1. Chapter 9: Respiration

2. 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.

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

4. Overview of Cellular Respiration

5. Cellular Respiration
Stage 1: Glycolysis

6. Glycolysis 6C 3C Breaking down glucose glucose      pyruvate 2x
ancient pathway which harvests energy
where energy transfer _______________________________________
transfer energy from organic molecules to ATP
still is starting point for ________ cellular respiration
but it’s _____________________________
generate only 2 ATP for every 1 glucose
occurs in ___________________
glucose      pyruvate 2x 6C 3C
Why does it make sense that this happens in the cytosol?
Who evolved first?
That’s not enough ATP for me!

7. TURN & TALK
Why does it make sense EVOLUTIONARILY that Glycolysis occurs in cytoplasm?

8. Evolutionary perspective
Enzymes of glycolysis are “well-conserved”
_____________________________
first cells had no organelles
__________________________ atmosphere
life on Earth first evolved without free oxygen (O2) in atmosphere
energy had to be captured from organic molecules in absence of O2
Prokaryotes that evolved glycolysis are ________________ of all modern life
ALL cells still utilize glycolysis
The enzymes of glycolysis are very similar among all organisms. The genes that code for them are highly conserved.
They are a good measure for evolutionary studies. Compare eukaryotes, bacteria & archaea using glycolysis enzymes.
Bacteria = 3.5 billion years ago
glycolysis in cytosol = doesn’t require a membrane-bound organelle
O2 = 2.7 billion years ago
photosynthetic bacteria / proto-blue-green algae
Eukaryotes = 1.5 billion years ago
membrane-bound organelles!
Processes that all life/organisms share:
Protein synthesis
Glycolysis
DNA replication
You mean we’re related? Do I have to invite them over for the holidays?

9. Glycolysis Overview “sugar splitting”
Believed to be ancient (early prokaryotes - no O2 available)
Location: cytosol
Reaction:
Partially oxidizes glucose (___C) to 2 pyruvates (___C)
Consumes: 2 ATP
Net Yield: ___________+ ___________
Also makes _________________ (waste)
No ________ required

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

11. Substrate-Level Phosphorylation
Generate small amount of ATP
Phosphorylation: enzyme transfers a _______________________ to other compounds
ADP (_______________) + Pi  ATP P
compound

13. Is that all there is? Not a lot of energy…
for 1 billon years+ this is how life on Earth survived
no O2 = ___________________________________________
only harvest 3.5% of energy stored in glucose
more carbons to strip off = more energy to harvest O2
glucose     pyruvate O2
So why does glycolysis still take place? 6C 2x 3C O2
Hard way to make a living! O2 O2

14. How is NADH recycled to NAD+?
with oxygen
aerobic respiration
without oxygen
anaerobic respiration
“fermentation”
Another molecule must accept H from NADH
pyruvate
H2O
NAD+
CO2
recycle NADH
NADH O2
NADH
acetaldehyde
acetyl-CoA
NADH
NAD+
NAD+
lactate
lactic acid fermentation
which path you use depends on who you are…
Krebs
cycle
ethanol
alcohol fermentation

15. Fermentation (anaerobic)
____________, ___________ 1C 3C 2C
pyruvate  _______ + CO2
NADH
NAD+
back to glycolysis
beer, wine, bread
_____________, some fungi
Count the carbons!!
Lactic acid is not a dead end like ethanol. Once you have O2 again, lactate is converted back to pyruvate by the liver and fed to the Kreb’s cycle.
pyruvate  ____________ 3C
NADH
NAD+
back to glycolysis
cheese, anaerobic exercise (no O2)

16. Alcohol Fermentation pyruvate  ethanol + CO2 Dead end process
bacteria yeast
Alcohol Fermentation
recycle NADH 1C 3C 2C
pyruvate  ethanol + CO2
NADH
NAD+
back to glycolysis
Dead end process
at ~12% ethanol, kills yeast
can’t reverse the reaction
Count the carbons!

17. Lactic Acid Fermentation
animals some fungi
Lactic Acid Fermentation
recycle NADH O2
pyruvate  lactic acid 3C 
NADH
NAD+
back to glycolysis
Reversible process
once O2 is available, lactate is converted back to pyruvate by the liver
Count the carbons!

18. Pyruvate is a branching point
____________
anaerobic respiration
mitochondria
__________________
aerobic respiration

19. Glycolysis (Summary)
2 NAD+ P
ADP
2 NADH + 2H+
2 ATP
(3-C)
C3H6O3

20. Stage 2: Pyruvate Oxidation + Citric Acid Cycle [Krebs Cycle]
Cellular Respiration
Stage 2: Pyruvate Oxidation + Citric Acid Cycle [Krebs Cycle]

21. Mitochondria — Structure
___________________ membrane energy harvesting organelle
smooth ________________ membrane
highly __________________ inner membrane
Called _____________________
intermembrane space
fluid-filled space between membranes
_________________
inner fluid-filled space
DNA, ribosomes
enzymes
free in matrix & membrane-bound
intermembrane
space
inner
membrane
outer
matrix
cristae
mitochondrial DNA
What cells would have a lot of mitochondria?

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

23. Pyruvate Oxidation

24. Pyruvate Oxidation
2 Pyruvate  2 _______________________ (used to make citrate)
Produces: 2)______ and 2NADH

25. [ ] Oxidation of pyruvate Pyruvate enters mitochondrial matrix
3 step oxidation process
releases 2 CO2 (count the carbons!)
reduces 2 NAD  2 NADH (moves e-)
produces 2 acetyl CoA
Acetyl CoA enters _________________ [ 2x ]
pyruvate    acetyl CoA + CO2 3C
NAD 2C 1C
Where does the CO2 go?
Exhale!
CO2 is fully oxidized carbon == can’t get any more energy out it
CH4 is a fully reduced carbon == good fuel!!!

