1. Chapter 9: Cellular Respiration and Fermentation

2. Essential Knowledge
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 ( ).

3. Cellular Respiration - Preview
Def - The process of releasing energy/ATP from food
Food - Stored energy in chemical bonds (provides fuel)
ATP - Useable energy for cellular processes
Wastes – CO2 and H2O
Mitochondrion store most of equipment needed for rxn

4. Respiration (Rs) - Equation
C6H12O6 + 6 O CO2 + 6 H2O energy (ATP or heat)
Rxn is spontaneous (-∆G)
The energy is released (exergonic) from the bonds in the org molecules
Remember: Org molecules store energy in their arrangement of atoms
Org molecules can be carbs, proteins or fats/lipids

6. Focus of Chapter Cellular Rs Other
Purpose - what is the reaction suppose to do for the cell?
Location - where does it occur?
Requirements - what is needed to make it run?
Products - what does it produce?
Other
Fermentation, Redox

7. Fuel? What is used?
Organic molecules with a large amt of hydrogen make great fuel! Why?
H becomes oxidized (only has one e-) very easily and energy is released
Remember: Carbs, fats, proteins are storage bins for e- associated with hydrogen

8. Oxidation - definitions
Loss of electrons
Loss of energy
Loss of hydrogens from carbons
Ex: Na+ (of NaCl)

9. Food and Oxidation Food (organic molecules) contain a lot of H atoms
These serve as great long-term fuels
Why?
Because H becomes easily oxidized (releases energy frequently)

10. Reduction - definitions
Gain of electrons (REDUCING + charge)
Gain of energy
Gain of hydrogens to carbons
Ex: O is often reduced!
Why?
Because electrons are pulled closer to O

11. Redox reactions

12. Equation for Rs Oxidized Reduced
C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy (ATP/heat) General Redox Equation: Xe- + Y  X + Ye-
Reduced

13. Redox reactions Involves transfer of e- and energy release
Sometimes doesn’t involve complete transfer
Red and Oxd reactions are usually paired or linked together.
Why?Because e- transfer requires donor and acceptor
Many of the reactions will be done by phosphorylation
Redox video

14. Phosphorylation Adding a phosphate group to a molecule Two types:
Ex: ATP cycle (add P to ADP = ATP)
Two types:
Oxidative AND substrate-level
The phosphate group adds “energy” to the molecule for chemical reactions (think ATP cycle)
Endergonic rxn

15. Phosphorylation

16. Cell Respiration – 3 parts
1. Glycolysis
2. Krebs Cycle
3. Electron Transport Chain
**Use page 167 as a starting point:
Cellular Respiration - A Preview

18. STEP 1 Glycolysis Glyco- glucose -lysis: to split
Formula for glucose: C6H12O6
Universal step in all Rs types.
Likely the earliest type of cell energy processes
Overview:
Glucose splits into 2 3-C sugars (then oxidizes to form pyruvate)

19. Glycolysis Function - To split glucose and produce NADH and ATP
ATP made by substrate-level phosphorylation
Enzyme transfers phosphate group from substrate/reactant to ADP to make ATP
Location – Cytoplasm of the cell

21. Electron Carrier Compounds
Molecules that transport or shuttle electrons within the cell
Exist in two forms:
Oxidized (ox)
Reduced (red)
Ex: NAD and FAD

22. NAD Nicotinamide Adenine Dinucleotide NAD+ + 2 e- NADH
NAD+ = oxidized form
NADH = reduced form*
*Reduced by e- from food oxidation

24. Glycolysis Requirements
Glucose
2 ATP
4 ADP
2 NAD+
Can occur with or without O2

25. Notice: No CO2 made during this step!
Glycolysis Intro
Glycolysis - Products
2 Pyruvic Acids (a 3-Carbon acid)
2 ADP, 4 ATP, 2 NADH
NET RESULT:
2 ATP per glucose
2 NADH
2 pyruvate
H2O
Notice: No CO2 made during this step!

27. STEP 2 Krebs Cycle Oxidizes fuel from pyruvate molecules Also called:
Remember? Pyruvate formed during glycolysis
Also called:
Citric Acid Cycle
Tricarboxylic Acid Cycle

28. Krebs Cycle Function: Oxidize pyruvic acid (to make CO2 )
Produces: NADH and FADH2
Location: Mitochondria matrix
Before Krebs: Acetyl CoA must be formed
Acetyl CoA is needed to actually start Krebs

29. Pyruvate moved into mito?
Why? How?
Pyruvate is moved into mitochondria (from cytoplasm)
Why? This is where the 2nd step occurs (specific enzymes are in mito)
Serves as a checkpoint
Uses active transport and transport proteins.
Why? Pyruvate is a charged molecule!

30. Formation of Acetyl CoA

31. Krebs Cycle Requirements
Pyruvic acid (3C acid)
Acetyl coenzyme A
4 NAD+
1 ADP
1 FAD
Double this list for each glucose

32. LOADS of energy stored in these molecules
Krebs Cycle Intro
Krebs Cycle Products
3 CO2
Acetyl CoA
4 NADH
1 FADH2
1 ATP
Double this list for each glucose
Made from pyruvate
LOADS of energy stored in these molecules

34. Krebs Cycle notes Notice: Does NOT require O2
Only 1 ATP made per cycle
Produces most of the cell's energy in the form of NADH and FADH2
Does NOT require O2

35. Comment about ATP
The ATPs produced directly in Krebs Cycle and Glycolysis are by:
Substrate-level phosphorylation
The P group is transferred from a substrate to ADP
Making ATP

