1. Photosynthesis
Chapter 7
Mader: Biology 8th Ed.

2. Photosynthetic Pigments Photosynthesis Light Reactions Noncyclic
Outline
Flowering Plants
Photosynthetic Pigments
Photosynthesis
Light Reactions
Noncyclic
Cyclic
Calvin Cycle Reactions C4
CAM
Mader: Biology 8th Ed.

3. Photosynthetic Organisms
Photosynthesis transforms solar energy into the chemical energy of a carbohydrate.
All organisms use organic molecules produced by photosynthesizers as a source of chemical energy.
Mader: Biology 8th Ed.

4. Leaf of flowering plant contains mesophyll tissue.
Flowering Plants
The green portions of plants, particularly leaves, carry on photosynthesis.
Leaf of flowering plant contains mesophyll tissue.
Contains cells specialized to carry on photosynthesis.
Mader: Biology 8th Ed.

5. CO2 enters leaf through stomata.
Flowering Plants
CO2 enters leaf through stomata.
CO2 and water diffuse into chloroplasts.
Double membrane surrounds fluid (stroma).
Inner membrane system within stroma form flattened sacs (thylakoids).
Often stacked to form grana.
Chlorophyll and other pigments within thylakoid membranes are capable of absorbing solar energy.
Mader: Biology 8th Ed.

6. Photosynthetic Pigments
Most pigments absorb only some wavelengths of light and reflect or transmit the other wavelengths.
Absorption Spectra
Organic molecules and processes within organisms are chemically adapted to visible light.
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7. Photosynthetic Pigments and Photosynthesis
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8. Photosynthetic Reaction
Light Reaction - Chlorophyll absorbs solar energy and energizes electrons.
Electrons move down electron transport chain.
Solar energy  ATP, NADPH
Calvin Cycle Reaction - CO2 is taken up and reduced to a carbohydrate.
Reduction requires ATP and NADPH.
ATP, NADPH  Carbohydrate
Mader: Biology 8th Ed.

9. Photosynthesis Overview
Mader: Biology 8th Ed.

10. Light reactions consist of two electron pathways:
Noncyclic electron pathway
Cyclic electron pathway
Both pathways produce ATP, but only the noncyclic pathway also produces NADPH.
Mader: Biology 8th Ed.

11. Noncyclic Electron Pathway
Electron flow can be traced from water to a molecule of NADPH.
Uses two photosystems, PS I and PS II.
Photosystem consists of pigment complex and electron acceptor molecules in the thylakoid membrane.
Pigment complex helps gather solar energy.
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13. Cyclic Electron Pathway
Cyclic pathway begins when PS I pigment complex absorbs solar energy and is passed from one pigment to another until it is concentrated in a reaction center.
Pathway only results in ATP production.
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15. Thylakoid Organization
Mader: Biology 8th Ed.

16. Calvin Cycle Reactions
Calvin cycle is a series of reactions that produce carbohydrates before returning to the starting point again.
Utilizes atmospheric carbon dioxide to produce carbohydrates. Includes:
Carbon dioxide fixation
Carbon dioxide reduction
RuBP Regeneration
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17. Mader: Biology 8th Ed.

18. Calvin Cycle Reactions
Carbon Dioxide Fixation
CO2 is attached to RuBP. The result is a 6-carbon molecule which splits into two 3-carbon molecules.
Rubisco speeds up this reaction.
Mader: Biology 8th Ed.

19. Calvin Cycle Reactions
Reduction of Carbon Dioxide
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20. Calvin Cycle Reactions
Regeneration of RuBP
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21. Importance of Calvin Cycle
PGAL (glyceraldehyde-3-phosphate) is the product of the Calvin cycle that can be converted to a variety of organic molecules.
A plant can utilize the hydrocarbon skeleton of PGAL to form fatty acids and glycerol, which are combined in plant oils.
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23. Avoid photorespiration
C4 Photosynthesis
In C4 leaf, bundle sheath cells and mesophyll cells contain chloroplasts.
Mesophyll cells are arranged concentrically around the bundle sheath cells.
In hot, dry climates, net photosynthetic rate of C4 plants is about 2-3 times that of C3 plants.
Avoid photorespiration
Mader: Biology 8th Ed.

24. C3 vs C4
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25. Carbon Dioxide Fixation in C3 and C4 Plants
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26. Crassulacean-Acid Metabolism
CAM Photosynthesis
Crassulacean-Acid Metabolism
C4 plants partition carbon fixation in space, while CAM partitions by time.
During the night, CAM plants fix CO2, forming C4 molecules, which are stored in large vacuoles.
C4 molecules release CO2 to Calvin cycle when NADPH and ATP are available.
Water Conservation
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27. Mader: Biology 8th Ed.

28. Photosynthetic Pigments Photosynthesis Light Reactions Noncyclic
Review
Flowering Plants
Photosynthetic Pigments
Photosynthesis
Light Reactions
Noncyclic
Cyclic
Calvin Cycle Reactions C4
CAM
Mader: Biology 8th Ed.

29. Mader: Biology 8th Ed.