1. PHOTOSYNTHESIS

3. REMEMBER THIS? C6H12O6 + 6O2  6CO2 + 6H2O + ATP
Where did this come from?

4. Let’s ‘rearrange’ that cellular respiration equation:
But wait! Where’s the energy?!
Here it is!

6. What part of the sun’s energy is useful for photosynthesis?

7. Plants are green. What wavelengths of light are reflected from their green chlorophyll molecules?

8. Now that you know a little about the properties of light, let’s take a little quiz: (no pencils required!)
What wavelengths of light are reflected from this sentence?
RED
What about this?
(BLUE)
And this?
(PURPLE)
A trick question: What about this sentence?
NO COLORS: ALL COLORS ARE ABSORBED
An even tricker question: What about this word
It’s WHITE, which is all colors of light

9. What organisms perform photosynthesis?
Plants
Photosynthetic bacteria (cyanobacteria)
Photosynthetic protists

10. We’ll focus on plants, because they are eukaryotes
In a plant, where does most photosynthesis take place?

11. We know that the organelle responsible for carrying out photosynthesis is the chloroplast.

12. Chloroplast structure:
How do photosynthetic prokaryotes carry out photosynthesis? They have no organelles!

13. Cyanobacteria
Endosymbiotic Theory?

14. Photosynthesis consists of two parts:
The light reactions, which take place in the
thylakoid membrane
And the Calvin Cycle, which takes place in the
stroma
Let’s look at an overview of the light reactions first.

15. Chlorophyll is a pigment, which means it is a molecule that reflects certain wavelenths of light
Some of its electrons can get ‘excited’ by blue and red wavelengths of light

16. These ‘excited’ electrons have been boosted to a higher energy level, farther away from the nucleus, by photons. When they fall back to their ground state, that extra energy is released and is available to do work.

17. The LIGHT Reactions!

18. Now we have some ATP and some NADPH…..what’s the point
Here’s the point!

19. The Calvin Cycle: Part one: CARBON FIXATION

20. The Calvin Cycle: Part two: REDUCTION

21. The Calvin Cycle: Part three:
REGENERATION OF RuBP

22. RUBISCO
The most
ABUNDANT protein
on EARTH

23. REVIEW!

24. When plants’ Calvin Cycle uses CO2 directly from the air = C3 plants
First compound made has 3 carbons
Many food crops (grains)
What if there is a drought? What happens to stomata when it is hot and dry?
How does this impact photosynthesis?

25. Plant adaptations for hot dry weather:
C4 plants:
In hot/dry conditions, these plants keep their stomata closed
CO2 first fixed in a 4 carbon compound
Transfers CO2 to bundle sheath cells where there is a high [CO2]
‘spatial separation’
Example: sugar cane

26. Plant adaptations for hot dry weather:
CAM Plants
these plants always keep their stomata closed during the day
First fix CO2 in a 4C molecule during the night
CO2 released from 4C compound during day
Temporal separation
Examples:
Pineapples
Most cacti

27. How does photosynthesis affect global warming?
Photosynthesis removes CO2 from the atmosphere and ‘stores’ it in ‘sinks’ such as forests