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Photosynthesis

Photosynthesis. What are autotrophs? Why are they important?. . Energy for Life. AUTOTROPHS are organisms that can make their own food . Also called PRODUCERS . Ex. PLANTS, ALGAE. . Energy for Life. HETEROTROPHS are organisms that depend on other organisms for food .

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Photosynthesis

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  1. Photosynthesis

  2. What are autotrophs? • Why are they important?

  3. Energy for Life • AUTOTROPHS are organisms that can make their own food. • Also called PRODUCERS. • Ex. PLANTS, ALGAE

  4. Energy for Life • HETEROTROPHS are organisms that depend on other organisms for food. • Also called CONSUMERS. • Ex. ANIMALS, BACTERIA

  5. Energy for Life • TWO biological processes are needed to create usable energy for organisms. • Photosynthesis– the process that converts sunlight into sugar. (autotrophs only) • Respiration – process that releases energy in sugar into usable energy for cells. (autotrophs and heterotrophs)

  6. ATP • Adenosine triphosphate (ATP) – energy storage molecule. Adenine (nitrogen base) Ribose (sugar) 3 Phosphate groups

  7. ATP ADP + phosphate + energy (tri) (di) ATP • ATP is the universal currency for energy • ATP stores energy in the BONDS BETWEEN THE PHOSPHATE GROUPS. • When a BOND IS BROKENenergy is released.

  8. Structure of a Chloroplast • A chloroplast is the structure in a plant cell where photosynthesis occurs. Internal Structure: • Thylakoid membrane –internal membrane, look like stacks of pancakes. • Lumen – space inside thylakoid membrane. • Grana –stacks of thylakoids. • Stroma – solution that thylakoids are embedded in.

  9. Structure of a Chloroplast

  10. Pigments • Pigments are light absorbing molecules. • Each pigment absorbs and reflects different wavelengths of light. (we see the reflected color)

  11. Pigments • CHLOROPHYLL is the primary pigment in photosynthesis. • Gives plants their GREEN color. • CAROTENOIDS are accessory pigments that absorb light that chlorophyll cannot. • They are YELLOW, ORANGE, AND BROWN.

  12. Checkpoint • Why do leaves turn yellow, orange and brown in the fall? • Production of chlorophyll is slowed down in the fall due to lower temperatures and less sunlight!

  13. Pigments

  14. 6 CO2 + 6 H2O + sunlight C6H12O6 + 6O2 Photosynthesis song :) Photosynthesis Sunlight Glucose Carbon Dioxide Oxygen Water 

  15. Van Helmont • Measured plant mass and soil mass before and after 5 years of growth • Most of gain in mass came from water

  16. Priestly • Candle with a jar over it would die out • Required oxygen • Sprig of mint plus candle caused candle to last longer • Plant produced oxygen

  17. Ingenhousz • Effect showed by Priestly occurred only in the presence of light

  18. Photosynthesis • There are two stages to photosynthesis, the light-dependent reactions and light-independent (dark) reactions. Photosynthesis video

  19. Light-dependent Reactions • Occur in the THYLAKOID MEMBRANES. • Light is absorbed by chlorophyll in Photosystem II and electrons are excited. • The excited electrons move through a series of reactions – the electron transport chain.

  20. Light-dependent Reactions

  21. Light-dependent Reactions • The light energy splits water molecules into H and O2 • The O2 is released into the atmosphere and the H bonds to a carrier molecule (NADPH) to be carried to the Dark Reactions. • Splitting the water also creates ATP.

  22. Sunlight, water, and CO2 Chloroplast Light- dependent Reactions Light Reactions Chloroplast Light Reactions ATP ATP ATP NADPH NADPH NADPH O2 The end products of the light reactions are NADPH, ATP, and O2

  23. Melvin Calvin Light-independent Reactions • Don’t Require LIGHT • Also called the DARK REACTIONS OR THE CALVIN CYCLE. • Occur in the STROMA

  24. Light-independent Reactions • Carbon dioxide enters the plant and attaches to a sugar molecule. • This is called carbon fixation • Carbon Dioxide, NADPH, and ATPcombine with enzymes to make glucose (C6H12O6) and more CO2.

  25. Light, water, and CO2 Carbon Fixation ATP NADPH+H O2 Dark Reactions CO2 Chloroplast Chloroplast NADP+ ADP + P Light- independent Reactions Light- dependent Reactions Glucose

  26. Factors Affecting Photosynthesis • Light Intensity– the more light the faster the rate of photosynthesis. • CO2 Concentration– the more CO2, the faster the rate of photosynthesis. • Temperature – rate of photosynthesis slows down at extremes of hot or cold. Photosynthesis video

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