1. Importance, Basics, & Details
Photosynthesis
Importance, Basics, & Details

2. Importance of Photosynthesis?
Main energy input for almost all living organisms!
Solar Energy (light)  Chemical Energy (Carbs)
Food!
Responsible for much of the oxygen (O2) in the atmosphere!
Most living organisms, not all, require oxygen to live!
Understand why in next section…cellular respiration.

3. Basics: Where does photosynthesis occur?
Organisms
Plants, Algae, & Bacteria
Animals  Green sea slug?
Cells
Chloroplasts (2 membranes)
Thylakoids & Stroma

4. Basics: How does photosynthesis occur?
Two Steps:
Light Dependent Reactions
Light energy is absorbed by pigments in chloroplasts to make glucose sugars (carbs).
Water is broken down and an oxygen (O2) is released into the atmosphere
Calvin Cycle
Carbon dioxide (CO2) is used to provide the carbon atoms for the carbohydrate sugar (glucose)

5. Details: How does photosynthesis occur?
Two Steps
Light dependent reactions (thylakoid)
Uses energy from light to make ATP & NADPH
Light energy is also used to split water (making O2)
photolysis
Calvin Cycle reactions (stroma)
Carbon dioxide (CO2) is used to make glucose (C6H12O6)
An enzyme called rubisco adds CO2 into the reaction cycle
ATP and NADPH provide the energy for the cycle of reactions
Does NOT depend on light!

6. Photosynthesis Review
Almost all food and most of the oxygen we breathe comes from photosynthesis!
Plants, algae, and even bacteria can make their own food by photosynthesis!
Photosynthesis occurs in the chloroplasts of cells.
Thylakoid (“pancake” structures) and Stroma (liquid portion)
Light energy is transformed into chemical energy (carbs)
Light reactions occur in the thylakoids
ATP and NADPH are made here
Water is split, and oxygen is given off
The Calvin Cycle occurs in the stroma
Energy from ATP and NADPH is used to transform carbon dioxide and other carbon compounds into carbohydrates

7. What’s Next? Quick lab on page 205 Photosynthesis Quiz
Have 3 attempts to get above 75%
Will take average of all tests (up to 75%)
Quick lab on page 205
Turn into box when complete