1. Photosynthesis

2. Photosynthesis
What? Who?
Why? How?
Where? When?

3. What is Photosynthesis?
Process by which light energy is converted to chemical energy in organic compounds.
Carbon Dioxide + Water + Light energy ----> glucose + Oxygen
6CO2 + 6H2O + light energy ---> C6H12O6 + 6O2

4. Why is photosynthesis important?
Beginning of food chain on land and shallow water
Why not in deep water?
Carbon Dioxide Reduction
Greenhouse gas that leads to global
warming!
Oxygen Production
What we breathe!

5. Where does photosynthesis occur?
Where chlorophyll is present
Cytoplasm of prokaryotes (bacteria)
Chloroplasts of eukaryotes (all other cells)

6. What is chlorophyll?
Chlorophyll is a pigment that has the ability to absorb certain visible wavelengths (red, blue,violet)
It reflects other wavelengths
Which?

7. Who can photosynthesize?
Autotrophs (organisms that can make organic compounds from inorganic compounds and energy from sunlight)
In the oceans (70%) by Cyanobacteria, algae,
On land by plants (moss, ferns, flowering plants, pines etc)

8. Are these Plants?
Pitcher Plants
Venus’s Fly Trap?

9. Atlantic Ocean
Winter
Spring
Fig. 6-1b, p.92

10. Chloroplast Granum – stack of thylakoids Outer membrane Inner membrane
Stroma – space inside
Thylakoid flattened disc shaped structures, contains chlorophyll
Granum – stack of thylakoids
Outer membrane
Inner membrane

11. Chloroplast Structure
central vacuole
chloroplast
Fig. 6-7b, p.96

13. Is white light really white?
shortest wavelengths
(most energetic)
range of most radiation
reaching Earth’s surface
range of heat escaping
from Earth’s surface
longest wavelengths
(lowest energy)
gamma rays x
rays
ultraviolet
radiation
near-infrared
radiation
infrared
radiation
microwaves
radio
waves
VISIBLE LIGHT
Wavelengths of light (nanometers)
Why are leaves green?

14. Algae Bacteria A crystal prism breaks up a beam of light into
a spectrum of colors, which are cast across a
droplet of water on a microscope slide.
part of an algal strand
stretched out across
a microscope slide
The Algae photosynthesized at the wavelenghts shown. Aerobic nonphotosynthetic bacteria gathered in the areas that had high oxygen (where photosynthesis was happening)
Algae
Bacteria
Fig. 6-6, p.95

15. Chlorophyll a
beta-carotene
Chlorophyll b
Fig. 6-4, p.95

16. Chloroplasts Contain Two Pigments
1. chlorophyll
the primary pigment involved in photosynthesis – most light absorbtion
absorbs mostly reds and blues – reflects greens and yellows
2. carotenoids
pigment that absorbs different wavelengths than chlorophyll – reflects mostly reds, oranges and yellows
responsible for autumn leaf colors

17. light harvesting complex electron transfer chain
PHOTOSYSTEM II
PHOTOSYSTEM I
thylakoid
membrane
thylakoid
compartment
Fig. 6-7d, p.97

18. Light Reaction/Photolysis
Chlorophyll in thylakoids absorbs light energy
Splits water molecule (lysis)
2H2O -> 4H+ + O2
Oxygen is released as byproduct
H+ ions accumulate in the thylakoid and the energy is used to make ATP
(ADP + P > ATP)
H+ and e + NADP > NADPH transported to stroma to make sugars

19. What Happens in the Light Reaction?
p.93b

20. What is ATP?
The fuel for cells. It allows cells to perform all the work necessary for survival, growth and reproduction.
How is ATP made?______
How do we make ATP? _____

21. Adenine P P P
CH2
3 phosphate groups
Ribose sugar

22. ATP ADP + P Energy from sun Energy released for work
Sum of all reactions in a cell > Metabolism
ATP
Energy from sun
Energy released for work
ADP + P
What kind of work does a cell perform?

23. 1 molecule of glucose gives you 32-38 ATP molecules!
Some ATP Facts:
Each cell on your body needs 1 billion ATP molecules every minute …. ATP cannot be stored or transported from a leaf cell
Has to be converted to sugars
1 molecule of glucose gives you ATP molecules!

24. Light Independent/Dark Reaction Calvin Cycle/Carbon fixation Reaction
Conversion of ATP and NADPH to sugars
Occurs in the stroma
Does not need light
Needs the products of the light reaction
Needs CO2 from atmosphere
Called cycle because some of the products are regenerated or cycled through the system

25. p.93c

26. Products of Calvin Cycle
Glucose - what happens to it?
NADP - what happens to it?
ADP + P -what happens to it?

27. So how do we humans get our energy?
From the food we eat - our life depends on autotrophs!
We are the
Along with other bacteria, fungi, and animals.
HETEROTROPHS

28. So what are chemoautotrophs
So what are chemoautotrophs? There are other kinds of autotrophs who can make their food, do not use the energy from SUN but from chemicals. Ex. Sulfur in deep sea hydrothermal vents.

29. What Else do we get from Photosynthesis?
1. Food (of course)
2. Clothing
3. Building material
4. Petroleum products