C4 Plants

  C4 plants live in hot, dry places and have adapted to one of rubisco's inefficiencies.

They use 12 ATP per glucose.

                                 

C4 metabolism involves two different cell types:
     The mesophyll cell and the bundle sheath cell.
        C4 metabolism moves the Calvin Benson cycle away from the "air outside".
This way, oxygen doesn't inhibit the Calvin Benson cycle.

  

What's Rubisco's problem, anyway?

#1:  It's slow.  So, you need lots of it.
            #2:  Oxygenase.  (5C)RUBP + O2         (3C)3PG and (2C) compound

The 2C compound cannot enter the cycle right away. 
It has to be broken down to CO2 first. 
Valuable "fixed carbon" is broken down to CO2. 
This undoes the normal work of the Calvin Benson cycle.

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