Cell respiration

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Cell respiration

  1. 1. Cellular Respiration
  2. 2. Figure 8.UN01Figure 8.UN01 Metabolic Pathways Often Require Multiple Steps Enzyme 1 Enzyme 2 Enzyme 3 Reaction 1 Reaction 2 Reaction 3 ProductStarting molecule A B C D
  3. 3. Figure 8.UN01Figure 8.UN01 Metabolic Pathways Often Require Multiple Steps Enzyme 1 Enzyme 2 Enzyme 3 Reaction 1 Reaction 2 Reaction 3 ProductStarting molecule A B C D What happens when one of these steps goes awry?
  4. 4. Case Study: Why is Patrick Paralyzed? Maureen Knabb Department of Biology West Chester University
  5. 5. Patrick at Ages 2 and 21Patrick at Ages 2 and 21 Patrick at 2: • When Patrick was 16 years old, his hand started twitching as he picked up a glass at dinner. • Five months later (in February 2001), he fell down the steps at his home and was unable to climb the steps to the bus. He went to the ER for his progressive weakness. • At Children’s Hospital of Philadelphia he was initially diagnosed with a demyelinating disease. • He was treated with anti-inflammatory drugs and antibodies for 2 years with no improvement. • What was wrong with Patrick? By the time Patrick was 21 he was completely paralyzed Why did Patrick lose his ability to move?
  6. 6. What could be responsible for Patrick’sWhat could be responsible for Patrick’s loss of mobility?loss of mobility? A: His nervous system is not functioning properly. B: His muscles are not functioning properly. C: He cannot efficiently break down food for energy. D: All of the above are possible causes.
  7. 7. Which of the following processes requiresWhich of the following processes requires energy?energy? A: Creating ion gradients across membranes. B: Muscle shortening. C: Protein synthesis. D: All of the above.
  8. 8. Figure 8.8aFigure 8.8a (a) The structure of ATP Adenosine Triphosphate (ATP) is the Primary Energy Carrier in the Cell
  9. 9. 3 Phosphate groups (triphosphate) Adenine Ribose (a) The structure of ATP Figure 8.8a Adenosine Triphosphate (ATP) is the Primary Energy Carrier in the Cell
  10. 10. What would happen if Patrick lost his abilityWhat would happen if Patrick lost his ability to make ATP?to make ATP? A: His muscles would not be able to contract. B: His neurons would not be able to conduct electrical signals. C: Both A and B. 11
  11. 11. How is ATP generated?How is ATP generated? • ATP is formed through metabolic pathways. • In metabolic pathways, the product of one reaction is a reactant for the next. • Each reaction is catalyzed by an enzyme. 12 Enzyme 1 Enzyme 2 Enzyme 3 Reaction 1 Reaction 2 Reaction 3 ProductStarting molecule A B C D
  12. 12. What are enzymes?What are enzymes? • Enzymes (usually proteins) are biological catalysts that are highly specific for their substrates (i.e., reactants). • Enzymes are not consumed in the reaction. • Enzymes lower the activation energy (the initial energy to start a reaction) of a reaction o Speed up chemical reactions
  13. 13. Course of reaction without enzyme EA without enzyme EA with enzyme is lower Course of reaction with enzyme Reactants Products ∆G is unaffected by enzyme Progress of the reaction Freeenergy
  14. 14. Enzyme RegulationEnzyme Regulation • Enzymes turn “on” and “off” based on the needs of the cell o Activators: Turn enzymes “ON” • Positive allosteric regulation o Inhibitors turn enzymes off • Irreversible = must make new enzyme! • Reversible = inhibitor can “come off” o Competitive inhibition = active site o Noncompetitive inhibition = “other” site = allosteric site • Feedback Inhibition
  15. 15. CQ6: In competitive inhibition…CQ6: In competitive inhibition… A: the inhibitor competes with the normal substrate for binding to the enzyme's active site. B: an inhibitor permanently inactivates the enzyme by combining with one of its functional groups. C: the inhibitor binds with the enzyme at a site other than the active site. D: the competing molecule's shape does not resemble the shape of the substrate molecule.
  16. 16. Consider the metabolic pathway below. If the enzyme responsible forConsider the metabolic pathway below. If the enzyme responsible for converting A to C was mutated and nonfunctional, what would happen?converting A to C was mutated and nonfunctional, what would happen? A: Levels of A would increase; levels of B, C, and D would decrease. B: Levels of A and B would increase; levels of C and D would decrease. C: Levels of A, B and C would increase; levels of D would decrease. D: Levels of A, B, C, and D would all decrease. A C D B
  17. 17. DNA mutations can disruptDNA mutations can disrupt metabolic pathwaysmetabolic pathways • Patrick suffered from a genetic disease that altered the structure of one protein. • The protein was an enzyme. • The enzyme could potentially: • lose its ability to catalyze a reaction. • lose its ability to be regulated. • The enzyme that was mutated was involved in aerobic respiration
  18. 18. * The Stages of Aerobic RespirationThe Stages of Aerobic Respiration
  19. 19. * The Stages of Aerobic RespirationThe Stages of Aerobic Respiration Overall Reaction: C6H12O6 + 6O2 6 CO2 + 6H2O + ATP
  20. 20. Overall yield = 2 ATP and 2 NADH + H+ Steps 1-3 Steps 4-6 Steps 7-10 ATP investment steps ATP producing steps Occurs either with (aerobic) or without (anaerobic) oxygen.