26. Krebs cycle 1937 | 1953 aka Citric Acid Cycle
in _____________________________
8 step pathway
each catalyzed by specific enzyme
step-wise catabolism of 6C citrate molecule
Evolved later than glycolysis
does that make evolutionary sense?
bacteria 3.5 billion years ago (glycolysis)
free O2 2.7 billion years ago (photosynthesis)
eukaryotes 1.5 billion years ago (aerobic respiration = ________________  mitochondria)
Hans Krebs
The enzymes of glycolysis are very similar among all organisms. The genes that code for them are highly conserved.
They are a good measure for evolutionary studies. Compare eukaryotes, bacteria & archaea using glycolysis enzymes.
Bacteria = 3.5 billion years ago
glycolysis in cytosol = doesn’t require a membrane-bound organelle
O2 = 2.7 billion years ago
photosynthetic bacteria / proto-blue-green algae
Eukaryotes = 1.5 billion years ago
membrane-bound organelles!
Processes that all life/organisms share:
Protein synthesis
Glycolysis
DNA replication

27. Citric Acid Cycle (Krebs)
Location: Occurs in mitochondrial matrix
Reaction:
Acetyl CoA  Citrate  released
Net Yield:
___ATP, ___ NADH, ___ FADH2 (electron carrier)
ATP produced by ___________________________
CO2

28. Count the carbons! x2 3C 2C 4C 6C 4C 6C 5C 4C 4C 4C
pyruvate 3C 2C
acetyl CoA
citrate 4C 6C 4C 6C
This happens __________ for each glucose molecule
oxidation of sugars
CO2
A 2 carbon sugar went into the Krebs cycle and was taken apart completely. Two CO2 molecules were produced from that 2 carbon sugar. Glucose has now been fully oxidized!
But where’s all the ATP??? x2 5C 4C
CO2 4C 4C

29. Count the electron carriers!
pyruvate 3C 2C
acetyl CoA
NADH
NADH
citrate 4C 6C 4C 6C
reduction of electron carriers
This happens twice for each glucose molecule
CO2
Everytime the carbons are oxidized, an NAD+ is being reduced.
But wait…where’s all the ATP??
NADH x2 5C 4C
FADH2
CO2 4C 4C
NADH
ATP

30. Whassup? So we fully oxidized glucose C6H12O6  CO2
& ended up with _______!
What’s the point?

31. What’s so important about electron carriers?
Electron Carriers = ___________ Carriers H+
Krebs cycle produces large quantities of electron carriers
NADH
FADH2
go to __________ _______________!
ADP + Pi
ATP
What’s so important about electron carriers?

32. Energy accounting of Krebs cycle2x
4 NAD + 1 FAD
4 NADH + 1 FADH2
pyruvate          CO2
1 ADP
1 ATP 3C 3x 1C
ATP
Net gain = 2 ATP
= 8 NADH + 2 FADH2

33. Value of Krebs cycle?
If the yield is only 2 ATP then how was the Krebs cycle an adaptation?
value of NADH & FADH2
electron carriers & H carriers
reduced molecules move _____________________
to be used in the ___________________________
like $$ in the bank

34. Summary of Citric Acid Cycle

35. REVIEW: TURN & TALK
Explain “glycolysis”. Where does it occur? How does it “work”?
What is the chemical equation for cellular respiration?
Which has more energy available:
ADP or ATP?
NAD+ or NADH?
FAD+ or FADH2?
Where does the Citric Acid Cycle occur in the cell?

36. HOMEWORK
Watch the video “Cellular Respiration” from Bozeman Science
Take detailed notes

37. POGIL: Glycolysis and Krebs Cycle

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

39. 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)

40. 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

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

42. 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

43. Chemiosmosis couples the ETC to ATP synthesis

44. 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

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

46. BioFlix: Cellular Respiration

47. 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

48. Fermentation = glycolysis + regeneration of NAD+

49. 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

50. Types of Fermentation Pyruvate  Ethanol + CO2 Ex. bacteria, yeast
Alcohol 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 causes muscle fatigue and pain (old idea)

51. 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

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

53. Respiration: Big Picture

54. 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

55. Glycolysis & Citric Acid Cycle

56. Oxidative Phosphorylation
Electron Transport Chain
Chemiosmosis

57. What’s the Difference? Substrate-level phosphorylation
Oxidative phosphorylation
Add Pi from one compound to ADP directly
Energy comes from the chemical reaction itself
“no middle man”
Uses:
Glycolysis
Krebs Cycle
Uses a “middle man” = NADH and FADH and the pumping of electrons to generate an electrochemical gradient to make ATP
Pi come from a pool of phosphates
Uses:
ETC + Chemiosmosis

59. Worksheet Practice

60. Quizlet https://quizlet.com/_3whks7
Play/Review with the flashcards first
Then select 1 game to play either alone or with a partner
Record your time: ______

61. Bean Brew…an Investigative Case
Close Read
? And !
Highlight key vocab terms
Work to complete the questions throughout the investigation (Parts I-II)in your lab groups.
Answer in complete sentences in the packets.
Use the textbook to refer to the indicated diagrams in ch. 7, 8, and 9.
Choose either Part IV or V to complete at home. Due date = Monday Nov. 6

62. “The Mystery of the Seven Deaths”
Read the Case Study and answer the questions.
Discuss with someone near you if you aren’t sure!
Write your answers in the white space but be sure to use COMPLETE sentences that clearly address the question.