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Chapter 9 Warm-Up

Chapter 9 Warm-Up. Define: Glycolysis Respiration Chemiosmosis Phosphorylation Fermentation ATP (draw and label) Electrochemical gradient FAD  FADH 2 NAD +  NADH. What is the role of phosphofructokinase? How does it “ work ” ?

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Chapter 9 Warm-Up

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  1. Chapter 9 Warm-Up Define: • Glycolysis • Respiration • Chemiosmosis • Phosphorylation • Fermentation • ATP (draw and label) • Electrochemical gradient • FAD  FADH2 • NAD+ NADH • What is the role of phosphofructokinase? How does it “work”? • Explain “glycolysis”. Where does it occur? How does it “work”?

  2. Chapter 9 Warm-Up • What is the chemical equation for cellular respiration? • Remember: OILRIG • In the conversion of glucose and oxygen to CO2 and H2O, which molecule is reduced? • Which is oxidized? • What happens to the energy that is released in this redox reaction? • NAD+ is called a(n) ________________. Its reduced form is _______.

  3. Chapter 9 Warm-Up • Why is glycolysis considered an ancient metabolic process? • Where in the cell does glycolysis occur? • What are the reactants and products of glycolysis? • Which has more energy available: • ADP or ATP? • NAD+ or NADH? • FAD+ or FADH2?

  4. Chapter 9 Warm-Up • What is 1 fact you remember from yesterday’s sugar article? • Where does the Citric Acid Cycle occur in the cell? • What are the main products of the CAC?

  5. AP Lab Warm-Up • What are 3 ways respiration can be measured? • What is the purpose of using KOH (potassium hydroxide) in this lab? • What are the Independent and Dependent Variables for Graph 5.1?

  6. Chapter 9 Warm-Up • How is the proton gradient generated? • What is its purpose? • Describe how ATP synthase works. • In cellular respiration, how many ATP are generated through: • Substrate-level phosphorylation? • Oxidative phosphorylation?

  7. Chapter 9 Warm-Up • In fermentation, how is NAD+ recycled? • What is the function of the enzyme phosphofructokinase? • You eat a steak and salad. Which macromolecule cannot be broken down to make ATP? • Explain where the fat goes when you lose weight.

  8. Chapter 9: Respiration

  9. What you need to know: • The summary equation of cellular respiration. • The difference between fermentation and cellular respiration. • The role of glycolysis in oxidizing glucose to two molecules of pyruvate. • The process that brings pyruvate from the cytosol into the mitochondria and introduces it into the citric acid cycle. • How the process of chemiosmosis utilizes the electrons from NADH and FADH2 to produce ATP.

  10. In open systems, cells require E to perform work (chemical, transport, mechanical) E flows into ecosystem as Sunlight Autotrophs transform it into chemical E O2 released as byproduct Cells use some of chemical E in organic molecules to make ATP E leaves as heat

  11. Catabolic Pathway Simpler waste products with less E Complex organic molecules Some E used to do work and dissipated as heat

  12. Respiration: exergonic (releases E) C6H12O6 + 6O2 6H2O + 6CO2 + ATP(+ heat) Photosynthesis: endergonic (requires E) 6H2O + 6CO2 + Light  C6H12O6 + 6O2

  13. Redox Reactions (oxidation-reduction) oxidation (donor) lose e- Xe- + Y  X + Ye- • Oxidation = lose e- • Reduction = gain e- C6H12O6 + 6O2 6H2O + 6CO2 + OiLRiG or LeoGer oxidation ATP reduction (acceptor) gain e- reduction

  14. Energy Harvest • Energy is released as electrons “fall” from organic molecules to O2 • Broken down into steps: Food (Glucose)  NADH  ETC  O2 • Coenzyme NAD+ = electron acceptor • NAD+ picks up 2e- and 2H+ NADH (stores E) • NADH carries electrons to the electron transport chain (ETC) • ETC: transfers e- to O2 to make H2O ; releases energy

  15. NAD+ as an electron shuttle

  16. Electron Transport Chain

  17. Substrate-Level Phosphorylation • Generate small amount of ATP • Phosphorylation: enzyme transfers a phosphate to other compounds • ADP + Pi ATP P compound

  18. Stages of Cellular Respiration • Glycolysis • Pyruvate Oxidation + Citric Acid Cycle (Krebs Cycle) • Oxidative Phosphorylation (electron transport chain (ETC) & chemiosmosis)

  19. Overview of Cellular Respiration

  20. Cellular Respiration Stage 1: Glycolysis

  21. Glycolysis • “sugar splitting” • Believed to be ancient (early prokaryotes - no O2 available) • Occurs in cytosol • Partially oxidizes glucose (6C) to 2 pyruvates (3C) • Net gain: 2 ATP +2NADH • Also makes 2H2O • No O2 required