  21. 21. • Glucose is not oxidized in a single step – It is broken down in a series of steps – Each step is catalyzed by an enzyme • At key points, electrons are removed – Electrons travel with a proton (as a H atom) – H atoms are transferred to an electron carrier/acceptor, NAD+ , via a reduction-oxidation (redox) reaction • NAD+ is reduced* to NADH VIP: Glycolysis Harvests Energy in a Stepwise Process
  22. 22. • Glucose is not oxidized in a single step – It is broken down in a series of steps – Each step is catalyzed by an enzyme • At key points, electrons are removed – Electrons travel with a proton (as a H atom) – H atoms are transferred to an electron carrier/acceptor, NAD+ , via a reduction-oxidation (redox) reaction • NAD+ is reduced* to NADH VIP: Glycolysis Harvests Energy in a Stepwise Process *LEO goes GER: Losing Electrons is Oxidation Gaining Electrons is Reduction
  23. 23. NADNAD++ and NADHand NADH
  24. 24. * Figure 9.6-1Figure 9.6-1 Electrons carried via NADH Glycolysis Glucose Pyruvate CYTOSOL MITOCHONDRION ATP Substrate-level phosphorylation Glycolysis Produces Pyruvate and NADH…
  25. 25. * Figure 9.6-2Figure 9.6-2 Electrons carried via NADH Electrons carried via NADH (and FADH2) Citric acid cycle Pyruvate oxidation Acetyl CoA Glycolysis Glucose Pyruvate CYTOSOL MITOCHONDRION ATP ATP Substrate-level phosphorylation Substrate-level phosphorylation The Pyruvate Feeds into the Citric Acid Cycle where…
  26. 26. * Figure 9.11Figure 9.11 Pyruvate NAD+ NADH + H+ Acetyl CoA CO2 CoA CoA CoA 2 CO2 ADP + P i FADH2 FAD ATP 3 NADH 3 NAD+ Citric acid cycle + 3 H+ …the Citric Acid Cycle Produces Even More NADH
  27. 27. * Figure 9.11Figure 9.11 Pyruvate NAD+ NADH + H+ Acetyl CoA CO2 CoA CoA CoA 2 CO2 ADP + P i FADH2 FAD ATP 3 NADH 3 NAD+ Citric acid cycle + 3 H+ …the Citric Acid Cycle Produces Even More NADH
  28. 28. Pyruvate NAD+ NADH + H+ Acetyl CoA CO2 CoA CoA CoA 2 CO2 ADP + P i FADH2 FAD ATP 3 NADH 3 NAD+ Citric acid cycle + 3 H+ …as well as some FADH2, some CO2 and more ATP FADH2 is another electron carrier (similar to NADH)
  29. 29. Let’s review what we’ve done so far… Glycolysis 1 Glucose (C6H12O6) 2 ATP + 2 NADH 2 Pyruvates (C3H3O3) Energy Yield
  30. 30. Glycolysis Citric Acid Cycle 1 Glucose (C6H12O6) 2 ATP + 2 NADH 6 CO2 2 ATP + 8 NADH + 2 FADH2 2 Pyruvates (C3H3O3) Energy Yield Remember: C6H12O6 + 6O2 6 CO2 + 6H2O + ATP Let’s review what we’ve done so far…
  31. 31. * Figure 9.6-3Figure 9.6-3 Electrons carried via NADH Electrons carried via NADH and FADH2 Citric acid cycle Pyruvate oxidation Acetyl CoA Glycolysis Glucose Pyruvate Oxidative phosphorylation: electron transport and chemiosmosis CYTOSOL MITOCHONDRION ATP ATP ATP Substrate-level phosphorylation Substrate-level phosphorylation Oxidative phosphorylation The NADH and FADH2 Feed into the Electron Transport Chain…
  32. 32. * Figure 9.15Figure 9.15 Protein complex of electron carriers (carrying electrons from food) Electron transport chain Oxidative phosphorylation Chemiosmosis I II III IV Q Cyt c FADFADH2 NADH ADP + P i NAD+ H+ 2 H+ + 1 /2O2 H+ H+ H+ 21 H+ H2O ATP The Electron Transport Chain Coordinated Transport of High Energy Electrons is Coupled to H+ Transport into the Inner Membrane Space H+ H+ H+ H+ H+ H+ ATP synthase
  33. 33. * Figure 9.15Figure 9.15 Protein complex of electron carriers (carrying electrons from food) Electron transport chain Oxidative phosphorylation Chemiosmosis ATP synthase I II III IV Q Cyt c FADFADH2 NADH ADP + P i NAD+ H+ 2 H+ + 1 /2O2 H+ H+ H+ 21 H+ H2O ATP Chemiosmosis Energy from H+ movement down the concentration gradient is used to make ATP via ATP synthase H+ H+ H+ H+ H+ H+ ATP
