1. Cellular Respiration Review

2. Cellular Respiration 1. Define cellular respiration.
A process that releases energy from food, such as the simple sugar glucose, when there is oxygen present.
2. Name several organisms that undergo cellular
respiration
Nearly all living things undergo cellular respiration*.
Exceptions include a few microscopic marine animals (Loricifera) and some bacteria.

3. Cellular Respiration 3. Using chemical formulas, write the balanced
equation for cellular respiration.
6O2 + C6H12O CO H2O + Energy
4. Now write out the equation using words.
Oxygen + Glucose yields Carbon dioxide + Water + Energy

4. Cellular Respiration 5. What organelle in eukaryotes is involved in
The mitochondrion
6. What is a common analogy for mitochondria?
Mitochondria are sometimes called “cellular power plants” or the “powerhouses” of the cell.

5. Cellular Respiration 7. Where in eukaryotes are mitochondria found?
In all cells. Depending on the organism and the type of cell, the number of mitochondria can range from one to thousands.
Root tip of a corn plant.
Mitochondria

6. Cellular Respiration 8. What kind of human cells contain the most
and least number of mitochondria?
Skeletal Muscle
Cells that require the most energy contain the highest number of mitochondria. The cells of the brain, skeletal muscle, heart muscle, and the eye contain the greatest number (as many as 10,000 per cell) while the skin cells, which do not require much energy, contain only a few hundred.

7. Endoplasmic reticulum
Cellular Respiration
9. Identify the mitochondria in this micrograph of
a human pancreatic cell.
Pancreas
The pancreas secretes insulin in response to glucose levels in the blood.
Pancreas cell
Nucleus
Nucleolus
Endoplasmic reticulum
Mitochondria

8. Cellular Respiration
Identify the following structures of the mitochondrion. 10 11 12 13

9. Cellular Respiration
Identify the following structures of the mitochondrion.
Outer membrane 11 12 13

10. Cellular Respiration
Identify the following structures of the mitochondrion.
Outer membrane
Inner membrane 12 13

11. Cellular Respiration
Identify the following structures of the mitochondrion.
Outer membrane
Inner membrane
Inner membrane space 13

12. Cellular Respiration
Identify the following structures of the mitochondrion.
Outer membrane
Inner membrane
Inner membrane space
Matrix

13. Cellular Respiration 14. What are the three main stages of
Glycolysis (Converting glucose to pyruvic acid)
Glucose
Two pyruvic acid
The Krebs cycle (Breaking down pyruvic acid into CO2)
Pyruvic acid
Three Carbon dioxide
Electron Transport (Making lots of ATP)
ATP

14. Cellular Respiration 15. Where in the mitochondrion does each
stage of cellular respiration occur?
Glycolysis takes place in the cell’s cytoplasm outside the mitochondrion
The Krebs cycle occurs in the matrix
The Electron Transport Chain operates in the inner membrane.

15. Cellular Respiration 16. What happens during glycolysis?
Four enzymes are used to break glucose into two molecules of G3P*
Glucose
Two ATP are invested to get this done.
ATP
ATP
Two G3P
Five enzymes then convert G3P into pyruvic acid**
ATP
Four ATP are produced.
Electron carriers
Two pyruvic acid
ATP
Two electron carriers pick up electrons during the process
A net of two ATP are made.
*G3P is Glyceraldehyde-3-phosphate ** Pyruvic acid is known as pyruvate

16. Cellular Respiration 17. What happens in the Krebs cycle?
Pyruvic acid enters the mitochondrial matrix where it will enter the Krebs cycle.
Matrix
Mitochondrion
Oxaloacetate
Acetyl CoA
Enzymes
Pyruvic acid
Electron carriers

17. Cellular Respiration 17. What happens in the Krebs cycle?
Here pyruvic acid will interact with enzymes and other molecules.
Matrix
Mitochondrion
Oxaloacetate
Acetyl CoA
Enzymes
Electron carriers

18. Cellular Respiration 17. What happens in the Krebs cycle?
After a series of chemical reactions, three carbon dioxide molecules are produced.
Matrix
Mitochondrion
Enzymes
Electron carriers

19. Cellular Respiration 17. What happens in the Krebs cycle?
In addition, a molecule of ATP is generated…
Matrix
Mitochondrion
Enzymes
ATP
Electron carriers

20. Cellular Respiration 17. What happens in the Krebs cycle?
Electron carriers* also pick up excess electrons.
Matrix
Mitochondrion
Enzymes
Electron carriers
ATP
* Electron carriers NAD+ and FAD

21. Cellular Respiration 17. What happens in the Krebs cycle?
Electron carriers* also pick up excess electrons. They then travel to the inner membrane.
Matrix
Mitochondrion
Enzymes
Electron carriers
Electron carriers
Electron carriers
Electron carriers
Electron carriers
ATP
* Electron carriers NAD+ and FAD

