review sugar chemistry:

linear form -aldose or ketose number of carbons triose, tetrose pentose, hexose, heptose

pyranose (preferred in watery solutions - furanose

examples glucose fructose ribose (pentose, aldose)

mono saccharide di - , tri-, oligo - and polysaccharides

di - sacch-: reducing / non reducing

sucrose (draw structure) (or +galactose units)

3 phases of Calvin cycle:

   carboxylation

   reduction (NADPH2 &ATP) (3PGA)-> 1,3 biPGA -> 3PGald

   regeneration

 

Reaction types during regeneration:

   isomerase glycald3phos <-> dihydroxydaceton 3P

   aldol condensation (aldolase) e.g.: glycald3phos + dihydroxydaceton 3P -> fru 16 bis phosphate,

   phosphatases (bisP- P),

   transketolase, Fru 6P + glycald3phos -> erythrose 4P + xylulose 5P

   epimerases xylulose 5P -> ribulose 5P

    (ATP) Ribu5P(kinase)

 

3Phosphoglycerate labeled - C-3 photosynthesis

Ribulose bis phosphate carboxlase

regulation by light: thylacoids more acidic and inside + / stroma more alkaline - more Mg

Rubisco carbamate formation

other enzymes act via thiol formation

 

oxygenation reaction:

Photorespiration = energetic loss, no use at all , no ATP synthesized

RubiP - 3PG + phospho glycolate -> glycolate Peroxisome Glyoxylate :alpha keto acid : transaminase -> Glycine -> Mitoch 2 Gly _ Serine + CO2 + NH3 - > HydroxyPyruvate - red to Glycerate -+ ATP-> 3-PGA

 

two cycles with Rubisco a) C3 Calvin cycle 3PGA b) Photorespiration

 

What to do about it?

A) nothing -> C-3 plants

B) accumulate CO2, especially under low CO2 (=low H2O conditions)

 

B1) bicarbonate uptake with active transmembrane transport -- algae (+?water plants)

B2) C4 plants
      first labeled product C4 compound OAA, malate, or Aspartate
      Chloroplast dimorphism - Krantz Anatomy Bundlesheath cell chlorors different green little or no grana
      Calvincycle enzymes
      mesophyll PEP carboxylase (anapleurotic reaction for TCA cycle - liver cells also incorp CO2 into       metabolites (but it does not get reduced to sugar or hydrocarbon)

PEP +HCO3- - OAA -> malate (uses NAPPH2) -> Pyruvate + NADPH2 + CO2

C3/ C4 comparison a) plenty of water, low temp C-3 higher quantum yield
CO2 compensation point
light compensation point shade/ high light intenety (often C4)

CAM day stomata closed

night stomata open CO2 uptake - PEP caboxylase - OAA - malate
starch-> triose P -> PEP + NADH,
malate -> vacuole (ATPase active) vacuole acidic maic acid accumulates