1. Photosynthesis

2. Autotroph vs. Heterotroph
Autotroph- organism that makes its own food
We call autotrophs Producers
Plants, algae
Heterotroph- an organism that cannot make its own food
Obtain energy by eating other organisms
We call heterotrophs Consumers
Animals, most bacteria, fungi

3. THE BASICS OF PHOTOSYNTHESIS
Almost all plants are photosynthetic autotrophs, as are some bacteria and protists
Autotrophs generate their own organic matter through photosynthesis
Sunlight energy is transformed to energy stored in the form of chemical bonds
(c) Euglena
(d) Cyanobacteria
(b) Kelp
(a) Mosses, ferns, and
flowering plants

4. Photosynthesis
Photosynthesis occurs in all cells with chloroplasts (mainly plants)
Step 1: photo-
Light energy is harvested
Step 2: -synthesis
Sugar is made

5. 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
Carbon dioxide
Water
Glucose
Oxygen gas
PHOTOSYNTHESIS
Glucose = sugar or carbohydrate

6. What’s with Light???

7. THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH

8. Electromagnetic Spectrum and Visible Light
Gamma rays
Infrared & Microwaves
X-rays UV
Radio waves
Visible light
Wavelength (nm)

9. WHY ARE PLANTS GREEN?
Different wavelengths of visible light are seen by the human eye as different colors.
Gamma rays
Micro- waves
Radio
waves
X-rays UV
Infrared
Visible light
Wavelength (nm)

10. Why are plants green?
Reflected light
Transmitted light

11. The feathers of male cardinals are loaded with carotenoid pigments
The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others.
Reflected light
Sunlight minus absorbed wavelengths or colors equals the apparent color of an object.

12. THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED
Chloroplasts absorb light energy and convert it to chemical energy
Reflected
light
Light
Absorbed
light
Transmitted
light
Chloroplast

13. Where does photosynthesis take place?
Question:
Where does photosynthesis take place? 13

14. In the chloroplasts!! Chloroplast LEAF CROSS SECTION MESOPHYLL CELL
Intermembrane space
Outer
membrane
Granum
Inner membrane
Grana
Stroma
Thylakoid compartment
Stroma
Thylakoid

15. Chloroplasts are comprised of:
outer membrane and inner membrane (together form the chloroplast envelope)
stroma (a thick fluid)
thylakoids (called grana when in stacks)
The pigement chlorophyll is imbedded in the thylakoid memebrane
Notice that the Thylakoid stacks are connected together

16. Where Photosynthesis happens
Pigment molecules called chlorophyll are on the surface of the thylakoid membrane
Chlorophyll gives plants their green color
Chlorophyll molecules absorb and capture light energy from the sun
The chlorophyll then uses the energy to combine H, C, and O atoms into sugars and oxygen molecules
Nearly all of the Oxygen in our atmosphere has been produced by plants

17. In Summary… Photosynthesis
Chloroplasts convert light energy into chemical energy
Carbon
Dioxide
+ Water + Light
 Sugar + Oxygen
6 CO2 + 6 H2O + light energy  C 6H12O6 + 6 O2

18. pigments in the chloroplast- not just chlorophyll
Chlorophyll a: most common pigment in chloroplast (absorbs blue &red light and reflects green light thus giving the chloroplast a green color)(chloro = green phylla + leaf)
Accessory pigments: additional pigments that absorb different wavelengths (carotene, chlorophyll b, & xanthophyll)

20. But it’s not that easy… Photosynthesis occurs in two different phases
Figure 4.29 The Calvin cycle.
Carbon dioxide enters the Calvin cycle. The energy of ATP is used to add hydrogens and electrons from NADPH to produce sugars.

21. The Light Phase This phase occurs in the thylakoid
In this phase, light is captured by the chlorophyll molecules
The chlorophyll molecules use the energy from the light to make:
ATP (cellular energy molecule)
NADPH (another high energy molecule)
Both of these molecules move on to the dark phase

22. “Waste” Products
Water is split, and Oxygen created during the light phase
Oxygen is released, hydrogen molecules from the water used in dark phase
Remember, this is the Oxygen that you breathe

23. The complicated view… (not on test)
Figure 4.28 The light reactions.
During the light reactions of photosynthesis, light strikes chlorophyll molecules located in the thylakoid membrane, exciting electrons that then move to a higher energy level. The energy of the excited electrons is harvested in a stepwise manner as the electrons are handed down an electron transport chain, producing ATP and NADPH that will be used by the Calvin cycle. A look at the events occurring on the thylakoid membrane: (1) A proton gradient is generated inside the thylakoid; and (2) both ATP and NADPH are synthesized in the stroma, where they will be available to the enzymes of the Calvin cycle.

24. The simplified version (on test)
1. light
2. H2O
3. CO2
5. granum
6. light reaction
11. Calvin
Cycle
7. NADP+
8.ADP+P_
9.ATP
10.NADPH
13. O2
14. sugar
4. stroma
12. thylakoid
Light Reactions

25. The Calvin Cycle
Also known as the Light Independent or Carbon fixation phase
This set of reaction does not rely on light
Occurs in the stroma (fluid inside of chloroplast)

26. The calvin cycle uses the H from the H20 and the C from the CO2
It also utilizes the ATP and the NADPH from the Light Reactions
With these components, sugars are made in the stroma

27. 3. CO2 1. light 9.ATP 2. H2O 4. stroma 7. NADP+ Cycle 10.NADPH
5. granum
6. light reaction
11. Calvin
Cycle
7. NADP+
8.ADP+P_
9.ATP
10.NADPH
13. O2
14. sugar
4. stroma
12. thylakoid
Calvin Cycle

28. What is the Purpose? Sugar is produced during this phase
Sugar can be used to synthesize more complex molecules like:
Starch
Fats/Lipids
Sugar can be used to make ATP during cell Respiration
It can be stored in the tissues of organisms

29. So what does a plant need?
Bring In
light
CO2
H2O
Let Out O2
Produce
sugars
leaves
shoot
roots
6CO2
6H2O
C6H12O6
6O2
light
energy  +

30. Factors Affecting Rate of Photosynthesis
Temperature: increases rate up to a certain point
Light Intensity: increases rate up to a certain point
CO2 level: Increases rate up to a certain point
Water: decrease water, decrease photosynthesis
Minerals; Ex. Magnesium, Nitrogen

31. Photosynthesis Summary
Who?
Green plants, algae, autotrophs
Materials:
CO2 + Water + Light
Energy Source:
Light + Sunlight
Products:
Food + Oxygen
Timing:
When light is present
Location:
chloroplast