1. Photosynthesis & Cellular Respiration
Cell Functions
Photosynthesis & Cellular Respiration

2. Autotrophs & Heterotrophs
Plants and some other types of organisms are able to use light energy from the sun to produce food
The sun is the ultimate source of energy on Earth
Autotroph?
Heterotroph?

3. Autotroph or Heterotroph?

4. Chemical Energy & ATP
One of the main compounds used by living things to store energy is ATP
What does ATP stand for?
Cells can store energy by adding a phosphate to ADP to make ATP

6. Releasing energy
The energy stored in ATP is released when ATP is converted back to ADP and a phosphate group
The characteristics of ATP make it an exceptionally useful molecule that is used by all types of cells in their basic energy source

7. ATP and Glucose
Even though ATP is efficient at transferring energy, it is not good for long term storage
Cells can regenerate ATP from ADP as needed by using the energy in carbohydrates like glucose

8. Think About it
Why do we need to eat? Think about ATP…

9. Investigating Photosynthesis
1643—Jan Van Helmont
After careful measurements of water intake and weight increase, he concluded that trees gain most of their mass from water
1771—Joseph Priestley
Using a bell jar, a candle, and a plant, Priestley found that the plant releases a substance that keeps the candle burning—a substance that we now know is oxygen

10. Investigating Photosynthesis
1779—Jan Ingenhousz
Ingenhousz found that aquatic plants produce oxygen bubbles in the light but not in the dark. He concluded that plants need sunlight to produce oxygen

11. Photosynthesis
Photosynthesis is the process by which plants take light energy and turn it into chemical energy
6H2O + 6CO2 C6H12O6 + 6O2
Light

12. Light & Pigment
In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule in chloroplasts
Sunlight (“white” light) is actually a mixture of different wavelengths of light—visible color spectrum

13. Inside a Chloroplast Photosynthesis takes place inside the chloroplast
Chloroplasts contain pancake-like structures called thylakoids
Thylakoids contain chlorophyll and other pigments known as photosystems that are able to capture light energy

14. Chloroplast

15. Chloropyll
Plants absorb the sun’s light energy with light- absorbing molecules called pigments
The main pigment in plants is called chlorophyll
There are two kinds of chlorophyll, a and b

16. Photosynthesis Photosynthesis can be broken down into 2 parts:
Light Dependent Reaction
Takes place in the thylakoid
Calvin Cycle (light independent reaction)
Takes place in the stroma

17. Light dependent Reactions
Photosystem II
Electron Transport Chain
Photosystem I
ATP Formation

18. Photosystem II
Light is absorbed by chlorophyll or other pigments in photosystem II
The energy from the light is transferred to electrons, which are then passed on the electron transport chain. Separately, enzymes break up water molecules into electrons, hydrogen (H+), and oxygen