  22. Glycolysis Stage 1: Energy Investment Stage • Cell uses ATP to phosphorylate compounds of glucose Stage 2: Energy Payoff Stage • Two 3-C compounds oxidized • For each glucose molecule: • 2 Net ATP produced by substrate-level phosphorylation • 2 molecules of NAD+ NADH

  23. Glycolysis (Summary) glucose 2 NAD+ 2 NADH + 2H+ 2 ATP 2H2O ADP P 2 pyruvate (3-C) C3H6O3

  24. Mitochondrion Structure Citric Acid Cycle (matrix) ETC (inner membrane)

  25. Cellular Respiration Stage 2: Pyruvate Oxidation + Citric Acid Cycle

  26. Pyruvate Oxidation • Pyruvate Acetyl CoA (used to make citrate) • CO2 and NADH produced

  27. Citric Acid Cycle (Krebs) • Occurs in mitochondrial matrix • Acetyl CoA Citrate  • Net gain: 2 ATP,6 NADH, 2 FADH2(electron carrier) • ATP produced by substrate-level phosphorylation CO2

  28. Summary of Citric Acid Cycle

  29. Cellular Respiration Stage 3: Oxidative Phosphorylation

  30. http://multimedia.mcb.harvard.edu/anim_mitochondria.html BioVisions at Harvard:The Mitochondria

  31. Oxidative Phosphorylation Electron Transport Chain Chemiosmosis H+ ions pumped across inner mitochondrial membrane H+ diffuse through ATP synthase (ADP  ATP) • Occurs in inner membrane of mitochondria • Produces 26-28 ATP by oxidative phosphorylation via chemiosmosis

  32. Electron Transport Chain (ETC) • Collection of molecules embedded in inner membrane of mitochondria • Tightly bound protein + non-protein components • Alternate between reduced/oxidized states as accept/donate e- • Does not make ATP directly • Ease fall of e- from food to O2 • 2H+ + ½ O2 H2O

  33. As electrons move through the ETC, proton pumps move H+ across inner mitochondrial membrane

  34. Chemiosmosis: Energy-Coupling Mechanism • Chemiosmosis = H+ gradient across membrane drives cellular work • Proton-motive force: use proton (H+) gradient to perform work • ATP synthase: enzyme that makes ATP • Use E from proton (H+) gradient – flow of H+ back across membrane

  35. Chemiosmosis couples the ETC to ATP synthesis

  36. BioFlix: Cellular Respiration

  37. oxidative phosphorylation uses which couples chemiosmosis generates proton gradient ATP uses E to produce called redox reactions H+ pumped from matrix to intermembrane space proton motive force of ETC drives in which H+ e- passed down E levels through ATP synthase to final e- acceptor O2 H2O

  38. ATP yield per molecule of glucose at each stage of cellular respiration

  39. Anaerobic Respiration: generate ATP using other electron acceptors besides O2 • Final e- acceptors: sulfate (SO4), nitrate, sulfur (produces H2S) • Eg. Obligate anaerobes: can’t survive in O2 • Facultative anaerobes: make ATP by aerobic respiration (with O2 present) or switch to fermentation (no O2 available) • Eg. human muscle cells

  40. Fermentation = glycolysis + regeneration of NAD+

  41. Glycolysis Without O2 O2 present Fermentation Respiration Release E from breakdown of food with O2 Occurs in mitochondria O2 required(final electron acceptor) Produces CO2, H2O and up to 32 ATP • Keep glycolysis going by regenerating NAD+ • Occurs in cytosol • No oxygenneeded • Creates ethanol [+ CO2]or lactate • 2 ATP (from glycolysis)

  42. Types of Fermentation Alcoholic fermentation Lactic acid fermentation Pyruvate  Lactate Ex. fungi, bacteria, human muscle cells Used to make cheese, yogurt, acetone, methanol Note: Lactate build-up does NOT cause muscle fatigue and pain (old idea) • Pyruvate  Ethanol + CO2 • Ex. bacteria, yeast • Used in brewing, winemaking, baking

  43. Various sources of fuel • Carbohydrates, fats and proteins can ALL be used as fuel for cellular respiration • Monomers enter glycolysis or citric acid cycle at different points

  44. Phosphofructokinase: • Allosteric enzyme that controls rate of glycolysis and citric acid cycle • Inhibited by ATP, citrate • Stimulated by AMP • AMP+ P + P ATP

  45. Respiration: Big Picture

  46. ENERGY aerobic cellular respiration (with O2) anaerobic (without O2) glycolysis (cytosol) mitochondria Fermentation (cytosol) pyruvate oxidation ethanol + CO2 (yeast, some bacteria) substrate-level phosphorylation citric acid cycle lactic acid (animals) ETC oxidative phosphorylation chemiosmosis

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