http://web.pdx.edu/~rueterjesr473/notes/photosynthesis-overview.htm
This section will focus on the light and dark reactions of photosynthesis. We will catalog the biochemical composition of these two components of cell machinery and follow the reactions that tie them together. This section will introduce the important concept of "optimization" in relationship to the relative amounts of the photosynthetic membrane to the photosynthetic enzymes. We will expand on optimization in subsequent sections. We will examine the overall output of photosynthesis as a function of light and work with the equations and graphs that describe this relationship. You should reach an understanding for intraspecific and interspecific variations in photosynthetic component content as it relates to photosynthesis output.
pigments absorb light energy
transformed to chemical forms (ATP and NADPH)
passed to enzymatic, RPPP cycle synthesis of triose
some energy used for reductive assimilation of nitrogen sources
trioses are both stock for synthesis and to provide energy for respiration
adaptation through differentical synthesis
see the list under biochemical composition
PSII
plastoquinone
cytb6f complex
PSI
coupling factor
RuBisCO
Reductive Pentose Phosphate Pathway enzymes
photosynthesis contains several types of energy transduction
photon capture to form excited molecules
resonance transfer of energy
fluorescence loss of energy
charge separation (voltage potential of the e-)
proton pumping in the thylakoid membrane
chemiosmotic production of ATP
reduction of Fd and NADPH
reduction rxns in RPPP
light dependent reactions (photon to NADPH, Fd(red) and ATP)
RPPP CO2 + NADPH + ATP --> reduced carbon (as TrioseP)
associated storage reactions (glycogen and starch)
photorespiration (RuBP + O2 --> 2C and 3C + rearrangement of these)
photoinhibition (light dependent inhibition of photosynthesis that takes protein synthesis to reverse)
P vs. I
Pmax, Ik, I0
Blackman model
tanh model - Pmax, alpha, beta, respiration
substrate level control by NADPH and NADP+
roles of ferredoxin and ions in regulation in the chloroplast
activation of RPPP enzymes
balance of flow from light dependent to light-independent reactions
2 component model - increase limiting component (photo-memb or RPPP enzymes)
examples of how cells have more or less of photosynthetic membranes or RPPP enzymes in adaptation to low or high light respectively
April 10, 2000