1. Chapter 8 Photosynthesis

2. 8-1 Energy and Life
8-1 Energy and Life

3. 8-1 Energy and Life
Autotrophs
Make their own food

4. 8-1 Energy and Life
Heterotrophs
Cannot make their own food

5. Chemical Energy and ATP
8-1 Energy and Life
Chemical Energy and ATP
The principal chemical compounds that cells use to store and release energy is called ATP adenosine triphosphate

6. Storing Energy ATP stores energy in the third phosphate
8-1 Energy and Life
Storing Energy
ATP stores energy in the third phosphate
ATP is like a fully charged battery

7. Releasing Energy Q: How is the energy in ATP released?
8-1 Energy and Life
Releasing Energy
Q: How is the energy in ATP released?
A: Break bond between the second and 3rd phosphates 2
ADP

8. 8-1 Energy and Life

9. Using Biomechanical Energy
8-1 Energy and Life
Using Biomechanical Energy
Active Transport
Movement of organelles through cell
Sythesis of proteins and nucleic acids
Produce light
Blink of firefly caused by an enzyme powered by ATP

10. 8-1 Energy and Life
ATP Availability
Most cells only have enough ATP for a few seconds of activity
Why?
Not good at storing energy over the long term
Glucose stores 90X the chemical energy of ATP
Cells generate ATP from ADP as needed by using the energy in foods like glucose

11. 8-2 Photosynthesis: an Overview

12. During Photosynthesis…
8-2 Photosynthesis an Overview
During Photosynthesis…
Organisms (plants) absorb light energy from the sun and store it in organic compounds.
Energy is crucial to all life, without it work could not be done.

13. AN OVERVIEW OF PHOTOSYNTHESIS
8-2 Photosynthesis an Overview
AN OVERVIEW OF PHOTOSYNTHESIS
Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water

14. An example of basic photosynthesis…
8-2 Photosynthesis an Overview
An example of basic photosynthesis…

15. The Photosynthesis Equation
8-2 Photosynthesis an Overview
The Photosynthesis Equation
light
CO2 +
H2O
C6H12O6 + O2
(Carbon Dioxide)
(Water)
(Sun)
(Glucose)
(Oxygen)

16. Because light is a form of energy…
8-2 Photosynthesis an Overview
Because light is a form of energy…
Anything that absorbs light also absorbs the energy from that light
When chlorophyll absorbs light, much of the energy is transferred to electrons in the chlorophyll molecule, raising the energy level of these electrons
These high-energy electrons make photosynthesis work

17. 8-2 Photosynthesis an Overview

18. Chloroplasts 8-2 Photosynthesis an Overview
The site of Light Dependent Reactions
These organelles are surrounded by a double membrane and contain an inner membrane separate into disk like sacs called thylakoids
Thylakoid are arranged into granum, or neat stacks
Each thylakoid contains the green pigment chlorophyll
The light absorbing pigments are organized into photosystems, which transfer energy during the light reactions

19. 8-2 Photosynthesis an Overview

20. Pigments in chloroplasts
8-2 Photosynthesis an Overview
Pigments in chloroplasts
Chloroplasts absorb all other color pigments, leaving green to be reflected resulting in a plant’s color.
Chlorophyll a and b are
two are the 2 most
common types of chlorophyll
Chlorophyll b absorbs colors or
light energy NOT absorbed by
chlorophyll a
Light
Reflected
light
Absorbed
Transmitted
Chloroplast

21. 8-2 Photosynthesis an Overview
Absorption of Light by
Chlorophyll a and Chlorophyll b
Absorption of Light by
Chlorophyll a and Chlorophyll b
Chlorophyll b
Chlorophyll a V B G Y O R

22. 8-3 The Reactions of Photosynthesis

23. 8-3 Reactions of Photosynthesis

24. Thylakoids Sac-like photosynthetic membranes arranged in stacks
8-3 Reactions of Photosynthesis
Thylakoids
Sac-like photosynthetic membranes arranged in stacks

25. 8-3 Reactions of Photosynthesis
Grana
Stacks of thylakoids

26. Stroma The region outside the thylakoid
8-3 Reactions of Photosynthesis
Stroma
The region outside the thylakoid

27. Scientists describe the reactions of photosynthesis in two parts
Light – dependent reactions (in the thylakoid membranes)
Light – independent reactions (takes place in stroma)

28. 8-3 Reactions of Photosynthesis

29. Photosynthesis Consists of 2 Stages
8-3 Reactions of Photosynthesis
Photosynthesis Consists of 2 Stages
Non-light dependent (dark) reactions
Takes place in the Stroma
Includes the Calvin cycle
Does not literally occur in the dark, but requires no light to occur
Carbon dioxide is split,
Carbon to make sugars
 ATP + NADPH2 + CO2  + C6H12O6
Light dependent reactions
Take place in the Thylakoid Membrane
Depends on sunlight for activation energy
Responsible for the absorbing of light in Photosynthesis
Water is split,
giving off oxygen
H2O  + O2 + ATP + NADPH2

30. 8-3 Reactions of Photosynthesis

31. 8-3 Reactions of Photosynthesis
Carrier Molecule
Compound that can accept a pair of high energy electrons and transfer them along with most of their energy to another molecule
Ex.) NADP+

32. 8-3 Reactions of Photosynthesis

33. Q: What does this do? A: this traps sunlight in chemical form
8-3 Reactions of Photosynthesis
Q: What does this do?
NADP + H NADPH
A: this traps sunlight in chemical form

34. Light Dependent Reactions
8-3 Reactions of Photosynthesis
Light Dependent Reactions
Uses energy from light to produce
Oxygen gas
ATP
NADPH

35. 8-3 Reactions of Photosynthesis
Watch The Light Reaction Video

36. 8-3 Reactions of Photosynthesis

37. 8-3 Reactions of Photosynthesis
Watch The Light Reaction Video

38. 8-3 Reactions of Photosynthesis
The Calvin Cycle
The ATP and NADPH formed by the light-dependent reactions contain an abundance of chemical energy, but they are not stable enough to store that energy for more than a few minutes.
The Calvin cycle uses ATP and NADPH from light – dependent reactions to produce high energy sugars

39. 8-3 Reactions of Photosynthesis
The Calvin Cycle
These reactions don’t require light, therefore these reactions are called
Light – independent reactions

40. 8-3 Reactions of Photosynthesis
Watch The Calvin Cycle Video

41. 8-3 Reactions of Photosynthesis
Watch The Calvin Cycle Video

42. Factors Affecting Photosynthesis
8-3 Reactions of Photosynthesis
Factors Affecting Photosynthesis
Not enough water
Temperature
Light intensity

43. Review: Photosynthesis uses light energy to make food molecules
8-3 Reactions of Photosynthesis
Review: Photosynthesis uses light energy to make food molecules
Chloroplast
Light
Stack of
thylakoids
ADP
+ P
NADP
Stroma
reactions
Calvin
cycle
Sugar used for
 Cellular respiration
 Cellulose
 Starch
 Other organic compounds

44. 8-3 Reactions of Photosynthesis