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-
C6H12O O2  6H2O + 6CO2 +
reduction (acceptor) gain e-
OiLRiG or LeoGer
oxidation
ATP
reduction

15. Food (Glucose)  NADH  ETC  O2
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

16. NAD+ as an electron shuttle

17. Electron Transport Chain

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

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

20. Overview of Cellular Respiration

21. Cellular Respiration
Stage 1: Glycolysis

22. 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

23. 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

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

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

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

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

30. 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

32. Summary of Citric Acid Cycle

33. Stage 3: Oxidative Phosphorylation
Cellular Respiration
Stage 3: Oxidative Phosphorylation

34. BioVisions at Harvard: The Mitochondria
BioVisions at Harvard: The Mitochondria

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

36. 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

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

38. 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

39. Chemiosmosis couples the ETC to ATP synthesis

40. BioFlix: Cellular Respiration

41. H+ pumped from matrix to intermembrane space
oxidative phosphorylation
uses
generates
chemiosmosis
which couples
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

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

43. 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

44. Fermentation = glycolysis + regeneration of NAD+

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

46. Types of Fermentation Pyruvate  Ethanol + CO2 Ex. bacteria, yeast
Alcoholic fermentation
Lactic acid fermentation
Pyruvate  Ethanol + CO2
Ex. bacteria, yeast
Used in brewing, winemaking, baking
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)

47. 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

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

49. Respiration: Big Picture

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

51. Glycolysis & Citric Acid Cycle

52. Oxidative Phosphorylation
Electron Transport Chain
Chemiosmosis