Which event in the Calvin cycle would be the LEAST affected by a malfunction in the electron transport system?
A.
synthesis of G3P
B.
production of ADP
C.
regeneration of RuBP
D.
production of 3-PGA
To determine which event in the Calvin cycle would be the least affected by a malfunction in the electron transport system, let's first understand the roles of the electron transport system and the Calvin cycle.
The electron transport system, also known as the electron transport chain (ETC), is responsible for generating ATP through oxidative phosphorylation and transferring electrons to power chemical reactions in cells.
On the other hand, the Calvin cycle is a series of biochemical reactions that occur in the chloroplasts of plants during photosynthesis. It is responsible for converting carbon dioxide (CO2) into glucose, using the energy generated from ATP and NADPH produced by the light-dependent reactions.
Now, let's analyze the events of the Calvin cycle and their potential dependence on the electron transport system:
A. Synthesis of G3P (glyceraldehyde-3-phosphate):
G3P is a key intermediate molecule in the Calvin cycle, which is used to produce glucose and other sugars. The synthesis of G3P requires energy from ATP and reducing power in the form of NADPH, both of which are generated by the electron transport system. Therefore, a malfunction in the electron transport system would likely have a significant impact on the synthesis of G3P.
B. Production of ADP (adenosine diphosphate):
ADP is not directly involved in the Calvin cycle itself but is required for the regeneration of ATP. ATP is used as an energy source throughout various biochemical processes, including the synthesis of G3P. Since a malfunction in the electron transport system affects ATP production, it would indirectly impact the production of ADP.
C. Regeneration of RuBP (ribulose-1,5-bisphosphate):
Regeneration of RuBP is essential for the continuation of the Calvin cycle. RuBP is the molecule that captures carbon dioxide from the atmosphere, initiating the carbon fixation process. The regeneration of RuBP depends on ATP, which is generated by the electron transport system. Thus, a malfunction in the electron transport system would likely interfere with the regeneration of RuBP.
D. Production of 3-PGA (3-phosphoglycerate):
3-PGA is an intermediate molecule in the Calvin cycle, formed during the carbon fixation process. Although the production of 3-PGA requires ATP and NADPH, both of which are produced by the electron transport system, it is the initial product of the Calvin cycle and is not directly dependent on ATP or NADPH availability. Therefore, the production of 3-PGA would be the least affected by a malfunction in the electron transport system.
In conclusion, the correct answer is D. Production of 3-PGA would be the least affected by a malfunction in the electron transport system.