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Mastering Cellular Respiration Fundamentals

Explore the intricate process of cellular respiration in organisms, understanding how energy is harvested through catabolism and converted into ATP. Learn about glycolysis, Krebs cycle, electron transport chain, and more in this comprehensive guide.

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Mastering Cellular Respiration Fundamentals

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  1. Cellular Respiration (Chapter 9)

  2. Energy • Plants, algae & some bacteria • Convert radiant energy (sun) into chemical energy (glucose)

  3. Harvest Energy • All activities an organism performs requires energy

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

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

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

  7. Cellular respiration

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

  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. Vocabulary (Cell respire) NAD/NADH FAD ETC Phosphorylation Chemiosmosis ATP Synthase

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

  12. 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

  13. NAD & NADH

  14. FAD • Flavin adenine dinucleotide • Transfers electrons

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

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

  17. 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

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

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

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

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

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

  23. The Reactions---Cell respire • Glycolysis • Krebs cycle (citric acid cycle) • Electron transport chain (oxidative phosphorylation)

  24. Cellular respiration

  25. 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

  26. 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

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

  28. 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)

  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. Glucose ATP 1 Hexokinase ADP Fig. 9-9-1 Glucose Glucose-6-phosphate ATP 1 Hexokinase ADP Glucose-6-phosphate

  31. Glucose ATP 1 Hexokinase ADP Fig. 9-9-2 Glucose-6-phosphate Glucose-6-phosphate 2 Phosphoglucoisomerase 2 Phosphogluco- isomerase Fructose-6-phosphate Fructose-6-phosphate

  32. Glucose ATP 1 1 Hexokinase ADP Fig. 9-9-3 Fructose-6-phosphate Glucose-6-phosphate 2 2 Phosphoglucoisomerase ATP 3 Phosphofructo- kinase Fructose-6-phosphate ATP ADP 3 3 Phosphofructokinase ADP Fructose- 1, 6-bisphosphate Fructose- 1, 6-bisphosphate

  33. Glucose ATP 1 Hexokinase ADP Fig. 9-9-4 Glucose-6-phosphate 2 Phosphoglucoisomerase Fructose- 1, 6-bisphosphate 4 Fructose-6-phosphate Aldolase ATP 3 Phosphofructokinase ADP 5 Isomerase Fructose- 1, 6-bisphosphate 4 Aldolase 5 Isomerase Glyceraldehyde- 3-phosphate Dihydroxyacetone phosphate Glyceraldehyde- 3-phosphate Dihydroxyacetone phosphate

  34. 2 NAD+ 6 Triose phosphate dehydrogenase 2 P 2 NADH i + 2 H+ 2 2 1, 3-Bisphosphoglycerate Glyceraldehyde- 3-phosphate Fig. 9-9-5 2 NAD+ 6 Triose phosphate dehydrogenase P 2 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate

  35. 2 NAD+ 6 Triose phosphate dehydrogenase 2 P 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate 2 ADP 7 Phosphoglycerokinase Fig. 9-9-6 2 ATP 2 1, 3-Bisphosphoglycerate 2 ADP 2 3-Phosphoglycerate 7 Phosphoglycero- kinase 2 ATP 2 3-Phosphoglycerate

  36. 2 NAD+ 6 Triose phosphate dehydrogenase 2 P 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate 2 ADP 7 Phosphoglycerokinase Fig. 9-9-7 2 ATP 2 3-Phosphoglycerate 2 3-Phosphoglycerate 8 Phosphoglyceromutase 8 Phosphoglycero- mutase 2 2-Phosphoglycerate 2 2-Phosphoglycerate

  37. 2 NAD+ 6 Triose phosphate dehydrogenase 2 P 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate 2 ADP 7 Phosphoglycerokinase Fig. 9-9-8 2 ATP 2 2-Phosphoglycerate 2 3-Phosphoglycerate 8 Phosphoglyceromutase 9 Enolase 2 H2O 2 2-Phosphoglycerate 9 Enolase 2 H2O 2 Phosphoenolpyruvate 2 Phosphoenolpyruvate

  38. 2 NAD+ 6 Triose phosphate dehydrogenase P 2 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate 2 ADP 7 Phosphoglycerokinase Fig. 9-9-9 2 ATP Phosphoenolpyruvate 2 2 ADP 2 3-Phosphoglycerate 8 10 Phosphoglyceromutase Pyruvate kinase 2 ATP 2 2-Phosphoglycerate 9 Enolase 2 H2O 2 Phosphoenolpyruvate 2 ADP 10 Pyruvate kinase 2 ATP Pyruvate 2 2 Pyruvate

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

  40. Oxidation of pyruvate • Pyruvate dehydrogenase • Multienzyme complex • Combines acetate (acetyl group) with a coenzyme called coenzyme A. • Product is acetyl-CoA • Plus one NADH

  41. Oxidation of pyruvate • Pyruvate dehydrogenase • Largest known enzyme • 60 subunits • Process occurs within mitochondria • Acetyl-CoA is end product of the break down of fats and proteins too

  42. CYTOSOL MITOCHONDRION Fig. 9-10 NAD+ NADH + H+ 2 1 3 Acetyl CoA Coenzyme A Pyruvate CO2 Transport protein

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