High School

Put the following compounds in order from the first made during the Calvin Cycle to the last:

a. 3PG
b. BPG
c. G3P
d. RuBP

Answer :

Final answer:

The Calvin cycle progresses through the compounds in the following order: RuBP is the starting point, followed by the conversion to 3PG, then to BPG (not explicitly listed but implied as a high-energy intermediate), and finally to G3P, which is partly used to regenerate RuBP.

Explanation:

The correct order of molecular conversions in the Calvin cycle starting from the first compound made to the last is:

  1. RuBP (Ribulose bisphosphate)
  2. 3PG (3-Phosphoglycerate)
  3. BPG (1,3-bisphosphoglycerate, also known as G3P in some texts, but not to be confused with glyceraldehyde-3-phosphate which is also abbreviated as G3P)
  4. G3P (Glyceraldehyde-3-phosphate)

During the Calvin cycle, carbon dioxide is fixed into a stable intermediate as it reacts with RuBP, catalyzed by the enzyme Rubisco. This first stable product is 3PG, which is then phosphorylated and reduced to G3P. A portion of the G3P molecules is used to regenerate RuBP, thus facilitating the continuation of the Calvin cycle.