1. Photosynthesis, Cellular Respiration
Biology 20
Photosynthesis,
Cellular Respiration

2. ATP WHAT IS ATP? Universal Energy Molecule
Energy in a form the cell can use
Makes energy readily available
Continuously being remade
Stands for Adenosine Triphosphate
P P P
Adenosine

3. ATP WHAT IS ATP? High Energy Bond Universal Energy Molecule
Makes energy readily available
Continuously being remade
Stands for Adenosine Triphosphate
P P P
P P P
Adenosine
Adenosine
High Energy Bond

4. ATP What is ATP used for? 1.Motion 2. Transport of ions and molecules.
3. Building molecules
4. Switching reactions on or off

5. Electron Transfer
The transfer of electrons is important in ATP production.
Electron carriers
strip a hydrogen proton and its electron from a number of organic compounds
Respiration
NAD (becomes NADH)
Photosynthesis
NADP+ (becomes NADPH)

6. Biology 20
Photosynthesis

7. Introduction Solar Energy Chemical Bond Converted Energy of
Photosynthesis is…
the process by which plants and some bacteria use chlorophyll, a green pigment, to trap sunlight energy.
The energy is used to synthesize carbohydrates
Solar
Energy
Chemical Bond
Energy of
Carbohydrates
Converted

8. Chlorophyll A green chemical which traps sunlight energy
Located in the chloroplast

9. Chloroplast Parts Thylakoid Stroma Disk Granum = stack of disks
Grana = many stacks
site of light dependent reaction
Stroma
gel surrounding the thylakoids
site of light independent reaction

10. Plant Cell
Chloroplast
Thylakoid Stacks
Thylakoid
Thylakoid Location

11. Leaves in the fall
Why do leaves change colors in the fall?

12. Pigments White light is composed of all colors Chlorophyll
red, orange, yellow, green, blue, indigo, violet
Chlorophyll
reflects green light
absorbs blue and red ends of the spectrum
chlorophyll a -- blue green
chlorophyll b -- green
Other pigments absorb light energy from other parts of the spectrum.
Carotenoids (orange)
Xanthophyll (yellow)

13. Leaves in the fall Because of light.
A decrease in light intensity and length.
Causes the chlorophyll molecule to break down, exposing the other pigments

14. General Equation C H O + 6O 6 CO + 6 H O2 2 2 6 12 6
There are two steps in photosynthesis
Light Dependent Reaction
Light Independent Reaction (no light required)

15. General Outline Water Light Energy ATP NADPH Sugar Oxygen
Carbon Dioxide
Light
Dependent
Reaction
Light
Independent
Reaction
ATP
NADPH
Sugar
Oxygen

17. Cellular Respiration
Explain how glucose is oxidized during Glycolysis and the Krebs Cycle to produce reducing power in NADH and FADH
Describe where in the cell this takes place
Explain how chemiosmosis converts the reducing power of NADH and FADH to store chemical potential energy as ATP
Describe where in the mitochondrion this takes place

18. Cellular Respiration Photosynthesis – stores energy
Cell Respiration – releases energy =
Sunlight Energy
H2O
Glucose
CO2 O2
Photosynthesis

19. Cellular Respiration Photosynthesis – stores energy
Cell Respiration – releases energy 
Sunlight Energy
H2O
Glucose
CO2 O2
Photosynthesis
Chemical Energy
+ 6 +
Glucose O2  6
+ 6
CO2
H2O
Cellular Respiration!

20. Notice that the wastes from photosynthesis are used as raw materials in cellular respiration
Atmospheric CO2 and water are used in photosynthesis, while Oxygen is released.
Atmospheric oxygen is used during Cellular respiration, while CO2 and water is released.

21. General Information
Cellular respiration the process by which cells break down glucose into carbon dioxide and water, releasing energy
You can think of respiration as the combustion of gasses in a car’s engine.

22. Car’s Engine
MAIN ENGINE = Mitochondrion – The site of the majority of ATP synthesis
MAIN FUEL = Glucose – fats and proteins may also be used in some instances
MAIN EXHAUST = CO2 and H2O.

