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13.1 Ecologists Study Relationships PHOTOSYNTHESIS.

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Presentation on theme: "13.1 Ecologists Study Relationships PHOTOSYNTHESIS."— Presentation transcript:

1 13.1 Ecologists Study Relationships PHOTOSYNTHESIS

2 4.2 Overview of Photosynthesis KEY CONCEPT Photosynthesis is a series of chemical reactions that transform light energy into chemical energy stored in food.

3 4.2 Overview of Photosynthesis Chemical Equation of Photosynthesis 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Carbon dioxide + Water Glucose + Oxygen REACTANTS PRODUCTS Carbon dioxide Glucose (sugar) Water Oxygen Sunlight Energy chlorophyll Sunlight Energy chlorophyll

4 4.2 Overview of Photosynthesis

5 CO 2 diffuses into leaf cells through stomata pores

6 4.2 Overview of Photosynthesis Water is absorbed by osmosis through the roots

7 4.2 Overview of Photosynthesis In plants, Photosynthesis occurs in chloroplasts. chloroplast leaf cell leaf Chloroplasts are green colored organelles that contain the green pigmented molecule chlorophyll Chloroplast = Organelle Chlorophyll= Molecule

8 4.2 Overview of Photosynthesis Structure of the Chloroplast Organelle 1.) Thylakoids- coin shaped compartments surrounded by a membrane 2.) Grana – Stacks of coin shaped thylakoids 3.) Chlorophyll – light absorbing green molecule in thylakoid membrane 4.) Stroma – Fluid filled space between grana chloroplast stroma grana (thylakoids)

9 4.2 Overview of Photosynthesis There are Two Main Stages of Photosynthesis 1. Light-Dependent Reactions – Require Light Energy 2. Light-Independent Reactions – Do Not Require Light Energy

10 4.2 Overview of Photosynthesis Light-Dependent Reactions - capture energy from sunlight. *Light energy is needed *Water is needed *Occur in the chlorophyll filled thylakoid membrane *Produce molecules that provide E to Light Independent Rxns. (ATP and NADPH – High Energy Molecules) *Waste byproduct is Oxygen

11 4.2 Overview of Photosynthesis Basic Steps of the Light Dependent Reactions 1. Light energy “excites” the electrons in the chlorophyll molecule. 2. “Excited”, high energy electrons are passed from one protein molecule to another along the electron transport chain in the thylakoid membrane and are picked up by two molecules: NADP to form NADPH High E molecules needed to ADP to form ATP power the Light Independent Rxns 3. Enzymes split the water molecule: H2O 2H+ + 2e- + O- * The 2e- replace the electrons the chlorophyll molecule lost * Oxygen gas is released

12 4.2 Overview of Photosynthesis Light-Independent Reactions (Calvin Cycle) Do NOT require light energy – can happen in the dark Requires ATP and NADPH as energy source Occurs in the stroma CO 2 needed. CO 2 enters through the leaf stomata by diffusion Glucose molecules made

13 4.2 Overview of Photosynthesis Basic Steps of the Light Independent Reactions (Calvin Cycle) 1. CO 2 molecules diffuse across the stroma. 2. CO 2 is rearranged using H+ and Energy from ATP and NADPH to make glucose. Carbon gets ”fixed” into organic compounds – Carbohydrates, Lipids, Proteins

14 4.2 Overview of Photosynthesis Light Dependent Reactions – Capture Light Energy Light Independent Reactions - Make Sugars

15 4.2 Overview of Photosynthesis The equation for the overall process is: 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 C 6 H 12 O 6 granum (stack of thylakoids) thylakoid sunlight 1 six-carbon sugar 6H 2 O 6CO 2 6O 2 chloroplast energy stroma (fluid outside the thylakoids)


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