Light Reactions & Pigments pp. 116-124 PHOTOSYNTHESIS Part 2 Light Reactions & Pigments pp. 116-124

6CO2 + 6H2O  6O2 + C6H12O6 sunlight Questions to ask: Why is photosynthesis important? (provides oxygen for us, and food for plants to become food. Without plants, animals would die off. Without animals, humans would die off) What part of the plant “does” photosynthesis? ANS: Chloroplasts

Light and Pigments Chloroplasts contain pigments Pigments absorb specific colors of light Colors that are absorbed are NOT visible

Pigments Chlorophyll a: absorbs reds and blues Chlorophyll b: absorbs a lot of blue and some red Carotenoids: absorb blues and greens (colors seen in vegetables and during the fall season)

Light Absorption Clusters of pigments called photosystems absorb light energy Photosystems are located in the thylakoid membrane

Electron Transport Chain H2O is split by an enzyme Makes H+ (Protons) and O2 Also excites an electron that starts the electron transport chain

Electron Transport Chain Electrons (e-) from photosystems move down ETC and attach H+ to NADP+ to make NADPH This NADPH is used later on!

Chemiosmosis Makes ATP H+ moves through ATP synthase to make ATP ATP is used later on too!

Photosynthesis - Two Parts LIGHT REACTIONS: Make ATP, NADPH, and O2 CALVIN CYCLE: Uses the ATP and NADPH to make carbohydrates 1. Light absorption (by plant pigments) 2. Electron transport chain (making NADPH) 3. Chemiosmosis (making ATP)

Draw and fill in this chart! The bottom half will be filled in tomorrow! REACTION LOCATION REACTANTS PRODUCTS LIGHT REACTIONS Thylakoid Sunlight H2O O2 ATP NADPH

Vocab to keep in mind: Pigments Photosystems Light Reactions Electron Transport Chain Chemiosmosis