Question

Which order of molecular conversions is correct for the Calvin cycle?

a. $\mathrm{RuBP}+\mathrm{G}3\mathrm{P}\to 3-\mathrm{PGA}\to \mathrm{sugar}$

b. $RuBisCO\to CO2\to \mathrm{RuBP}\to G3P$

c. $\mathrm{RuBP}+\mathrm{CO}2\to \left[\mathrm{RuBisCO}\right]3-\mathrm{PGA}\to \mathrm{G}3\mathrm{P}$

d.$\mathrm{CO}2\to 3-\mathrm{PGA}\to \mathrm{RuBP}\to \mathrm{G}3\mathrm{P}$

Short answer

The RuBisCO enzyme is regenerated throughout the Calvin cycle and has a strong affinity for CO2. As a result, option c.

$RuBP+CO2\to \left[RuBisCO\right]3-PGA\to G3P$is the correct solution.

Step-by-step solution

step-1: Intoducton

RuBP and CO2 mix in the Calvin cycle in the presence of the enzyme RuBisCO to produce 3-PGA, which is then transformed into G3P in the presence of the energy carriers ATP and NADPH.

step-2: Explanation of the correct answer

In the presence of the enzyme RuBisCO, RuBP and CO2 combine to produce 6 molecules of G3P. Only one molecule of G3P is converted to sugar, while the rest is recycled. As a result, option is the proper response (c).

step-3: Explanation of incorrect answer

Option (a) is incorrect because it occurs in the Calvin cycle in the wrong order. As a result, this is a bad choice.

Option (b) is incorrect because it occurs in the Calvin cycle in the wrong sequence. As a result, this is a bad choice.

Option (d)It does not occur in the Calvin cycle in the correct order of events. As a result, this is a bad choice.