  34. 34. * Figure 9.15Figure 9.15 Protein complex of electron carriers (carrying electrons from food) Electron transport chain Oxidative phosphorylation Chemiosmosis I II III IV Q Cyt c FADFADH2 NADH ADP + P i NAD+ H+ 2 H+ + 1 /2O2 H+ H+ H+ 21 H+ H2O ATP Chemiosmosis Energy from H+ movement down the concentration gradient is used to make ATP via ATP synthase ATP synthase H+ H+ H+
  35. 35. Glycolysis 1 Glucose (C6H12O6) 2 ATP + 2 NADH 6 CO2 2 ATP + 8 NADH + 2 FADH2 2 Pyruvates (C3H3O3) Energy Yield Let’s Take a Final Talley… Citric Acid Cycle
  36. 36. Glycolysis 1 Glucose (C6H12O6) 6 CO2 2 Pyruvates (C3H3O3) Energy Yield Overall Reaction: C6H12O6 + 6O2 6 CO2 + 6H2O + ATP Let’s Take a Final Talley… 2 ATP + 2 NADH 2 ATP + 8 NADH + 2 FADH2 10 NADH + 2 FADH2 Citric Acid Cycle Oxidative Phosphorylation
  37. 37. Glycolysis Citric Acid Cycle 1 Glucose (C6H12O6) 6 CO2 2 Pyruvates (C3H3O3) Energy Yield Overall Reaction: C6H12O6 + 6O2 6 CO2 + 6H2O + ATP Let’s Take a Final Talley… Oxidative Phosphorylation 2 ATP + 2 NADH 2 ATP + 8 NADH + 2 FADH2 6 O2 10 NADH + 2 FADH2 6 O2 6 H2O ETC H+ gradient
  38. 38. Glycolysis Citric Acid Cycle 1 Glucose (C6H12O6) 6 CO2 2 Pyruvates (C3H3O3) Energy Yield Overall Reaction: C6H12O6 + 6O2 6 CO2 + 6H2O + ATP Let’s Take a Final Talley… Oxidative Phosphorylation 2 ATP + 2 NADH 2 ATP + 8 NADH + 2 FADH2 6 O2 10 NADH + 2 FADH2 6 O2 6 H2O ETC H+ gradient ~32 ATP Total: ~36 ATP
  39. 39. What Happens in the Absence of O2?
  40. 40. *Anaerobic RespirationAnaerobic Respiration Glycolysis Only •Make 2 ATP per glucose (rather than 32-36 ATP)
  41. 41. *Anaerobic RespirationAnaerobic Respiration Glycolysis Only •Make 2 ATP per glucose (rather than 32-36 ATP) •In yeast, ethanol is produced as a byproduct
  42. 42. *Anaerobic RespirationAnaerobic Respiration Glycolysis Only •Make 2 ATP per glucose (rather than 32-36 ATP) •In yeast, ethanol is produced as a byproduct •In animals, lactate is produced as a byproduct
  43. 43. DNA mutations can disruptDNA mutations can disrupt metabolic pathwaysmetabolic pathways *Patrick suffered from a genetic disease that altered the structure of one protein. *The protein was an enzyme. *The enzyme could potentially: *lose its ability to catalyze a reaction. *lose its ability to be regulated. *The enzyme that was mutated was involved in aerobic respiration
  44. 44. * Patrick suffered from lactate acidosisPatrick suffered from lactate acidosis • Lactate (lactic acid) and pyruvate accumulated in his blood. • Acidosis led to: o Hyperventilation o Muscle pain and weakness o Abdominal pain and nausea
  45. 45. * What happened to Patrick?What happened to Patrick? • He inherited a mutation leading to a disease called pyruvate dehydrogenase complex disease (PDCD). • Pyruvate dehydrogenase is an enzyme that converts pyruvate to acetyl CoA inside the mitochondria. • The brain depends on glucose as a fuel. PDCD degenerates gray matter in the brain. • Pyruvate accumulates, leading to lactate accumulation in the blood (lactate acidosis).
  46. 46. * Why did Patrick become paralyzed?Why did Patrick become paralyzed? A: He inherited a genetic disease that resulted in the partial loss of an enzyme necessary for aerobic breakdown of glucose. B: The enzyme that is necessary for metabolizing fats was defective. C: He was unable to synthesize muscle proteins due to defective ribosomes. D: He suffered from a severe ion imbalance due to a high salt diet.

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