2. CELLULAR
RESPIRATION

3. Photosynthesis: REVIEW
Previously, we learned that photosynthesis
takes place in the chloroplasts
In the ‘light reactions’, solar energy is captured
by photosystems on the thylakoid membrane and used to attach phosphate groups to
energy-carrying molecules like ATP.

4. This completes the equation for photosynthesis:
Photosynthesis: REVIEW
This completes the equation for photosynthesis:
6 CO2 + 6 H C6H12O6 + 6 O2
In the CALVIN CYCLE, the ATP and NADPH made in the light reactions are used to power the assembly of sugars in the stroma, the fluid-filled interior of the chloroplasts.

5. Photosynthesis: REVIEW
This completes the equation for photosynthesis:
6 CO2 + 6 H C6H12O6 + 6 O2
So now we have energy stored in the form of
sugars. Very nice, but what if plants (or, for that matter, people) want to release that energy?
THEY MUST USE A DIFFERENT PATH…..!

6. CELLULAR RESPIRATION ! Next, we’ll need another organelle to do these
FIRST, WE REVERSE THE EQUATION:
6 CO2 + 6 H C6H12O6 + 6 O2
Next, we’ll need another organelle to do these
reactions in! Not chloroplasts this time, but
instead another organelle with its own DNA….

7. Mitochondria:

8. Mitochondria:

9. Mitochondria: have complex folded inner membranes
(cristae), increasing their surface area

10. Mitochondria: have complex folded inner membranes
(cristae), increasing their surface area
have a fluid-filled interior (the matrix)

11. Mitochondria: have complex folded inner membranes
(cristae), increasing their surface area
have a fluid-filled interior (the matrix)
act like combustion chambers in an engine,
a ‘safe’ place to ‘burn’ fuel with oxygen

12. A Combustion Chamber?

13. A Combustion Chamber? LET’S COMPARE!
A gasoline engine
and a mitochondria,
in cross-section.

14. Before combustion can occur, however, we have to get some “fuel” !

15. For that, we will need to break down glucose (or other sugars) OUTSIDE the mitochondria, in a process called

16. G L Y C O L Y S I S

17. G L Y C O L Y S I S:

18. G L Y C O L Y S I S:
is the breakdown of glucose (or
other sugars)

19. G L Y C O L Y S I S:
is the breakdown of glucose (or
other sugars)
requires an activation energy

20. G L Y C O L Y S I S:
is the breakdown of glucose (or
other sugars)
requires an activation energy
occurs in the cytoplasm

21. Polymers of glucose, like starch, are first broken into individual sugars through hydrolysis

22. The single sugars produced contain
stored energy in their chemical bonds, but they are still too big to pass through the mitochondrial membrane.

23. ATP provides the initial activation energy. The 6-carbon sugar will
be broken down in a series of steps
that do not involve oxygen.

24. C3H3O3
There will be a net gain of 2 ATP. The final products of glycolysis are two 3-carbon molecules of pyruvate (pyruvic acid)

25. C3H3O3
Pyruvate is small enough to be easily transported through the mitochondrial membrane, where a new series of chemical reactions take place. . .

26. The
Krebs
Cycle

27. The Krebs Cycle:
takes place in the matrix

28. The Krebs Cycle: C3H3O3 takes place in the matrix “acetyl CoA”
begins by converting each of the 3-carbon
pyruvates into a special complex called
acetyl CoA
. . Co-enzyme A is added
C3H3O3
“acetyl CoA”
Pyruvate enters
the matrix. . .
. . .a waste product ,
CO2 , is released . . .

29. The Krebs Cycle:
Acetyl CoA
begins the cycle
Acetyl CoA

30. As the cycle proceeds, CO2
The Krebs Cycle:
Acetyl CoA
begins the cycle
As the cycle proceeds, CO2
are removed
CO2
CO2

31. . . .an electron transport chain is charged!
The Krebs Cycle:
There is a net
gain in ATP,
and . . .
. . .an electron transport chain is charged! e-
CO2 e-
CO2
ATP

32. Electron Transport:
takes place in the cristae

33. Electron Transport:
takes place in the cristae

34. Electron Transport: Electron Transport: takes place in the cristae
will draw in H+, creating a high
concentration which can be used to
drive a proton pump

35. Proton Pumping:
powers the enzyme, ATP synthase

36. Proton Pumping: powers the enzyme, ATP synthase
…which is then used to make ATP

37. DOING THE MATH:
Glycolysis, in cytoplasm, no O2 4 ATP

38. DOING THE MATH: Glycolysis, in cytoplasm, no O2 4 ATP
Krebs Cycle, in matrix, no O2 2 ATP

39. DOING THE MATH: Glycolysis, in cytoplasm, no O2 4 ATP
Krebs Cycle, in matrix, no O2 2 ATP
Electron transport chains, with O2 32 ATP

40. DOING THE MATH: Glycolysis, in cytoplasm, no O2 4 ATP
Krebs Cycle, in matrix, no O2 2 ATP
Electron transport chains, with O2 32 ATP
TOTAL: ATP

41. DOING THE MATH: Glycolysis, in cytoplasm, no O2 4 ATP*
Krebs Cycle, in matrix, no O2 2 ATP
Electron transport chains, with O2 32 ATP
TOTAL: ATP
(-2 ATP)*
(*minus 2 ATP used for activation energy in glycolysis)

42. DOING THE MATH: Glycolysis, in cytoplasm, no O2 4 ATP*
Krebs Cycle, in matrix, no O2 2 ATP
Electron transport chains, with O2 32 ATP
TOTAL: ATP
(-2 ATP)*
NET YIELD, 1 glucose: net ATP
(*minus 2 ATP used for activation energy in glycolysis)