English: The C4 pathway contains a special structure in the leaves known as Kranz anatomy. There exists a layer of mesophyll cells that contain small chloroplasts encircling bundle sheath cells that have large chloroplasts necessary for the Calvin cycle.

A: Mesophyll Cell B: Chloroplast C: Vascular Tissue D: Bundle Sheath Cell E: Stroma F: Vascular Tissue: provides continuous source of water

1) Carbon is fixed to produce oxaloacetate by PEP carboxylase. 2) The four carbon molecule then exits the cell and enters the chloroplasts of bundle sheath cells. 3) It is then broken down releasing carbon dioxide and producing pyruvate. Carbon dioxide combines with ribulose bisphosphate and proceeds to the Calvin Cycle.

4) Pyruvate re-enters the mesophyll cell. It then reacts with ATP to produce the beginning compound of the C4 cycle.