8.2 & 3 The Process of Photosynthesis

Key Questions What happens during the Light Dependent Reactions? What happens during the Light Independent Reactions? What factors affect photosynthesis? What are electron carrier molecules? What are the reactants and products in photosynthesis?

Photosynthesis is a biochemical pathway Two parts 1.Light dependent reaction 2.Light independent reaction (Calvin Cycle)

3 Stages of Photosynthesis Stage 1: Energy is captured from sunlight Stage 2: Light energy is converted to chemical energy (ATP + NADPH) Stage 3: Energy is used to form glucose

High Energy Electrons Energy carriers— Oven Mitt/Bucket analogy NADP+ NADP+, 2e -, H +

Light Dependent Reaction Photosystem II p. 237 Thylakoids Chlorophyll--blue and red absorbed -green and yellow reflected Carotenoids -red and orange reflected Light splits water molecule into: 4H + + 4e - + O 2

Light Dependent Reaction Electron Transport chain Excited e - are passed along thylakoid membrane

Light Dependent Reaction Photosystem I Light Absorbed Again NADP + takes a H+ ion and 2 e - becomes NADPH Minimal amount of ATP made (to be used later) Diffuse H + into stroma

Light Independent Reaction Calvin Cycle p. 238 Stroma No light required ATP, NADPH come in from light reactions CO 2 comes in from the atmosphere ADP, NADP + and C 6 H 12 O 6 (Glucose) made

Rate of Photosynthesis Dependent on: Light intensity (most import) CO 2, H 2 O Temperature