1. PHOTOSYNTHESIS

2. How do organisms get energy?
Autotrophs and Heterotrophs
Autotrophs – organisms that can capture energy from sunlight or chemicals and use it to produce its own food.

3. How do organisms get energy?
Autotrophs and Heterotrophs
Heterotrophs – organism that obtains energy from the foods it consumes

4. Chemical Energy and ATP
ATP (adenosine triphosphate) = The principal chemical compound that living things use to store energy
ATP = 3 Phosphate groups

5. ADP (adenosine diphosphate) has a very similar structure to ATP, but with only two phosphate groups.
ADP = 2 Phosphate groups

6. Chemical Energy and ATP
The energy stored in ATP is released when ATP is converted to ADP. The breaking of the bond between the second and third phosphate group releases this energy.

7. Chemical Energy and ATP
ADP
Fully charged battery
Partially charged battery

8. Investigating Photosynthesis
When a tiny seedling grown into a tall tree with a mass of several tons, where does the tree’s increase in mass come from? From soil? From water? From air?

9. Investigating Photosynthesis
Van Helmont – 1600s
Wanted to know if plants grew by taking material out of the soil.
Weighed a pot of dry soil and a small seedling. He watered it regularly and at the end of five years the seedling had gained 75 kg. The mass of the soil was exactly the same.
Helmont concluded that the mass gain came from water
HE WAS WRONG

10. Investigating Photosynthesis
Priestly – 1700s
Put a candle under a bell jar, the fire went out. Added a small plant and the fire continued to burn for a few days.

11. Through the work of all these scientists it was discovered that…..
In the presence of light, plants transform carbon dioxide and water into carbohydrates and release oxygen

12. Investigating Photosynthesis
Ingenhousz
Showed that Priestly’s results were only valid if the plant was exposed to light.

13. Photosynthesis 6CO2 + 12H2O + light → C6H12O6 + 6O2
Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into oxygen and high-energy sugars

14. Light and Pigments
Plants gather the sun’s energy with light-absorbing molecules called pigments.
The plant’s principal pigment is chlorophyll

15. Inside a Chloroplast Photosynthesis takes place inside the chloroplast
Chloroplasts contain saclike membranes called thylakoids (looks like a pancake)
A stack of thylakoids is known as grana (looks like a stack of pancakes)
The area outside of the grana, but inside the chloroplast is known as stroma (kind of like the syrup on the pancakes)

16. Inside a Chloroplast

17. The Chemical Reactions of Photosynthesis
NADPH
Like ATP, the molecule NADPH can also store energy.
NADP+ + Energy  NADPH
So when an organism breaks down NADPH energy it gets NADP+ and energy
NADPH
NADP+
Fully charged battery
Partially charged battery

18. The Chemical Reactions of Photosynthesis
Light-Dependent Reactions
REQUIRE LIGHT
Light-dependent reactions produce oxygen gas and convert ADP and NADP+ into the energy carriers ATP and NADPH
Harvests the sun’s energy and charges the battery

19. The Chemical Reactions of Photosynthesis
Calvin Cycle
Because the Calvin Cycle does not require light, it is also called light-independent reactions
The Calvin cycle uses ATP and NADPH form the light-dependent reactions to produce sugar
Uses the energy stored in the light-dependent reactions to create food.

20. Factors Affecting Photosynthesis
Weather
Amount of rain
Temperature
Intensity of light