the elemental ratio is approximately
C106: H263: O110: N16: P1: S0.7
Cells are approximately 70% water => 30% of weight is in this ratio
If you treat the above ratio as the "stoichiometry" of a cell
106 * 12
263 * 1
110 * 16
16 * 14
1 * 32
0.7 * 50
_______
3586
and the porportion of carbon would be 1272/3586 = 35%
this means that C is 35% of the weight of the dry weight