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Photosynthesis

Photosynthesis. Chapter 8. Energy and Life 8-1. Energy The ability to do work Without the ability to obtain and use energy, life would cease to exist. Energy and Life 8-1. Autotrophs Organisms that make their own food Plants

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Photosynthesis

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  1. Photosynthesis Chapter 8

  2. Energy and Life 8-1 • Energy • The ability to do work • Without the ability to obtain and use energy, life would cease to exist

  3. Energy and Life 8-1 • Autotrophs • Organisms that make their own food • Plants • Plants and some other types of organisms are able to use light energy from the sun to produce food

  4. Energy and Life 8-1 • Heterotrophs • Organisms that obtain energy from the food’s they consume • Ex. Animals • Animals and some other organisms cannot use the sun’s energy directly • Some eat autotrophs • Some eat other animals • Some decompose other organisms

  5. Energy and Life 8-1 • Chemical energy and ATP • ATP - Adenosine Triphosphate • One of the principle chemical compounds that cells use to store and release energy • Consists of adenine, ribose, and 3 phosphate groups

  6. Energy and Life 8-1 • Storing Energy • ADP • Adenosine diphosphate • Two phosphates instead of three phosphates • Adding a phosphate to ADP produces ATP • ADP  ATP

  7. Energy and Life 8-1 • Releasing Energy • The characteristics of ATP make it exceptionally useful as the basic energy source of all cells • ATP  ADP

  8. Energy and Life 8-1 • Uses Biochemical Energy • Active Transport • Sodium-potassium pump • Pumps sodium out of and potassium into the cell • Cellular movement • Organelle functioning • Organelle movement within the cell • Storage • ATP is not good at storing energy • Glucose is better than ATP for long term storage • 90 times more energy

  9. Photosynthesis 8-2 • Investigating Photosynthesis • Photosynthesis • Plants use the sunlight to convert water and carbon dioxide into carbohydrates and oxygen

  10. Photosynthesis 8-2 • Van Helmont’s Experiment • Where does the mass of a tree come from? • The mass comes from the water • Soils mass was nearly unchanged • Water was the only thing added • Other things were not taken into consideration by Van Helmont

  11. Photosynthesis 8-2 • Priestly’s Experiment • Lit candle in a jar experiment • Flame gradually went out • Something in the air allowed the candle to burn • What was this substance?

  12. Photosynthesis 8-2 • Priestly – Part 2 • He placed a mint leaf in one jar and the candle in another • Mint plant allowed the flame to last much longer • Mint plant produced something that the candle flame required • What was this substance?

  13. Photosynthesis 8-2 • Jan Ingenhousz Experiment • Lit candle in a jar with mint plant and no light • Flame did not last as long as with mint plant in light • What does this demonstrate? • Light is necessary for plants to produce oxygen!

  14. Photosynthesis 8-2 • Photosynthesis Equation • 6CO2 + 6H2O + (light)  C6H12O6 + 6O2 • Carbon Dioxide + Water (with light)  Sugars + Oxygen

  15. Photosynthesis 8-2 • Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen

  16. Photosynthesis 8-2 • Light and Pigment • The equation tells you what is needed, BUT not what happens • Photosynthesis requires light and a substance called chlorophyll • Found in chloroplasts • Makes plants look green

  17. Photosynthesis 8-2 • Sun’s energy travels to Earth as light • Pigments are molecules that absorb light • Chlorophyll is the main pigment in plants • Why are plants green? • Plants absorb all of the light spectrum except for green • The light that is absorbed is converted to energy in the electrons of the chlorophyll

  18. Photosynthesis 8-2 • Not all plants are green…How? • Two different types of chlorophyll • Chlorophyll α • Chlorophyll β • The difference in plant colors is due to the amount of these pigments

  19. The Reactions of Photosynthesis 8-3 • Inside a Chloroplast • The organelle where photosynthesis takes place • Thylakoid • Saclike photosynthetic membranes • Grana (Granum) • Stacks of thylakoids • Photosystems • Clusters of pigment and protein that absorb light energy • Stroma • Area outside of the thylakoid in the chloroplast

  20. The Reactions of Photosynthesis 8-3

  21. The Reactions of Photosynthesis 8-3 • Electron Carriers • Electron Transport Chain • Transports the electrons between photosystems • Transport high-energy electrons to other molecules • Electrons gain energy from sunlight • These electrons exist inside the chlorophyll • Something has to be done with these electrons

  22. The Reactions of Photosynthesis 8-3 • NADP+ • Chloroplasts trap energy from the sun • Two electrons and a hydrogen molecule make NADPH • NADPH can move to other parts of the cell and make things like glucose

  23. The Reactions of Photosynthesis 8-3 • Light-Dependent Reactions • Produce oxygen gas and convert ADP and NADP+into the energy carriers ATP and NADPH

  24. The Reactions of Photosynthesis 8-3 • Photosystem II pigments absorbs light • Light absorbance excites electrons to a higher energy level • High-energy electrons move to the electron transport chain • Thylakoid replaces lost electrons from stored water • Two hydrogen molecules (New Electrons) • One oxygen (Waste)

  25. The Reactions of Photosynthesis 8-3 • High-energy electrons move from photosystem II to photosystem I • Energy from the electrons is used to move hydrogen ions from the stroma to the inner thylakoid space

  26. The Reactions of Photosynthesis 8-3 • Photosystem I uses light to reenergize the electrons • NADP+ picks up the high-energy electrons and hydrogen ions to make NADPH

  27. The Reactions of Photosynthesis 8-3 • Hydrogen ions are pumped across the thylakoid membrane • This happens until the inside of the thylakoid is positive and the outside is negative • This results in energy that can be used to make ATP –the useable form of energy for the plant cell!

  28. The Reactions of Photosynthesis 8-3 • Hydrogen ions cannot pass through the thylakoid membrane directly • ATP synthase – membrane protein • Allows hydrogen to pass through • ATP synthase will bind ADP and phosphate  ATP

  29. The Reactions of Photosynthesis 8-3 • Summary of light reactions: • Water breaks down - hydrogen ions and oxygen • NADP+ becomes NADPH – electrons and hydrogen ions to photosystem I • ADP to ATP via ATP synthase • YEAH!!! We have ATP, now what?

  30. The Reactions of Photosynthesis 8-3 • Calvin Cycle • Uses ATP and NADPH from the light dependent reactions to produce high-energy sugars • Does NOT require light to proceed – it uses the energy captured from the light reactions. • This is where carbon dioxide (CO2) is used.

  31. The Reactions of Photosynthesis 8-3 • Factors affecting photosynthesis • H2O • Plants require water for photosynthesis to occur • Dry conditions - waxy covering • Temperature • Enzymes require temperature range of 0o – 35o C • Light Intensity • The more light the more photosynthesis to a point

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