Quit 6 Flashcards
Catabolism
oxidative and produces atp
Anabolic
reductive NAD(P)H required, burn atp
Chloroplasts
carbon assimilation
Amyloplasts
Starch granule storage
Proplastids
Loss of internal membranes and chlorophyll
Three Stages of Carbon Assimilation
Fixation: Ribulose 1-5-bisphosphate +CO2
Reduction: 3-phosphoglycerate, ATP, NADPH
Regeneration of Acceptor: Glyceraldehyde 3-phosphate, ATP
step 1 Rubisco
Ribulose 1,5 bisphosphate carboxylase/oxygenase
First Committed step in Calvin cycle
Irreversible.
Activated by high pH and Magnesium (z scheme is working)
C3 plants
First product of CO2 is 3-phosphoglycerate
Step 2-3
Phosphoglycerate to gylceraldehyde-3-phosphate.
Like gluconeogenesis but requires nadph
Glyceraldehyde-3-phosphate can be converted into dihydroxyacetone phosphate
Dihydroxyacetone
Enzyme: triose phosphare isomerase (Glucose,sucrose,starch synthesis)
Can be converted back to Ribulose 1,5-bisposphate
Step 3
Regeneration Ribulose-1,5- Bis-phosphate from triose phosphates
Transaldolases rxn 1&4
Transketolase rxn 3&6
What Drives Calvin Cycle
Last step ATP hydrolysis of
ribulose 5 phosphate to ribulose 1,5 bisphosphate
net rxn to make Hexose
6CO2 +18ATP + 12 NADPH –> C6H12O6 +18 ADP + 12 NADP+
Fructose 1,6 Bisphosphotase
Activated by rise in pH and Mg2+ (Sun)
Committed step > Calvin Cycle
Proton gradient
light activated H+ flows into thylakoid lumen and mg2+ leaves. pH of stroma increase activating Calvin cycle
Carb Biosynthesis
Synthesis of sugars from CO2 and ATP/NADPH
phosphorus-trioses must be exported from stroma of chloroplast into cytosol before made into hexoses.
Pi-Triose phosphate antiporter
Cytosol > Stroma : free phosphate
Stroma > Cytosol : Dihydroxyacetone phosphate (from Calvin cycle) ==>==>==> sucrose
And
Cyt > Str : 3 phosphorusgylcerate
Str > Cyt : Pi
ferrodoxin-thiodoxin reductase
Thioredoxin s-s (inactive) + Ferrodoxin(red) –> thioredoxin sh sh (active) + Ferrodoxin (ox)==>==> +O2 -> 1/2 H2O
Ferrodoxin reduced comes from ETC
make starch/sucrose or eat at night
Thioredoxin pathway
Ribulose-1,5-Bis Phosphate Carboxylase/Oxygenase
Rubisco + High [O2] -> Phosphoglycolate + 3-Phosphoglycerate
Cyanobacteria
Carboxysome (impermeable membrane co2 and o2 can’t enter) HCO3 can enter.
Glycolate Pathway
plant makes use of the products to make 2-phosphoglycolate to serine + CO2
C-3 vs C-4 plants