Photosynthesis Flashcards
Biomass Partitioning
TBD
Biomass Accumulation
Everything the plant takes up and doesn’t give back
Location of the light reactions?
Thylakoids inside the chloroplasts
Location of Calvin cycle
Stroma inside the chloroplast
-liquid around thylakoids but inside chloroplast
Granum/Grana
Layers of thylakoids
400nm? To 700nm?
400= violet 700= red
Chlorophyll a color absorbance
425 violet-blue and 675 low red
Approximately (at peaks)
Chloroplast b absorbance
475nm blue. 635 yellow to low red
Approximately (at peaks)
Carotenoids absorbance
2 peaks from 450 to 500
Violet and blue
“Action Spectra”
Peaks at violet-blue and low red
Lowering in the green-yellow area.
Light absorbing head
Porphyrin ring chlorophyll a & b head with hydrocarbon tail for stability
Green heads in diagram as light receptors
PAR
Photosynthetically active radiation
General light reaction process for NADP+
Light @PSII -> Pq -> cytochrome complex -> Pc -> PSI (light) ->
Fd -> NADP+ reductase (NADP+ + 2H+ + e- = NADPH + H+)
General light reactions for ATP
H2O splits at PSII -> 2H+ increases concentration -> cytochrome brings in 2H+ from stroma to lumen -> high concentration runs ATP Synthase (ADP+ P goes trough “pump” to produce ATP)
Step 1) light
Light is absorbed by the porphin ring at PSII. 1 photon excites 1 electron to higher energy state. Water (H2O) is split by the excited e-. Oxygen is released as a byproduct and 2H+ accumulates in the lumen to add to the proton gradient to power ATP Syntase.
Step 2) Pq
Plastoquinone: transports e- from PSII to he cytochrome complex
Step 3) cytochrome complex
Cytochrome complex brings 2H+ from stroma to lumen for proton gradient.
Step 4) Pc
Plastocyanin: Transports the e- from cytochrome complex to PSI
Step 5) PSI
PS1 absorbs light to reexcite the e- and increase its energy level.
Step 6) Fd
Ferredoxin: transports e- from PSI to NADP+ reductase
Step 7) NADP reductase
NADP+ + 2H+ uses the excited e- for energy to produce NADPH + H+ THEN—> NADPH is used in Calvin Cycle.
Step 8) ATP Synthase
The proton gradient created by the 2H+ from water splitting at PSII and from the cytochrome complex pull it from the stroma runs the ATP Synthase like a “mechanical pump”. ADP + P goes through the ATP Synthase to produce ATP.
Calvin Cycle: Phase One
Carbon Fixation: Rubisco takes carbon from CO2 and adds it to Ribulose bisphosphate (RuBP) to become 3-PGA. ATP is used to form 1,3-Bisphosphoglycerate and ADP is released.
Calvin Cycle: Phase 2
Reduction: The 1,3-Bisphosphoglycerate interacts with NADPH to form G3P and returns NADP+. Then 1 G3P goes to output for glucose and other organic compounds while 5 G3P continue in the cycle.