36. At this point…
After the Krebs and glycolysis cycles, the cell has made a total of 4 ATP.
Remember: some ATP had to be used to power the cycles.
Most energy (at this point) comes from NADH and FADH2

37. Electron Transport System
STEP 3
ETC/S or Electron Transport Chain
This is a collection of proteins that are structurally linked
Located in inner membrane of mito
Folding of mito (cristae) allows for lots of places (large surface area!) for ETC to occur

38. ETC/S Uses sets of Cytochromes
Fe (Iron)-containing proteins to pass electrons
The Cytochromes alternate between Red and Ox forms and pass electrons down to O2
Remember: LEO, GER; LEO the lion goes GER
Losing Electrons is Oxidation; Gaining Electrons is Reduction

39. As e- moves down the ETC, free energy decreases

40. ETC/S Function: Convert NADH and FADH2 into ATP
Location: Mitochondria cristae/folds

41. ETC Requirements NADH or FADH2 ADP O2
We finally see the need/requirement of Oxygen

42. ETC Products NAD+ and FAD ATP (LOTS!!!) H2O
Remember: Water was also produced during glycolysis
ETC explanation

43. ETC - ATP Yields
Each NADH  3 ATP
Each FADH2  2 ATP
TOTAL: 34 ATP

44. Chemiosmotic Hypothesis
ETC energy is used to move H+ (protons) across the mito/cristae membrane
ATP is generated as the H+ diffuse back into the matrix

46. ATP Synthase Enzyme An enzyme that uses the flow of H+ to make ATP
Works like an ion pump in reverse, or like a waterwheel under the flow of H+ “water”
Power source:
H+ concentration difference on opposite sides of mitochondrial membrane

47. Oxidative Phosphorylation
ATP synthase uses oxidative phosphorylation to make ATP during ETC
Uses H ions to make ATP and water (using Oxygen)

48. ATP Synthase

49. Alcoholic Fermentation
Done by yeast
A kind of fungus
Used in brewing beer, winemaking, and baking
CO2 bubbles generated give:
Bread a rising effect
Wine/Beer the carbonated effect

50. Alcoholic Fermentation
Uses only Glycolysis
An incomplete oxidation - energy is still left in the products (alcohol)
Does NOT require O2
Produces ATP (when O2 is not available)

51. Alcohol

52. Lactic Acid Fermentation
Uses only Glycolysis
An incomplete oxidation - energy is still left in the products (lactic acid)
Does NOT require O2
Produces ATP (when O2 is not available)

53. Lactic acid

54. Lactic Acid Fermentation
Done by human muscle cells under oxygen debt
Lactic Acid is a toxin and can cause soreness and stiffness in muscles
Oxygen intake can’t keep up with sugar breakdown
Used in dairy industry (yogurt/cheese)
Also used to produce methanol and acetone

55. Fermentation - Summary
Way of using up NADH so Glycolysis can still run
Provides ATP to a cell even when O2 is absent

56. Fermentation
*Alcoholic OR
*Lactic acid

57. Aerobic vs Anaerobic Aerobic - Rs with O2 Anaerobic - Rs without O2
Aerobic - All three Rs steps
Anaerobic - Glycolysis only

58. Strict vs. Facultative Strict - can only do Rs this one way
Either aerobic OR anaerobic-NOT both!
Facultative - can switch types depending on O2 availability
Ex - yeast

59. Question??
Since yeast can do both aerobic and anaerobic Rs, which is the better process if given a choice?
Hint: Check the ATP yields from both processes.

60. ATP yields by Rs type
Anaerobic - Glycolysis only gets 2 ATPs per glucose
Aerobic - Glycolysis, Krebs, and ETC.
Generates many more ATPs per glucose.

61. Aerobic ATP yield Glycolysis - 2 ATPS, 2 NADHs
Krebs - 2 ATPS, 8 NADHs, 2 FADH2
Each NADH = 3 ATP
Each FADH2 = 2 ATP

62. Aerobic ATP Sum Max = 38 ATPs per glucose 10 NADH x 3 = 30 ATPs
2 FADH2 x 2 = ATPs
2 ATPs (Gly) = ATPs
2 ATPs (Krebs) = 2 ATPs
Max = 38 ATPs per glucose

63. However...
Some energy (2 ATP) is used in shuttling the NADH and pyruvate from Glycolysis into the mitochondria
Actual ATP yield ~ 36/glucose

64. Yeast Would rather do aerobic Rs;
This has 18x more energy per glucose than anaerobic
But, anaerobic will keep you alive if oxygen is not present.

65. Importance of Rs Convert food to ATP
Living orgs use ATP to fuel body processes
Ex: reproduction, cell division
Provides materials for use in other cellular pathways

66. Other Respiration Items of Importance
Alcohol Industry - almost every society has a fermented beverage
Baking Industry - many breads use yeast to provide bubbles to raise the dough

68. Alcohol Matching Game!
Sugar Cane Gin Barley Rum Grapes Wine Juniper Cones Vodka Agave Leaves Beer Rice Tequila Potatoes Saki

69. Summary Identify the basic chemical equation for cellular respiration.
Identify the main reaction sequences of cellular respiration.
Recognize the location, function, requirements, and products, for each cellular respiration reaction.
Recognize and be able to discuss the chemiosmotic model for ATP generation.
Recognize the reactions and importance of fermentation.
Contrast and compare aerobic and anaerobic respiration.
Identify the biological and commercial importances of respiration.

70. Exclusion Statements
You do NOT need to memorize the steps in glycolysis and the Krebs cycle, the structures of the molecules, or the names of the enzymes that are involved.
You do NOT need to memorize the names of the specific electron carriers in the electron transport chain (ETC).