1. Photosynthesis Ch. 10

2. Photosynthesis has two stages: Light reactions energy from the sun is absorbed and converted into ATP Water molecules are split and NADP + picks up the free hydrogen and electrons to make NADPH Takes place in the thylakoid membrane system Calvin Cycle ATP gives energy to sites where glucose (C 6 H 12 O 6 ) is formed NADPH delivers hydrogen CO 2 donates carbon and oxygen Takes place in the stroma

4. Photoautotrophs can only harness the wavelengths between 400 and 750 nanometers. This is also the range of visible light.

5. Pigments are the “molecular bridge” Absorb wavelengths of light and organisms use them Chlorophylls are the main pigments of photosynthesis Absorb all wavelengths except very little of the green and yellow-green ones

8. How do pigments work? Each pigment has a light-catching set of atoms Electrons of a pigment’s light-catching area absorb photons (packets of light energy) Electrons move to higher energy level, then back down  releasing energy The energy is passed on to “neighbors” called a photosystem Energy is passed on and on until it reaches the “reaction center”

11. SUMMARY 3 Things happen in light reactions Pigments of photosystems absorb photon energy and give up excited electrons Transfers of electrons and hydrogen through electron transport systems leads to ATP and NADPH formation Pigments that gave up electrons get electron replacements

12. Noncyclic Photophosphorylation

14. Cyclic Photophosphorylation

16. Calvin Cycle “Synthesis” part of photosynthesis ATP provides energy for the reactions NADPH supplies the hydrogen and electrons CO 2 provides the carbon and oxygen RESULT: sugar

18. C4 Plants Modified for DRY environments Thrive in hot/sunny environments Modified anatomy that allows them to minimize excess water loss and maximize sugar production Pump CO 2 deep into leaf in bundle-sheath cells before going though Calvin Cycle This way, oxygen doesn't inhibit the Calvin Cycle Get away with having smaller stomata, thus losing less water

20. CAM Plants Also adapted to dry conditions Keep stomates closed during the day and open at night This is the reverse of how most plants behave Fixes CO 2 at night and stores materials to use for photosynthesis the next day (when stomata close)