2. AP Biology Photosynthesis: Life from Light Adapted from Ms. Lisa Miller’s AP Biology Notes.

3. AP Biology How are they connected? glucose + oxygen  carbon + water + energy dioxide C 6 H 12 O 6 6O 2 6CO 2 6H 2 OATP  +++ Heterotrophs and Autotrophs + water + energy  glucose + oxygen carbon dioxide 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy  +++ Autotrophs making energy & organic molecules from light energy making energy & organic molecules from ingesting organic molecules Where ’ s the ATP?

4. AP Biology 2005-2006 Plant Structure Obtaining Raw Materials  Sunlight  Leaves = solar collectors  Mesophyll cells have a large number of chloroplasts.  CO 2  Stomata= gas exchange  Found under leaves  H 2 O: uptake from roots.  Nutrients: uptake from roots.

5. AP Biology  Chloroplasts  Double membrane  Stroma  Thylakoid sacs  Grana stacks  Part of photosynthesis occurs in the thylakoid membrane. Plant Structure H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+

6. AP Biology 2005-2006 Pigments of Photosynthesis  Chlorophyll and Accessory Pigments  Embedded in thylakoid membrane.  Structure  Function Why does this structure make sense?

7. AP Biology Light: Absorption Spectra  Photosynthesis gets energy by absorbing wavelengths of light.  Chlorophyll a (dominant pigment)  Absorbs best in red & blue wavelengths.  Absorbs least in green.  Other pigments with different structures absorb light of different wavelengths. Why are plants green?

8. AP Biology Photosynthesis  Light Reactions  Light-dependent Reactions  Energy production reactions.  Convert solar energy to chemical energy.  Calvin Cycle  Light-independent Reactions  Sugar production reactions. It ’ s the Dark Reactions!

9. AP Biology Photosystems  2 photosystems in thylakoid membrane.  Act as light-gathering “antenna complex.”  Photosystem II: chlorophyll a  Photosystem I: chlorophyll b reaction center Energy is passed to the primary electron acceptor, which removes an excited electron form the chlorophyll.

10. AP Biology The Light Reaction 2005-2006

11. AP Biology 2005-2006 From Light Reactions to Calvin Cycle  Calvin cycle  Location: chloroplast stroma.  Need products of light reactions to drive synthesis reactions.  ATP  NADPH What is there left to do? Make sugar!

12. AP Biology From CO 2  C 6 H 12 O 6  CO 2 has very little chemical energy.  C 6 H 12 O 6 contains a lot of chemical energy.  The reaction of CO 2  C 6 H 12 O 6 proceeds in many small uphill steps.  Each catalyzed by specific enzyme.  Using energy stored in ATP and NADPH.

13. AP Biology Calvin Cycle 2005-2006

14. AP Biology Summary  Light Reactions:  produced ATP  produced NADPH  consumed H 2 O  produced O 2 as by product  Calvin Cycle:  consumed CO 2  produced glucose  regenerated ADP  regenerated NADP ADPNADP

15. AP Biology Factors that affect Photosynthesis  Enzymes are a part of photosynthesis, therefore, temperature and pH can affect the rate of photosynthesis.  The amount and type of light can affect the rate.  A shortage of any of the reactants,CO 2 and/or H 2 O, can affect the rate.

16. AP Biology Supporting a biosphere On global scale, photosynthesis is the most important process for the continuation of life on Earth.  Each year photosynthesis synthesizes 160 billion tons of carbohydrate.  Heterotrophs are dependent on plants as food source for fuel & raw materials.

17. AP Biology Energy cycle Photosynthesis Cellular Respiration glucoseO2O2 H2OH2OCO 2 ATP sun The Great Circle of Life! Where ’ s Mufasa?

18. AP Biology 2005-2006 Summary of photosynthesis  Where did the CO 2 come from?  Where did the CO 2 go?  Where did the H 2 O come from?  Where did the H 2 O go?  Where did the energy come from?  What’s the energy used for?  Where did the O 2 come from?  Where will the O 2 go? 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy  +++