Calvin Cycle and RuBP Regeneration

Vocabulary flashcards detailing the steps, intermediates, and energy requirements of the Calvin cycle, including carbon fixation, reduction, and the regeneration of RuBP.

Phase 3

The phase of the cycle in which $5\text{ G3P}$ are used to regenerate $3\text{ RuBP}$ ($\text{the CO}_2\text{ acceptor}$) by spending $3\text{ ATP}$.

RuBP

The five-carbon $\text{CO}_2$ acceptor molecule that combines with carbon dioxide during carbon fixation and is reformed during Phase 3 of the cycle.

Rubisco

The enzyme that catalyzes the initial carbon fixation reaction by combining $3\text{ CO}_2$ with RuBP to yield an unstable six-carbon intermediate.

Carbon Fixation

The initial phase of the cycle wherein $3\text{ CO}_2$ enter and are fixed by Rubisco into an unstable intermediate that splits into 6 molecules of 3-phosphoglycerate.

3-Phosphoglycerate

A three-carbon intermediate produced from the cleavage of the unstable six-carbon intermediate during carbon fixation, which is subsequently phosphorylated by $6\text{ ATP}$.

1,3-Bisphosphoglycerate

The phosphorylated intermediate formed when 6 molecules of 3-phosphoglycerate receive phosphate groups from $6\text{ ATP}$ before being reduced.

Reduction Phase

The stage of the cycle in which 6 molecules of 1,3-bisphosphoglycerate are reduced by $6\text{ NADPH}$ (yielding $6\text{ NADP}^+$ and $6\text{ P}_i$) to produce 6 molecules of G3P.

G3P

The three-carbon sugar product of the reduction phase, of which $1\text{ blank}$ exits the cycle as net sugar output and $5Blank$ are recycled to regenerate RuBP.