22. Cellular Respiration 18. What do the carriers do with their electrons?
The electron carriers drop off their electrons at the inner membrane.
Matrix
Mitochondrion
Electron carriers
Electron carriers
Electron carriers
Enzymes
Electron carriers
Electron carriers
* Electron carriers NAD+ and FAD

23. Cellular Respiration 18. What do the carriers do with their electrons?
The carriers then return to the matrix to pick up more electrons while other molecules are recycled.
Matrix
Mitochondrion
Electron carriers
Electron carriers
Electron carriers
Enzymes
Oxaloacetate
Acetyl CoA
Electron carriers
Electron carriers
* Electron carriers NAD+ and FAD

24. Cellular Respiration
19. What happens to the electrons at the inner membrane?
At the inner membrane, the electron carriers attach themselves to membrane proteins.
Electron carriers
H + ions
Matrix
Inner membrane
Inner membrane space
ATP Synthase
Cytoplasm
Outer membrane

25. Cellular Respiration
19. What happens to the electrons at the inner membrane?
The electrons are then passed to the protein.
H + ions
Matrix
Inner membrane
Electron carriers
Inner membrane space
ATP Synthase
Cytoplasm
Outer membrane

26. Cellular Respiration
19. What happens to the electrons at the inner membrane?
Some of the energy from the transfer of electrons is used to pump hydrogen ions (H+) into the inner membrane space.
H + ions
Matrix
Inner membrane
Inner membrane space
ATP Synthase
Cytoplasm
Outer membrane

27. Cellular Respiration
19. What happens to the electrons at the inner membrane?
Meanwhile, the shuttle protein ubiquinone moves in to pick up the electrons.
H + ions
Matrix
Inner membrane
Inner membrane space
ATP Synthase
Ubiquinone
Cytoplasm
Outer membrane

28. Cellular Respiration
19. What happens to the electrons at the inner membrane?
The shuttle will move the electrons to the next protein.
H + ions
Matrix
Inner membrane
Inner membrane space
ATP Synthase
Ubiquinone
Cytoplasm
Outer membrane

29. Cellular Respiration
19. What happens to the electrons at the inner membrane?
Some of the energy from the transfer of electrons will be used to pump more H+ ions across the membrane.
H + ions
Matrix
Inner membrane
Inner membrane space
ATP Synthase
Cytochrome C
Cytoplasm
Outer membrane

30. Cellular Respiration
19. What happens to the electrons at the inner membrane?
The electrons will then be shuttled by cytochrome c to their last protein.
H + ions
Matrix
Inner membrane
Inner membrane space
ATP Synthase
Cytochrome C
Cytoplasm
Outer membrane

31. Cellular Respiration
19. What happens to the electrons at the inner membrane?
Again, H+ ions will be pumped across the membrane.
H + ions
Matrix
Inner membrane
Inner membrane space
ATP Synthase
Cytoplasm
Outer membrane

32. Cellular Respiration
19. What happens to the electrons at the inner membrane?
Finally, an oxygen atom will pick up the two electrons along with two H+ ions to form a molecule of water.
H + ions
Matrix
Inner membrane O2
Inner membrane space
ATP Synthase
H2O
Cytoplasm
Outer membrane

33. Cellular Respiration 20. Where does the water molecule go?
Water will exit the mitochondrion
H + ions
Matrix
Inner membrane
Inner membrane space
ATP Synthase
H2O
Cytoplasm
Outer membrane

34. Cellular Respiration
21. How will the pH in the inner membrane space change?
As more H+ is pumped into the inner membrane space, the space becomes more acidic. This causes the pH to drop.
H + ions
Matrix
Inner membrane
pH 7.8
Inner membrane space
ATP Synthase
Cytoplasm
pH 7.2
Outer membrane

35. Cellular Respiration
22. How does the concentration of H+ ions in the matrix
compare to that in the inner membrane space?
There are more H+ ions in the inner membrane space, which sets up a concentration gradient.
H + ions
Matrix
Inner membrane
High H+ Concentration
Low H+ Concentration
Inner membrane space
ATP Synthase
Cytoplasm
Outer membrane

36. Cellular Respiration
23. In which direction is the concentration gradient?
The H+ ions will flow down their concentration gradient from the inner membrane space toward the matrix.
H + ions
Matrix
Inner membrane
High H+ Concentration
Low H+ Concentration
Inner membrane space
ATP Synthase
Gradient
Cytoplasm
Outer membrane

37. Cellular Respiration
24. Through what membrane protein will the H+ ions flow?
The H+ ions will flow through an enzyme called ATP synthase. This flow provides the energy needed to generate ATP from ADP.
H + ions
Matrix
Inner membrane
ATP Synthase
ATP P
ADP
Cytoplasm
Outer membrane

38. Cellular Respiration
25. About how many ATP can be generated by cellular
respiration from one glucose molecule?
One glucose molecule yields about 36 to 38 ATP
(2 ATP from glycolysis, 2 ATP from the Krebs cycle, and 32 to 34 ATP from the electron transport chain).
ATP
H + ions
Matrix
ATP
Inner membrane
Inner membrane space
ATP Synthase
Cytoplasm
Outer membrane