Importance, Basics, & Details Photosynthesis Importance, Basics, & Details

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.

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

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

Details: How does photosynthesis occur? Two Steps Light dependent reactions (thylakoid membrane) 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!

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

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