Question

What is RuBisCo? Explain its role in $C_3$ and $C_4$ photosynthesis.

Answer 1

$C_3$ and $C_4$ plants have Ribulose 1, 5- bisphosphate carboxylase/oxygenase (RuBisCO) enzyme present in the mesophyll cells of the leaves. It is a key enzyme which catalyzes carboxylation reaction during photosynthesis. It is the most abundant protein on earth.

In $C_3$ plants it occurs in the mesophyll cells. It causes photorespiration. In $C_4$ plants, it occurs in the bundle sheath cells. Instead of RuBisCO, they have another enzyme called phosphoenolpyruvate carboxylase (PEP carboxylase).