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Photosynthesis

Photosynthesis. Is defined as… A process by which light energy is converted into chemical energy Where does this take place? In the chloroplasts of plant cells. The Basics: Reactants and Products. The main source of energy for all life is…. The SUN

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Photosynthesis

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  1. Photosynthesis • Is defined as… • A process by which light energy is converted into chemical energy • Where does this take place? • In the chloroplasts of plant cells

  2. The Basics: Reactants and Products

  3. The main source of energy for all life is…. • The SUN • Photosynthesis is the process of converting sunlight into ATP then into organic molecules that store energy.

  4. ATP • How is ATP like money? • It is: Energy currency -- the only form of energy living things can use (spend). • How does ATP release energy? • By breaking the bond between the 2nd and 3rd phosphate and becoming ADP.

  5. Autotrophs are… Plants or other organisms that make their own energy from the sun or inorganic compounds (they are producers) • Heterotrophs are consumers that… • Get energy from food by eating plants and animals that eat plants

  6. Where are the stroma and thylakoid space relative to the thylakoid membrane? • The chloroplast contains thylakoids in a fluid-filled space called the stroma. • The thylakoid space is inside the thylakoid and the membrane surrounds it.

  7. Where is chlorophyll located? • On the thylakoid membrane • What is chlorophyll? • A pigment that absorbs and reflects light

  8. What are the three products of photolysis? • 1 Oxygen to the atmosphere • 2 H+ ions inside the thylakoid membrane • 3 Electrons to chlorophyll to replace those lost to the ETC

  9. What frequencies of light are absorbed and reflected by chlorophyll? • Red and blue are absorbed • Green is reflected

  10. What happens to chlorophyll when it absorbs light energy? • It loses excited electrons to the electron transport chain. • How are these electrons replaced? • Photolysis= light splitting water with an enzyme.

  11. Describe the ETC:electron transport chain. • A series of protein molecules embedded on the membrane where each one has a higher attraction for electrons than the previous one.

  12. What happens as the energy is released in each redox reaction? • This energy is used to actively transport H+ ions into the thylakoid space against the gradient. • This builds up a higher concentration of H+ in the thylakoid space.

  13. Are H+ freely permeable to the thylakoid membrane? (can they cross easily?) • No-- they are charged! • How do H+ ions diffuse out of the thylakoid space into the stroma? • Through a transport protein called… • ATP Synthetase

  14. Is the flow of H+ ions through ATP Synthase “energy requiring” or “energy releasing”? • Energy releasing • This energy is used to form ATP

  15. Is the formation of ATP energy requiring or energy releasing? • Energy requiring • Energy is needed to create the bond between the 2nd and 3rd phosphate making ATP from ADP + P

  16. What serves as the final electron acceptor at the end of the electron transport chain? • NADP+ • What happens to create NADPH? • NADP+ combines with the final e- and H+ from the stroma to make NADPH. • NADPH is used in the next phase.

  17. What three things are needed for the light reactions? What three things are produced in the light reactions? • Needed--Light, water, chlorophyll • Produced--oxygen (to atmosphere), ATP, and NADPH (to dark reactions)

  18. The dark reactions, AKA -- the light independent reactions, are also known as… • The Calvin Cycle • What is carbon fixation and where does the carbon come from? • CO2 from the air is added to a 5 Carbon sugar = this is “carbon fixation” • Glucose is produced

  19. What is NADPH used for? • It carries electrons and H+ ions to the Calvin Cycle. • These are used to build glucose molecules. • What enzyme is key to this process? • Rubisco

  20. Explain the results of the Photosynthesis Lab • What light treatments had the highest and the lowest rate of reaction? • What role did DPIP (blue stuff) play in the photosynthesis reaction?

  21. Now that you know all about photosynthesis.. • Don’t forget to hug a tree! • Without photosynthesis, we would not have air to breath or food to eat. • THE END ?

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