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 5 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. 9.1 Catabolic pathways yield energy by oxidizing organic fuels
2.A.1 All living systems require constant input of free energy
Life requires a highly ordered system
evidence of student learning is demonstrated understanding of each of the following
Order is maintained by constant free energy input into the system
Loss of order or free energy flow results in death
Increased disorder or entropy are offset by biological processes that maintain or increase order.

11. b. Living systems do not violate the second law of thermodynamics which states that entropy increases over time.
Order is maintained by coupling cellular processes that increase entropy (and so have negative changes in free energy) with those that decrease entropy (and so have positive changes in free energy)
Energy input must exceed free energy lost to entropy to maintain order and power cellular processes.
Energetically favorable exergonic reactions such as ATP ADP, that have a negative charge in free energy can be used to maintain or increase order in a system by being coupled with reactions that have a positive free energy change.

12. Krebs cycle, Glycolysis, Calvin cycle, Fermentation
c. Energy-related pathways in biological systems are sequential and may be entered at multiple points in the pathway
Krebs cycle, Glycolysis, Calvin cycle, Fermentation
d. Organisms use free energy to maintain organization, grow, and reproduce
Organisms use various strategies to regulate body temperature and metabolism
a. Endothermy (the use of thermal energy generated by metabolism to maintain homeostatic body temperatures)
b. Ectothermy (the use of external thermal energy to help regulate and maintain body temperature)
c. Elevated floral temperatures in some plant species

13. Reproduction requires free energy (more)
Relationship between metabolic rate and organism size (more)
Excess acquired free energy vs required free energy expenditure results in energy storage or growth
Insufficient acquired free energy vs required free energy expenditure results in loss of mass and ultimately the death of an organism
Changes in free energy availability can result in changes in population size
Changes in free energy availability can result in disruptions to an ecosystem

14. Learning Objective
LO 2.1 The student is able to explain how biological systems use free energy based on empirical data that all organisms require constant energy input to maintain organization, to grow and to reproduce. (see sp6.2)
LO 2.2 The students is able to justify a scientific claim that free energy is required for living systems to maintain organization to grow or to reproduce, but that multiple strategies exist in different living systems (see sp 6.1)
LO 2.3 The student is able to predict how changes in free energy availability affect organisms, populations and ecosystems (see sp6.4)

15. 9.1 Catabolic pathways yield energy by oxidizing organic fuels
2.A.1 All living systems require constant
input of free energy
2.A.2 Organisms capture and store free
energy for use in biological processes

16. 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

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

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

19. 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

21. 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

22. NAD+ as an electron shuttle

23. Electron Transport Chain

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

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

26. Overview of Cellular Respiration

27. 9.2 Cellular Respiration Stage 1: Glycolysis
2.A.1 All living systems require constant input of free energy
2.A.2 Organisms capture and store free energy for use in biological processes

28. 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

29. 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

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

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

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

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

36. 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

38. Summary of Citric Acid Cycle

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

40. BioVisions at Harvard: The Mitochondria
BioVisions at Harvard: The Mitochondria

41. 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)

42. 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

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

44. 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

45. Chemiosmosis couples the ETC to ATP synthesis

46. BioFlix: Cellular Respiration

47. 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

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

49. 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

50. Fermentation = glycolysis + regeneration of NAD+

51. 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

52. 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)

53. 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

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

55. Respiration: Big Picture

56. 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

57. Glycolysis & Citric Acid Cycle

58. Oxidative Phosphorylation
Electron Transport Chain
Chemiosmosis