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Photosynthesis

Photosynthesis. Objectives: Describe the structure of a chloroplast Explain who ATP releases energy Explain the steps to photosynthesis. Energy. Energy is stored in chemical bonds and released at a later date. Cellular energy is stored by ATP Adenosine Triphosphate

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Photosynthesis

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  1. Photosynthesis Objectives: Describe the structure of a chloroplast Explain who ATP releases energy Explain the steps to photosynthesis

  2. Energy • Energy is stored in chemical bonds and released at a later date. • Cellular energy is stored by ATP • Adenosine Triphosphate • Contains 2 high energy phosphate bonds • Also contains nitrogen base adenine and a ribose sugar

  3. ADP • Adenosine diphosphate • What is formed when ATP loses 1 phosphate • ATP releases energy and a free phosphate. This forms ADP • When ATP turns to ADP….energy is released • Energy is used to make ATP again

  4. Importance of ATP • Main compound used to store energy in living things • Provides all of the energy for cell activities • Adding a phosphate group to ADP stores energy • Removing a phosphate group from ATP releases energy and makes ADP

  5. Pigments and Chloroplasts • Chlorophyll—primary light-absorbing pigment in autotrophs • Found inside chloroplasts • Chlorophyll a • Found in all plants • Participates directly in light reactions • Chlorophyll b • Accessory pigment • Indirectly works in photosynthesis • Both a and b absorb red and blue light

  6. Structure of a Chloroplast

  7. Structure of a Chloroplast • Smooth outer membrane • Inside: stacks of connected sacs called thylakoids • One thylakoid stack—granum (grana plural) • Gel-like material around the grana--stroma

  8. Function of Stroma • Light independent reaction • ATP makes glucose • Calvin cycle

  9. Function of Thylakoid Membrane • Light dependent reaction • Made up of chlorophyll molecules

  10. Photosynthesis Equation

  11. Photosynthesis Overview

  12. Light Dependent Reactions • Occurs across the thylakoid membranes • Uses light energy • Produces oxygen from water • Converts ADP to ATP • Converts NADP+ to energy carrier NADPH

  13. Steps of the Light Dependent Reaction • Photosystem II absorbs light energy • Electrons are energized and passed to the Electron Transport Chain (ETC) • Lost electrons are replaced from the splitting of water into 2 H+ , free electrons and oxygen • 2 H+ pumped across the thylakoid membrane

  14. More.. • High energy electrons move to photosystem I through the electron transport chain • Energy is used to transport H+ from stroma to inner thylakoid membrane • NADP picks up 2 electrons from the ETC and a H+ to form NADPH • As H+ ions pass through the thylakoid, ATP synthase binds them to ADP to form ATP

  15. Summary • Reactants: • Water, light • Products • ATP, NADPH—energy for dark reaction • Oxygen—by product for cellular respiration

  16. Light Independent Reaction • ATP and NADPH from light reaction are used for energy of this reaction • CO2 from the atmosphere is used to make sugars (glucose) • Six carbon sugars made in calvin cycle • Occurs in stroma

  17. The Calvin Cycle • Two turns of the Calvin Cycle are required to make one molecule of glucose • 3-carbon dioxide molecules enter the Calvin Cycle to form PGA • Two molecules of PGA form 1 molecule of glucose

  18. DONE!

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