13 1 Ecologists Study Relationships 13 1 Ecologists

13. 1 Ecologists Study Relationships

13. 1 Ecologists Study Relationships PHOTOSYNTHESIS

4. 2 Overview of Photosynthesis KEY CONCEPT Photosynthesis is a series of chemical reactions that transform light energy into chemical energy stored in food.

4. 2 Overview of Photosynthesis Chemical Equation of Photosynthesis 6 CO 2 + 6 H 2 O Carbon dioxide + Water REACTANTS Carbon dioxide Water Sunlight Energy C 6 H 12 O 6 + 6 O 2 Glucose + Oxygen PRODUCTS Glucose (sugar) Oxygen

4. 2 Overview of Photosynthesis • CO 2 enters a leaf through guard cell/stomata by diffusion

4. 2 Overview of Photosynthesis • H 2 O enters roots through osmosis.

4. 2 Overview of Photosynthesis Chloroplasts • In plants, Photosynthesis occurs in chloroplasts

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

. 4. 2 Overview of Photosynthesis Chloroplast vs. Chlorophyll chloroplast • Chloroplast = Organelle where photosynthesis occurs leaf cell • Chlorophyll = Green colored molecule that “fills” the chloroplast leaf

4. 2 Overview of Photosynthesis 2 Stages of Photosynthesis Reactions 1. Light Dependent Reactions *Require light energy 2. Light Independent Reactions *Do NOT require light energy

4. 2 Overview of Photosynthesis Light-Dependent Reactions . Requires Light energy and Water as reactants *Occur in the thylakoid *Produces high energy molecules that will transfer their energy to the Light Independent Rxns. *Waste product is Oxygen

4. 2 Overview of Photosynthesis Stage 1: LIGHT DEPENDENT REACTIONS

4. 2 Overview of Photosynthesis Steps of the Light Dependent Reactions 1. Light energy “excites” electrons in a chlorophyll molecule. 2. The “excited”, high energy electrons are passed from one protein molecule to another along the electron transport chain in the thylakoid membrane and are used to make 2 energy carrier molecules 3. Enzymes split the water molecule: H 2 O 2 H+ + 2 e- + O* The 2 e- replace the electrons the chlorophyll molecule lost * Oxygen gas is released

4. 2 Overview of Photosynthesis • Light-Independent Reactions (Calvin Cycle) • Do NOT require light energy – can happen in the dark • Source of Energy: the energy stored in high E molecules made in the light rxns • Occurs in the stroma fluid

4. 2 Overview of Photosynthesis *CO 2 is needed – it diffuses across the chloroplast membrane into the stroma. *CO 2 is rearranged using H+ from the breakdown of water and Energy from energy carrying molecules made in the light dependent reactions to make GLUCOSE.

4. 2 Overview of Photosynthesis Making the Energy Storing GLUCOSE Is the #1 Job of PHOTOSYNTHESIS

4. 2 Overview of Photosynthesis Big Picture of Energy Transformation in Photosynthesis • Light Dependent Reactions – • Chlorophyll molecule captures and transforms Light Energy into Chemical energy temporarily stored in energy carrier molecules. • Light Independent Reactions – • Chemical E from the energy carrier molecules made in Light Dependent reactions is transformed and stored as chemical energy in glucose

4. 2 Overview of Photosynthesis plays a role in carbon cycling • Inorganic Carbon in CO 2 gas from the atmosphere gets “fixed” into organic compounds like carbohydrates, lipids and proteins.

4. 2 Overview of Photosynthesis The Big Picture • Write the chemical equation for Photosynthesis using logic or memory – No Notes Allowed!!

4. 2 Overview of Photosynthesis The Big Picture Write the chemical equation for Photosynthesis using logic or memory – No Notes Allowed!! 6 CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2

4. 2 Overview of Photosynthesis Sample Exam Question • Using a microscope, a student observes a small, green organelle in a plant cell. • What is the name of this organelle? • Which energy transformation occurs first within the organelle? A. ATP to light B. Light to Chemical C. Heat to Electrical D. Chemical to Chemical

4. 2 Overview of Photosynthesis Sample Exam Question • Using a microscope, a student observes a small, green organelle in a plant cell. • What is the name of this organelle? Chloroplast • Which energy transformation occurs first within the organelle? A. ATP to light B. Light to Chemical C. Heat to Electrical D. Chemical to Chemical

4. 2 Overview of Photosynthesis • Photosynthesis is series of chemical reactions that involve the transformation of energy from one form to another. The many reactions of photosynthesis are grouped into two set of reactions. Name each reaction set. Explain the energy transformation that occurs in each.

4. 2 Overview of Photosynthesis • Photosynthesis is series of chemical reactions that involve the transformation of energy from one form to another. The many reactions of photosynthesis are grouped into two set of reactions. Name each reaction set. Explain the energy transformation that occurs in each. • Light Dependent Rxns Light Energy. > Chemical E stored in energy carrying molecules • Light Dependent Rxns Chemical E in energy carriers > Chemical E stored in glucose

4. 2 Overview of Photosynthesis • Overall Energy Transformation in Photosynthesis • Light Energy > Chemical Energy stored in Glucose

4. 2 Overview of Photosynthesis Sample Exam Question • Photosynthesis and cellular respiration are two major processes in which carbon atoms are cycled through the bodies of living things.

4. 2 Overview of Photosynthesis • The equation for the overall process is: 6 CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2 granum (stack of thylakoids) 1 chloroplast su nli gh t 6 H 2 O thylakoid 6 CO 2 3 6 O 2 2 energy stroma (fluid outside thylakoids) 1 six-carbon sugar 4 C 6 H 12 O 6

4. 2 Overview of Photosynthesis Water is absorbed by osmosis through the roots

4. 2 Overview of Photosynthesis