23. The 4 Steps of Cellular Respiration
Glycolysis
Pyruvate Oxidation
3. Krebs Cycle
4. Electron Transport Chain

24. 1. Glycolysis (in cytoplasm)
Glucose
2 ATP
2 ADP
2 ADP
2 ADP
2 ATP
2 ATP +
NAD +
NAD
NADH
NADH
Pyruvic Acid
Pyruvic Acid

25. Mitochondria
mitochondrial matrix the fluid that fills the interior space of the mitochondrion

26. 2. Pyruvate Oxidation
After glycolysis, if there is oxygen available, the pyruvate molecules are changed so the Krebs cycle can use them.
CO2 portion is removed and released as waste product
An electron is released to NAD+  NADH
Pyruvate Acetyl-CoA

27. 3. Krebs Cycle Discovered by Sir Hans Kreb in 1937
The Krebs cycle is an eight-step process
Key features of the Krebs Cycle
During one complete cycle a total of three NAD+ and one FAD are reduced to form three NADH and one FADH
During one complete cycle one ATP is formed
During one complete cycle three CO2 molecules are produced
However since glycolysis provides 2 pyruvate molecules, we double all our numbers!

28. Krebs Cycle 2 ADP 2P 2 ATP 2 Acetyl CoA 4 Carbon Dioxide 6 NADH 6 NAD
2 FADH
2 FAD

30. 4. Electron Transport Chain
Occurs on the inner membrane of the mitochondrion
Involves a group of molecules built into the inner membrane of the mitochondrion
Electrons pulled off of food by Glycolysis and Krebs are passed between these molecules.
This will ultimately result in the production of ATP
Oxygen is required for this step.
Lots of ATP is made (32)

31. Mitochondria

32. Electron Transport Chain
Intermembrane
Space
Inner
Membrane
Matrix

33. High Energy
Electron + H
Intermembrane
Space + H
Electron H H
Membrane
Inner
Cytochromes H H
Low Energy
Electron
Matrix
NADH

34. So Where
Did All The
Energy Go??

35. + H
Intermembrane
Space + + + + H H H H + + + H H H + +
Membrane
Inner + H H H + + + H H H + H + + + H H H + + + H H H
Matrix
ADP
ATP P + + H + + + H H H H

36. + H
Intermembrane
Space + + + + H H H H + + + H H H + +
Membrane
Inner + H H H + + + H H H + H
Oxygen + + + H H H + + + H H H
Matrix
ADP
ATP P H O 2 + + H + + + H H H H

37. For each NADH that enters the Electron Transport Chain, how many ATP are produced?

38. For Each NADH Entering the ETC, 3 ATP Are Produced!
But What About FADH?

39. Each FADH is only
able to produce
2 ATP in the
ETC

40. chemiosmosis a process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme

43. What’s Up With Oxygen? Oxygen is the final electron acceptor.
If there is no oxygen, the electron transport chain gets “backed up” as there is no where for the electrons to go.
NADH NAD+
As a result, Krebs stops due to lack of NAD+
Lack of NAD+ also causes [H+] to increase
The body’s pH begins to fall inhibiting normal enzyme activity.

44. Review
Explain how glucose is oxidized during Glycolysis and the Krebs Cycle to produce reducing power in NADH and FADH
Describe where in the cell this takes place
Explain how chemiosmosis converts the reducing power of NADH and FADH to store chemical potential energy as ATP
Describe where in the mitochondrion this takes place

45. Let’s revisit Glycolysis!
Glycolysis created two molecules of pyruvate
Oxygen available  aerobic respiration occurs (Krebs, ETC)
No oxygen  anaerobic respiration

46. Anaerobic Respiration
Since pyruvic acid is poisonous, it must be converted into a safer form.
In animals (muscles!) -- LACTIC ACID
causes muscle cramps
process is called Lactic Acid Fermentation

47. Anaerobic Respiration
In bacteria and yeast -- ETHYL ALCOHOL & CO2
process is called Alcohol Fermentation
Both only Yield 2 ATP! Very inefficient!

48. Comparison of Photosynthesis and Respiration
Energy required
Oxygen released
CO2 and H20 required
Glucose produced
Respiration
Energy Produced
Oxygen required
CO2 and H20 produced
Glucose required