- Anonymous1 decade agoFavorite Answer
Also called the Calvin Cycle:-
The second stage of photosynthesis, which takes place in the stroma of the chloroplast, can occur without the presence of sunlight. In this stage, known as the Calvin Cycle, carbon molecules from CO2 are fixed into glucose (C6H12O2). The reactions of the Calvin Cycle is as follows:
1. A five-carbon sugar molecule called ribulose bisphosphate, or RuBP, is the acceptor that binds CO2 dissolved in the stroma. This process, called CO2 fixation, is catalyzed by the enzyme RuBP carboxylase, forming an unstable six-carbon molecule. This molecule quickly breaks down to give two molecules of the three-carbon 3-phosphoglycerate (3PG), also called phosphoglyceric acid (PGA).
2. The two 3PG molecules are converted into glyceraldehyde 3-phosphate (G3P, a.k.a. phosphoglyceraldehyde, PGAL) molecules, a three-carbon sugar phosphate, by adding a high-energy phosphate group from ATP, then breaking the phosphate bond and adding hydrogen from NADPH + H+.
3. Three turns of the cycle, using three molecules of CO2, produces six molecules of G3P. However, only one of the six molecules exits the cycle as an output, while the remaining five enter a complex process that regenerates more RuBP to continue the cycle. Two molecules of G3P, produced by a total of six turns of the cycle, combine to form one molecule of glucose
- 5 years ago
Calvin cycle takes place in stroma of a chloroplast, can occur without the presence of sunlight, Carbon from CO2 fixed into glucose.
1. 5 carbon sugar molecule called RuBP acceptor binds CO2 in stroma. It is CO2 fixation catalyzed by RuBP. Carboxylase, an unstable 6 carbon sugar molecule breaks into 2 3-carbon sugar- 3pg called phosphoglyceric acid (PGA).
2. 2 3PG molecules convert to g3P, a 3-carbon sugar, and adds high energy phosphate group form ATP, then breaks bond adding H to form NADPH + H.
3. After 3 turns of the cycle, using 3 molecules of CO2, produces 6 molecules of G3P, however only one of the six enters as an output,while the remaining 5 form/enter a complex process that regenerates more RuBP to continue the cycle . Two molecules of G3P, produced by six turns of the cycle combine to form one molecule of glucose.
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- 1 decade ago
BIOsynthetic phase(2nd phase) of photosynthesis is called calvin benson-bassum cycle.. cause they discovered different phases of this cycle.
- 4 years ago
18 ATP, 12 NADPH, and CO2 makes glucose.