12/1/14 Objective: Photosynthesis Do Now If you reversed the equation for photosynthesis, what would it look like?

What is photosynthesis? 6CO 2 + 6H 2 O + light > C 6 H 12 O 6 + 6O 2 What do you notice about this equation?

Where does photosynthesis occur? chloroplast: organelle where photosynthesis takes place chlorophyll: chemical compound that gives green color –stomata: pores found on surface of leaf that allows gas and liquid exchange –CO 2 enters; O 2 exits

Structures of the Chloroplast stroma: thick fluid in inner membrane thylakoids: many disk- shaped sacs grana:stacks of thylakoids

The electromagnetic spectrum is the entire range of electromagnetic energy, or radiation

The Nature of Sunlight Like other electromagnetic energy, light travels in waves Wavelength is the distance between crests of waves Wavelength determines the type of electromagnetic energy Visible light consists of wavelengths (including those that drive photosynthesis) that produce colors we can see

Pigments pigments: a substances color due to chemical compounds –Light can be absorbed, transmitted or reflected A chloroplast’s pigments absorb blue- violet and red-orange very well Does not absorb green –Reflected or transmitted

Paper Chromatography Used to observe pigments in a green leaf chlorophyll a: absorbs mainly blue-violet and red- orange and reflects mostly green –Major role in photosynthesis chlorophyll b: “helper” pigment absorbs mainly blue and orange and reflects yellow-green. - carotenoids: “helper”- absorbs mainly blue- green and reflects yellow-orange Ex. carotein

Directions Cut out the chloroplast and label the stroma, thylakoid, and granum. Then cut out the reactants and products and paste them either entering or leaving the chloroplast. Answer the following questions: 1.Write the reaction for photosynthesis. 2.What organisms undergo photosynthesis? 3.In what organelle does photosynthesis occur? 4.When do plants do photosynthesis? 5.Why might plants help regulate the global climate? 6.What would happen if a dust cloud blocked out the sun for 100 years?

Photosystems photosystems: clusters of chlorophyll and other molecules in the thylakoid –Each contain a few hundred pigment molecules –Acts like a solar panel

Light Fig H2OH2O Chloroplast Light Reactions NADP + P ADP i +

Light Fig H2OH2O Chloroplast Light Reactions NADP + P ADP i + ATP NADPH O2O2

Light Fig H2OH2O Chloroplast Light Reactions NADP + P ADP i + ATP NADPH O2O2 Calvin Cycle CO 2

Light Fig H2OH2O Chloroplast Light Reactions NADP + P ADP i + ATP NADPH O2O2 Calvin Cycle CO 2 [CH 2 O] (sugar)

The Light Reactions Require sunlight 1. Chlorophyll molecules(in thylakoid) capture light energy 2. Captured energy used to split water into oxygen and hydrogen 3. Water’s electrons and H + ions are used to make NADPH and ATP 5. Oxygen is a bi-product and released through stomata

The Calvin Cycle “Light- independent reactions” occur in the stroma Makes sugar from CO 2 and H + and electrons carried by NADPH ATP from light reactions provides energy to power the cycle.