1. Cellular Respiration
Glycolysis
Krebs cycle
Electron transport

2. Learning check
This figure represents an overview of the different processes of cellular respiration.
Which of the following correctly identifies the different processes?
1. Glycolysis; 2. Electron transport chain; 3. Krebs cycle
1. Glycolysis; 2. Krebs cycle; 3. Electron transport chain
1. Krebs cycle; 2. Electron transport chain; 3. Glycolysis
1. Electron transport chain; 2. Glycolysis; 3. Krebs cycle

3. What would happen to the flow of electrons if oxygen were not present?
The flow of electrons would continue but at a slower rate.
The flow would cease and ATP production would stop.
The presence of oxygen would have no effect.

4. Cyanide binds strongly with the last electron carrier in the chain.
How would this affect the flow of electrons?
The flow of electrons would continue but at a slower rate.
The flow would cease and ATP production would stop.
The presence of cyanide would have no effect.

5. How many ATPs?

6. Cell Respiration Overview
Glucose:
Stores energy in the molecule
Cell respiration:
Breaks down the molecules
Extracts the contained energy
Transfers electrons (from glucose)
To hydrogen carriers (e.g., NADH)
And to make ATP
Giving off waste products (CO2 & H2O)
1st stage:
2nd & 3rd stage:
Cytoplasm
Mitochondria

7. 1st stage:
2nd stage:
3rd stage:
Glycolysis
Krebs cycle (or citric acid)
Electron transport

8. Glycolysis, in the cytoplasm
Series of steps (but 2 phases) 1.
Glucose
2 pyruvic acid molecules
As bonds in glucose are broken
Electrons (and H+ ions)
NAD+ 2.
NADH
Glucose
Is oxidized
NAD+
Is reduced
Net output is 2 ATP for each glucose molecule
But, most of the released energy carried by NADH

9. Glucose pyruvic acids
Phase one
3 carbon
6 carbon
3 carbon

10. Glycolysis, phase 1
Some ATP is used to start the ‘breakdown’ of glucose
Mitochondria
Cytoplasm
View Activity: Glycolysis

11. Glycolysis, phase 2 High energy electrons are donated To NAD+
Forming NADH

12. Glycolysis, phase 2
And, phosphate groups are transferred
ATP is made

13. In-between glycolysis & Krebs
Just before (or as) they enter the mitochondria
Pyruvic acid molecules are modified
And CO2 is released
The altered molecule is acetic acid
(…vinegar!)
Acetic acid is attached to a carrier molecule
Called coenzyme A
And forms acetyl CoA
To the mitochondrion

14. Learning check 7 3 4 2 6 8 1 5 Name molecule Name of molecule
Name the reaction
Name of molecule
What does the arrow refer to?
Where does this take place?

15. Krebs cycle, in the mitochondria
Series of reactions
Continues to break down the sugar
Present as acetic acid
Captures more energy
As NADH & FADH2
And more CO2 is released
Net output is 2 ATP for each glucose molecule
But again, most of the released energy carried by NADH

16. Krebs (citric acid) cycle & energy production
Waste:
2 CO2
Fuel:
Acetic acid 3 3
Acceptor molecule
View Activity: The Citric Acid Cycle

17. Electron Transport, in the mitochondria
Most of the ATP is produced in the ET
And, NADH & FADH donate their electrons to the ET
At the end of the chain of steps
O2 exerts a strong pull on electrons
And combines electrons & H+ ions to form H2O
The ‘downhill’ flow of electrons powers an enzyme
ATP synthase
Which produces ~ 34 ATP

18. Electron Transport An array of molecules (…proteins)
In the inner membrane of the mitochondrion
View Activity: Electron Transport

19. Electrons move from one member to the next
The energy given up pumps H+ to inner space
Matrix
Oxygen captures electrons
Hydrogens are added, water forms

20. The buildup of H+ ions give up energy
When they diffuse through a special protein
ATP synthase
Matrix
ATP synthase captures their energy
To make ATP

21. Learning check, name the numbered parts15
How many? 10 4 7 11 1 6 9 14 2 3 12 8 16 17 5 13 18

22. Learning check
Of the 3 stages of cell respiration, which produces the most ATP per glucose?
In glycolysis, _______ is oxidized and _______ is reduced.
The final electron acceptor of the electron transport chains in mitochondria is _______.

23. Learning check
Cells can harvest the most chemical energy from which of the following?
An NADH molecule
A glucose molecule
Six carbon dioxide molecules
Two pyruvic acid molecules