ATP requirement for Glucose Synthesis via C4 Pathway

C4 pathway is a type of photosynthesis that is adapted to arid and hot environments. In this pathway, carbon dioxide is first fixed into a four-carbon compound, oxaloacetate, which is then transported to the bundle-sheath cells where it is further metabolized to produce glucose. The process requires a significant amount of ATP, and the correct answer to the question is A) 30 ATP.

ATP Requirement for the C4 Pathway

The C4 pathway is an energy-intensive process, and it requires a large amount of ATP to synthesize one molecule of glucose. The following are the steps involved in the C4 pathway and the ATP requirement for each step.

1. Carbon Dioxide Fixation

The first step in the C4 pathway is the fixation of carbon dioxide into a four-carbon compound, oxaloacetate. This process requires the enzyme phosphoenolpyruvate carboxylase (PEPCase) and two molecules of ATP.

2. Transport of Oxaloacetate

The oxaloacetate is then transported to the bundle-sheath cells, where it is further metabolized to produce glucose. The transport of oxaloacetate requires the enzyme malate dehydrogenase and one molecule of ATP.

3. Decarboxylation

In the bundle-sheath cells, the oxaloacetate is decarboxylated to release carbon dioxide and produce pyruvate. This process requires the enzyme pyruvate phosphate dikinase and two molecules of ATP.

4. Regeneration of Phosphoenolpyruvate

The pyruvate is then transported back to the mesophyll cells, where it is converted into phosphoenolpyruvate (PEP) through a series of enzymatic reactions. This process requires the enzyme pyruvate kinase and four molecules of ATP.

5. Glucose Synthesis

Finally, the PEP is used to synthesize glucose through the process of gluconeogenesis. This process requires the enzyme fructose-1,6-bisphosphatase and 21 molecules of ATP.

Total ATP Requirement

Adding up the ATP requirement for each step, we get a total of 30 ATP molecules required to synthesize one molecule of glucose via the C4 pathway.

Conclusion

The C4 pathway is an energy-intensive process that requires a large amount of ATP to synthesize one molecule of glucose. The correct answer to the question is A) 30 ATP.