosphorylation • Enzyme transfers a phosphate from a organic substrate molecule • ADP to make ATP • Direct formation • Glycolysis and Krebs cycle

  21. Oxidation phosphorylation • Energy from electron transport chain • Synthesis ATP • Adds an inorganic phosphate to ADP

  22. Chemiosmosis • Energy-coupling mechanism • Energy stored in hydrogen ion gradient across membrane • Makes ATP from ADP

  23. 2 ATP synthase H+ ADP + ATP P i H+ Chemiosmosis

  24. ATP Synthase • Enzyme helps make ATP • Located in membrane • Changes ADP to ATP • Uses energy from a proton gradient across membrane

  25. INTERMEMBRANE SPACE Stator H+ Rotor Internal rod Catalytic knob ADP + P i ATP MITOCHONDRIAL MATRIX

  26. The Reactions (Cell Respiration) • Glycolysis • Krebs cycle (citric acid cycle) • Electron transport chain (oxidative phosphorylation)

  27. Cellular respiration

  28. Glycolysis • Happens in cytoplasm • Starts with glucose • Yields: • 2 pyruvate (3 carbons) molecules • 4 ATP (net of 2 ATP) & 2 NADH • 10 enzyme catalyzed reactions to complete

  29. Glycolysis • Every living organism can carry out glycolysis • Occur in aerobic & anaerobic • Does not require oxygen • Oxygen present the Krebs cycle will begin

  30. Glycolysis • Part one (priming) • First 5 reactions are endergonic • 2 ATP molecules attach 2 phosphate groups to the glucose • Produces a 6 carbon molecule with 2 high energy phosphates attached

  31. Glycolysis • Part two (cleavage reactions) • 6 carbon molecule is split into 2 • 3-carbon molecules each with a phosphate (G3P)

  32. Glycolysis • Part three (energy harvesting reactions) • In two reactions 2- G3P molecules are changed to pyruvate • 4 ATP molecules are made (net of 2) • An energy rich hydrogen is harvested as NADH (2NADH)

  33. GLYCOLYSIS: Energy Investment Phase Glucose

  34. 1 GLYCOLYSIS: Energy Investment Phase Glucose 6-phosphate ATP Glucose ADP Hexokinase

  35. 1 2 GLYCOLYSIS: Energy Investment Phase Glucose 6-phosphate Fructose 6-phosphate ATP Glucose ADP Phosphogluco- isomerase Hexokinase

  36. 3 GLYCOLYSIS: Energy Investment Phase ATP Fructose 6-phosphate Fructose 1,6-bisphosphate ADP Phospho- fructokinase

  37. 3 4 5 GLYCOLYSIS: Energy Investment Phase Glyceraldehyde 3-phosphate (G3P) ATP Fructose 6-phosphate Fructose 1,6-bisphosphate ADP Isomerase Aldolase Phospho- fructokinase Dihydroxyacetone phosphate (DHAP)

  38. 3 5 2 4 1 GLYCOLYSIS: Energy Investment Phase Glyceraldehyde 3-phosphate (G3P) Fructose 6-phosphate Fructose 1,6-bisphosphate Glucose 6-phosphate ATP ATP Glucose ADP ADP Isomerase Aldolase Hexokinase Phospho- fructokinase Phosphogluco- isomerase Dihydroxyacetone phosphate (DHAP)

  39. 4 5 6 GLYCOLYSIS: Energy Payoff Phase 2 NADH Glyceraldehyde 3-phosphate (G3P) 2 2 NAD+ 2 H+ 2 Triose phosphate dehydrogenase 2 Isomerase 1,3-Bisphospho- glycerate Aldolase Dihydroxyacetone phosphate (DHAP)

  40. 4 6 5 7 GLYCOLYSIS: Energy Payoff Phase ATP 2 2 NADH Glyceraldehyde 3-phosphate (G3P) 2 ADP 2 2 NAD+ 2 H+ 2 2 Triose phosphate dehydrogenase Phospho- glycerokinase 2 Isomerase 1,3-Bisphospho- glycerate 3-Phospho- glycerate Aldolase Dihydroxyacetone phosphate (DHAP)

  41. 8 9 GLYCOLYSIS: Energy Payoff Phase H2O 2 2 2 2 Phospho- glyceromutase Enolase 2-Phospho- glycerate Phosphoenol- pyruvate (PEP) 3-Phospho- glycerate

  42. 8 9 10 Figure 9.9bb-3 GLYCOLYSIS: Energy Payoff Phase ATP 2 H2O 2 ADP 2 2 2 2 2 Phospho- glyceromutase Enolase Pyruvate kinase 2-Phospho- glycerate Phosphoenol- pyruvate (PEP) Pyruvate 3-Phospho- glycerate

  43. 6 9 8 7 10 GLYCOLYSIS: Energy Payoff Phase ATP 2 ATP 2 2 H2O 2 NADH 2 ADP ADP 2 2 H+ 2 NAD+ 2 2 2 2 + 2 Phospho- glycerokinase Phospho- glyceromutase Enolase Triose phosphate dehydrogenase Pyruvate kinase 2 Glycer- aldehyde 3-phosphate (G3P) 1,3-Bisphospho- glycerate 3-Phospho- glycerate 2-Phospho- glycerate Phosphoenol- pyruvate (PEP) Pyruvate

  44. Electron shuttles span membrane 2 NADH or 2 FADH2 2 NADH GLYCOLYSIS Glucose 2 Pyruvate + 2 ATP

  45. Glycolysis • Glucose converted to pyruvate. • First half uses 2 ATP • Forms 2 separate G3P (glyceraldehyde 3-phosphate)

  46. Glycolysis • Second half generates 4 ATP, 2 NADH & 2 pyruvate • Net results are 2 ATP, 2 NADH and 2 pyruvate • Takes place in the cytoplasm

  47. Oxidation of pyruvate • Pyruvate is changed into acetyl-CoA • First carboxyl group is removed • Leaves as carbon dioxide • 2 carbon molecule called acetate remains

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