Final answer:
The main enzyme that 'fixes' carbon dioxide in the process of photosynthesis during the Calvin cycle is called RuBisCO. This enzyme is crucial for converting inorganic carbon from CO₂ into an organic form that plants can use for energy and growth, and it serves as the starting point for the synthesis of glucose.
Step-by-step explanation:
The major enzyme responsible for 'fixing' carbon dioxide during the Calvin cycle in plants is RuBisCO, which stands for ribulose-1,5-bisphosphate carboxylase/oxygenase. RuBisCO facilitates the first major step in the process by catalyzing the addition of carbon dioxide to ribulose bisphosphate (RuBP), leading to the production of 3-phosphoglycerate (3-PGA). This initial step is crucial as it incorporates the inorganic carbon from CO₂ into an organic molecule which can then be used in the biosynthesis of glucose and other carbohydrates vital for the plant's energy and structural needs.
Plants have evolved different pathways for carbon fixation, with the C3 pathway being the most common, where RuBisCO catalyzes the reaction of CO₂ with RuBP. C4 plants have adapted to fix CO₂ in a separate compartment initially, leading to improved efficiency under certain conditions.
As one of the most abundant enzymes on earth, RuBisCO plays a significant role in the global carbon cycle, making it a cornerstone of photosynthesis and a key element in the fight against climate change by removing CO₂ from the atmosphere.