Lecture 28 Flashcards
Why arent leaves green in the fall
chlorophyll a and b are expensive to make so they cant always be green when they don’t have enough energy to make them
What makes leaves red/orange in fall
ß-carotene and xanthophylls accessory pigments that protect plants from the intense light that don’t break down in fall
they reflect orange/red into our eyes
How do accessory pigments like ß-carotene and xanthophylls protect plants against sunburn
they absorb light and extra electrons to convert energy into heat that radiates away from the plant, preventing the plant from being overworked
Basic overview of photosystem transporting electrons to make h+ proton gradient
H2O is broken to return the electron to the special P680 chlorophyll molecule that donated its electron to the transport chain H+ and oxygen is released
PSII is surrounded by light-harvesting complexes (LHC II) that move around based on lighting conditions
Complete photosynthetic electron transport system generates what
generates H+ for ATP synthesis and NADPH for driving sugar production
Complete parts of photosynthesis electron transport system
Photosystem II and Photosystem I
Photosystem I steps
Electron from PC transported into the P760
Electron from P760 transported to Fd (ferredoxin)
electron from Fd goes to FNR (ferredoxin-NADP+ reductase) releasing NADPH with electrons
Enzymes involved in Photosystem II
Qb (plastoquinone)
QbH2 (reduced plastoquinol)
Cut b/f (cytochrome b/f)
PC (plastocyanin)
Enzymes involved in Photosystem I
Fd (ferredoxin)
FNR (ferredoxin-NADP+ reductase)
NADPH (essential reducing agent for many anabolic pathways)
In the photosynthetic transport system, what does it do if extra ATP is needed
FNR can send electrons back into Cyt b/f to increase H+ proton gradient
Where is does the electron transport and proton pumping occur during photosynthesis
in the granum
where does the ATP synthesis occur or where does the ATP get released and where carbon assimilation occurs
in the stroma
The Calvin cycle is
carbon fixation, conversion of atmospheric carbon into covalent bonds of organic molecules used by the cell
Calvin cycle stages
- Carbon added to ribulose acceptor molecule
- reduction by NADPH to G3P (glyceraldehyde 3-phosphate)
- regeneration of the original ribulose acceptor molecule
Ribose vs ribulose
ribulose has CH2OH instead of O and H
