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overview on light dependent reactions (2)
-transform energy in sunlihgt to chemical energy
-excited electrons either produce NADPH or are donated to ETC which produces ATP
Light independent reactions
-starts eith enzyme rubisco that catalyzes the addition of CO2 to a five carbon molecule that ultimately resutls in production of sugar
-light dependent reactions produce chemical energy (ATP- NADPH)
-chemical energy is used with light independent reactions to produce chemical energy (glucose)
HOw many chloroplasts in each cell?
stack of thylakoids
cytoplasm like subsatnce
Red waves (2)
-has less energy
-larger wave length
Blue waves (2)
-has more energy
Where do light dependent reactions occur?
Where do light independent reactions occur?
When light is absorbed...
electron enter an excited state
Carotenoids and free radicals
Carotenoids act to quench free radicals by accepting or stabilizing unpaired electrons
Why are plants green? (2)
-there is a heavier presence of chlorophylls
-and they cannot absorb green light
What 2 colors do chlorophylls absorb best?
blue and red light
What 2 colors do carotenoids absorb best?
blue and green light
How to isolate pigments using paper chromatography? (3)
- 1. grind leaves and add organic solvent
- *pigment molecules move from leaves into solvent
2. Spot pigments on filter paper
3. Seperate pigments in solvent
What is absorption spectrum
it is what a particular chemical absorbs
What is action spectrum
- it is what absorbed lights produce a response
- *pigments that absorb blue and red light are most effective at triggering PS
-hydrophobic tail plays a role in keeping parts of chlorophyll in a membrane
-business end of molecule: Metal ion in the center held down by nitrogen
-ring struture in head absorbs light
What is the only difference between CHlorophyll a and b?
A has CH3 and B has CHO
What happens if small changes in the ring happen?
it dictates what types of wavelengths it can absorb
- Absorbs photon, raises electron to a new energy level
- -then electron goes back to a lower level
- *as it goes down it gives off a photon of light that is lower in energy
- -HAs no consequence as far as PS is concern
- *dead end reaction
-photon is absorbed by one chlorophyll molecule
- -electron hops to one to the other
- *all chlorophylls are connected by antena complex
-There is an area called reaction center,
where the electron will be promoted then given off somewhere
-excited electron will be handed off to a different molecule called electron acceptor
At the reaction center, excited electrons are usually passed to...
- an electron acceptor
- *usually phenophylin
-pheophytin takes excited electron and passes it off to PQ.
- -PQ then takes molecule and hands it off to other proteins in cytochrome complex
- *PQ and cytochrome complex are ETC