Page 13 - LN-PHOTOSYNTHESIS IN PLANTS

Hence, the fixation of 6 molecules of CO 2 and 6 turns of the cycle are required in
order to release one molecule of glucose from the pathway.

3. Regeneration
For the continuous and uninterrupted functioning of the Calvin cycle, there must be a
regular supply of ATP, NADPH and also sufficient amount of RuBP is required. The
regeneration of RuBP (CO 2 acceptor) is a complex process and involves many types
of sugar starting from triose (3C) to heptose (7C).
The regeneration step require one ATP molecule for phosphorylation. Hence, for
every CO 2 molecule that- enters the Calvin cycle, required are 3 molecules of ATP
and 2 molecules of NADPH.
The cyclic phosphorylation takes place in order to meet the difference in the number
of ATP and NADPH used in the dark reaction.
Thus, in order to produce one molecule of glucose through the Calvin pathway, 18
ATPs and 12 NADPHs are required.
This can he easily understood by the following table given below