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CELLULAR RESPIRATION II

CELLULAR RESPIRATION II. How Cells Obtain Energy to Sustain Life. CELLULAR RESPIRATION. Three Major Phases: Glycolysis Krebs Cycle 3. Electron Transport Chain. CELLULAR RESPIRATION BEGINS IN THE CYTOPLASM. Glucose Metabolism (first part of respiration):

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CELLULAR RESPIRATION II

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  1. CELLULAR RESPIRATION II How Cells Obtain Energy to Sustain Life

  2. CELLULAR RESPIRATION Three Major Phases: • Glycolysis • Krebs Cycle 3. Electron Transport Chain

  3. CELLULAR RESPIRATION BEGINS IN THE CYTOPLASM Glucose Metabolism (first part of respiration): • Starts in cytoplasm of cells of all organisms • Aerobic & Anaerobic • Glycolosis • Lysis = break down • Glyco = prefix for sugar

  4. THE GLYCOLYTIC PATHWAY Energy Input: ATP

  5. THE GLYCOLYTIC PATHWAY End product:2 pyruvate molecules (Energy Output) ATP Reduced Helper NADH

  6. SUMMARY OF GLYCOLYSIS • Glycolysis: • One Glucose molecule (6 C) is transformed into two (3 C) organic molecules called “pyruvate”

  7. SUMMARY OF GLYCOLYSIS Additionally, the Enzyme Mediated Reactions of Glycolysis Yield: • ATP molecules • Reduced Helper (NADH) (NAD+ + H & 2e-  NADH) ***NOTE: NADH is a high energy e- carrier that will become important later!***

  8. TWO PATHWAYS FOLLOWING GYLCOLYSIS • In Absence of Oxygen: • Anaerobic Respiration • In Presence of Oxygen: • Aerobic Respiration

  9. FERMENTATION • In Absence of Oxygen: • Energy production occurs • through Fermentation • Occurs in cytoplasm • Only yields 2 ATP per glucose but occurs fast

  10. TWO PATHWAYS AFTER GLYCOLYSIS In Presence of Oxygen: • Aerobic Respiration

  11. AEROBIC RESPIRATION OCCURS IN MITOCHONDRIA Transition Reactions: • Mitochondrial membrane Krebs Cycle: • Mitochondrial matrix Electron Transport Chain: • Inner membrane of mitochondria

  12. THE TRANSITION REACTIONS Transition Reaction: • Pyruvate converted into Acetyl-CoA • Reduced helper (NADH) produced • CO2 produced

  13. KREBS CYCLE • We Continue a Series of Redox Reactions During Krebs Cycle

  14. SUMMARY OF KREB’S CYCLE • Kreb’s Cycle: • 2 acetyl Co A produce: • Reduced helpers • ATP • CO2

  15. OVERVIEW SO FAR… During Glycolysis, Transition Reactions & Krebs: • Organic molecules are oxidized • Eventually all C in glucose is found in CO2 • Helper Molecules Reduced • NAD+ NADH • FAD  FADH2 • Very little ATP produced

  16. SUMMARY OF AEROBIC RESPIRATION

  17. SUMMARY OF AEROBIC RESPIRATION SO FAR…..

  18. ELECTRON TRANSPORT CHAIN • In the last phase of cellular respiration, electrons are donated to proteins in the mitochondrial inner membrane

  19. ELECTRON TRANSPORT CHAIN • ETC occurs at mitochondrial inner membrane • Helper molecules donate e-s to proteins embedded in membrane e-

  20. ELECTRON TRANSPORT CHAIN • ETC: • Series of Redox Reactions where: • Proteins pass e-s down chain • Ea. protein is more electronegative • than preceding • Oxygen is final e- acceptor • Water forms when Oxygen combines • with electrons & 2 H+ e-

  21. ELECTRON TRANSPORT CHAIN Some Proteins: • Carry electrons (only) • Carry electrons while pumping protons: H+ • H+ pumped from matrix  inter- membrane space • Creates electrochem. gradient

  22. ELECTRON TRANSPORT CHAIN Electrochemical Gradient: • Source of power for ATP synthesis! High H+ Low H+

  23. ELECTRON TRANSPORT CHAIN ATP SYNTHESIS: • ATP synthesis is coupled to diffusion of H+ through ATP Synthase

  24. ELECTRON TRANSPORT CHAIN ATP Synthesis: • H+ returns to matrix (moving down its gradient) • ATP synthase attaches inorganic phosphate to ADP • “Oxidative Phosphorylation” • ATP produced!

  25. ELECTRON TRANSPORT CHAIN

  26. CELLULAR RESPIRATION • Most ATP is Synthesized During the ETC

  27. CONCLUSIONS: CELLULAR RESPIRATION Cellular (aerobic) Respiration: • Involves series of redox reactions that release energy for ATP synthesis • Begins with breakdown of sugar and ends with ATP synthesis through ATP Synthase • By products include: • H2O & CO2

  28. METABOLISM OF MACROMOLECULES IS TIED TO CELLULAR RESPIRATION • In absence of carbs, other molecules can be used to produce chemical energy: • Proteins • Fats

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