Photosynthesis Flashcards
Why do we use biooptics
Understand marine PP wrt size and variability of production and ecosystem structure
Reliable estimations of global marine PP (but be aware of sampling limitations and methodological problems)
Parameter values to predict and understand dynamics PP
What do the bio optical properties in a phyto cell depend on
Pigment composition
Cell size, shape, morphology
Chloroplast size, shape, number, distribution
Degree of stacking and optical properties of thylakoid membranes
Which 4 things can we detect with bio-optical measurments
Pigment composition
Bio-optical characteristics (light harvesting and utilization, taxonomy, biomass)
PS parameters
Changes in physiol. status based on nutrients, temperature, light, salinity
How can HL adapted cells be characterized
Low pigment content High amounf of photoprotective pigments Low amount of LHP High Chla specific absorption High respiration
How can LL adapted cells be characterized
High pigment content Low amount of photoprotective pigments High amoint of LHP Low chla specific absorption Low respiration
What is fluorescence
A molecule absorbs one photon. An electron gets excited, excitation energy is used in PS. Excitation energy is lost by heat release or fluorescence
How much fluorescence is normally emitted and with DCMU
1% under normal in vivo circumstances
3% when PS is limited with DMCU (no electron transport
Why do we use the maxium flashing
To close all reaction centers and thereby eliminate all photochemical quenching. fluorescence rises to a level corresponding to that which would exist without any photochemical quenching
What is inductive resonance
The photon taken up by the molecule excites an electron. The energy is partly lost by re-emission of heat and energy is then transfered by inductive resonance to adjacent pigments. The molecule returns to the ground state.
What does the photosynthetic rate depend on
Available photons absorbed and transported to PS
Conversion of light energy to chemical energy (quantum yield phi)
Amount of Chl a per PSU
Minimum turnover time for electrons in PSU (tau)
How can we calculate the Ek
Divde the Pbm (maximum photosynthetic rate in amount C per chla per h) by the alphaB (amount C fixed per Chla per h per quanta m-2 s-1)
How can we calculate the alphaB (amount C fixed per Chla per h per quanta m-2 s-1)
Phi max (maximum quantum yield) times simga0 (spectral weighted and chla normalized light energy absorped that is utilized by PS)
How can we calculate the Pbm (maximum photosynthetic rate in amount C per chla per h)
Phi max (maximum quantum yield in mol C/O2 per mol quanta) divided by q times tau (chla concentration per PSU in mg chla per mol PSU times minimum turnover time of electron in PSU in hours)
What is the Poisson Probability (PP) and how does it relate to PvsE curves
This is the probability that a photon reaches an open reaction center, has a value of 1 in darkness and 0 in infinite radiance. PvsE curves can be explained as a product of the PP
What influences the Chla fluorescence induction curve (or Kautsky curve)
Light absorption Photochemistry in PSII Electrontransport pH gradient across thylakoid membrane CO2 assimilation Phosphorylation of protein pigment complexes
