photosynthesis complete presentation

1. Photosynthesis
Chapter 8

2. Energy and Life
Section 8-1

3. Energy and Life
• Energy is the ability to do work.
• All living things use energy stored in
chemical compounds to survive. (FOOD)
• Heterotrophs – eat food to get energy
• Autotrophs – make their own food from
sunlight and inorganic molecules to get
energy.
• When are you not using energy?

4. Chemical Energy and ATP
• Energy from food is changed into another form
cells can use.
• Adenosine Triphosphate (ATP) – energy
molecule of the cell (made by what organelle?)
• Must break down the foods to generate the ATP.
• Breaking the bonds between the phosphate
atoms will release the energy from ATP.
• Used ATP is now ADP. (what is ADP?)
• Energy stored in foods (glucose) will change
ADP back into ATP.

5. Adenine Ribose 3 Phosphate groups
Section 8-1
ATP
The ATP molecule!
(Know this structure)

6. ADP ATP
Energy
Energy
Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)
Partially
charged
battery
Fully
charged
battery
Section 8-1
Figure 8-3 Comparison of ADP and
ATP to a Battery
ATP being made from ADP!
This energy that will be stored into the
ATP molecule which comes from food!

8. Photosynthesis: An Overview
Section 8-2

9. Who Were the Scientists?
◼ Jan Van Helmont – 1643
1. What do plants take from the soil?
2. Trees gain mass from water not soil.
◼ Joseph Priestley – 1771
1. Something in the air kept candle burning.
2. Plants released oxygen.
◼ Jan Ingenhouz – 1779
1. Oxygen was only produced by plants in
the presence of light.

10. Photosynthesis Equation
• 6CO2 + 6H2O -------→ C6 H12O6 + 6O2
Carbon dioxide + water ------→ sugar + oxygen
• Photosynthesis uses the sunlight to
convert water and carbon dioxide into
oxygen and high-energy sugars (glucose)!
• What will the plant do with the sugar it has
made?
• Generate ATP for cellular processes!
Light
Light

11. Light and Pigments
• Photosynthesis uses pigments in the leaf to
obtain sunlight.
• Pigments absorb and reflect light.
• Chlorophyll is the green pigment in
chloroplasts. Why is it green?
• Two main types of chlorophyll:
Chlorophyll a and Chlorophyll b
Other pigments (red, orange, yellow) are found in
Plastids which will absorb energy and transfer to
chlorophyll.

12. Absorption of Light by
Chlorophyll a and Chlorophyll b
V B G Y O R
Chlorophyll b
Chlorophyll a
Section 8-2
Figure 8-5 Chlorophyll Light Absorption
What wavelengths
does chlorophyll
work the best in?
What wavelengths
does chlorophyll
not work well in?
Which color light
would a plant grow
best under: Green,
red, yellow?

13. Section 8-2
Photosynthesis: Reactants and Products

14. The Reactions of
Photosynthesis
Section 8-3

15. The Chloroplast
Structure of Chloroplast:
1. Thylakoids – saclike photosynthetic
membrane (they look like pancakes!)
a. Contains light absorbing pigments
b. Light Dependent reaction occurs here
2. Grana(um) – stacks of thylakoids
3. Stroma – space surrounding the thylakoids
a. Calvin cycle occurs here.

17. The Reactions
Two reactions run the photosynthesis process:
1. Light-Dependent reaction
- sunlight required to run; it is a
reactant
2. Calvin Cycle (aka Light-Independent reaction)
- no sunlight required to run
- however, needs products of light
reaction to run.

18. Light Dependent Reaction
• Takes place in the thylakoids
• Sunlight excites electrons in chlorophyll
• Electron energy passed to carrier
molecule NADP+ to make NADPH.
• H2O is broken down to use H+ ions to
convert ADP to ATP by ATP synthase
protein.
• Oxygen atoms released as waste.

19. H2O
O2
Sugars
CO2
Light-
Dependent
Reactions
Calvin
Cycle
NADPH
ATP
ADP + P
NADP+
Section 8-3
Figure 8-7 Photosynthesis: An Overview

20. Light Independent Reaction or
Calvin Cycle
• Takes place in the stroma.
• CO2 combines a 5 carbon sugar to
produce two 3-carbon molecules.
• Catalyzed by the enzyme RUBISCO.
• ATP and NADPH from light phase convert
the 3-carbon molecules into glucose!

21. H2O
O2
Sugars
CO2
Light-
Dependent
Reactions
Calvin
Cycle
NADPH
ATP
ADP + P
NADP+
Section 8-3
Figure 8-7 Photosynthesis: An Overview

22. How is the Rate of
Photosynthesis Controlled?
• Availability of water – lack of water slows
process down – plants in warm climates
have waxy coating to reduce water loss
• Temperature – best rate occurs between
0 and 35 degrees Celsius
• Intensity of light – increasing light
intensity increases rate