1. Sedoheptulose 1,7-bisphosphate is an intermediate in the Calvin cycle but not in the pentose phosphate pathway. What is the enzymatic basis of this difference?
2. . An illuminated suspension of Chlorella is actively carrying out photosynthesis. Suppose that the light is suddenly switched off. How would the levels of 3-phosphoglycerate and ribulose 1,5-bisphosphate change in the next minute?
3. An illuminated suspension of Chlorella is actively carrying out photosynthesis in the presence of 1% CO2. The concentration of CO2 is abruptly reduced to 0.003%. What effect would this reduction have on the levels of 3-phosphoglycerate and ribulose 1,5-bisphosphate in the next minute?
4. 2-Carboxyarabinitol 1,5-bisphosphate (CABP) has been useful in studies of rubisco.
(a) Write the structural formula of CABP.
(b) Which catalytic intermediate does it resemble?
(c) Predict the effect of CABP on rubisco.