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Autotrophs
- primary producers in ecosystems
- store solar energy in sugars
- First source of organic compounds
- make their own food
- require CO2, H2O, light
- --specifically photoautotrophs vs. chemoautotrophs
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Leaf structure
- "Middle" leaf tissue captures light
- gases enter/exit leaf via stomata (pores)
- Water absorbed by roots, transported to leaf
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Chloroplast structure
- Chloroplasts found in leaf mesophyll
- All green parts of the plant have chloroplast
- Chlorophylls absorbs light energy
- Two outer membranes
- -small intermembrane space
- Stroma-internal fluid
- -DNA, ribosomes, enzymes
- Thylakoids
- -Internal membrane system with flattened sacs. Thylakoids can be in stacks (granum)
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Summary Equation for Photosynthesis
- 6 CO2 + 6H2O + Light -> C6H12O6 + 6O2
- -equation is reverse of respiration, not the reverse for respiration.
- Water is split and O2 is released
- Carbon in CO2 fixed in sugar (glucose)
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Role of light energy and water
- light reactions require light energy
- Light energy excites chlorophyll
- Chlorophyll loses electron
- NADP+ is electron acceptor
- -reduced to NADPH
- Water is split
- Replaces chlorophyll electron, O2 released.
- ATP produced via photophorosphorylation
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Electron flow and reduction
- Linear Electron Flow
- Photosystems help synthesize NADPH & ATP
- 1. Light absorbed by PS II pg 680, e- released
- 2) Excited electron captured by 1degree acceptro
- 3) Water split to replace PS II electron
- -oxygen is created as a byproduct
- 4) Electron moves to PS I
- -via an electron transport chain
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