The unit pg stands for pictogram. It is one-trillionth of a gram. Because of the very small mass, it is expressed in the prefix form of the base units for convenience. Now, the mass of cofactor a is 41.5 pg per cell. Since there are a total of 105 cells, the total mass would be:
Total mass = 105 cells * 41.5 pg/cell = 4,357.5 pg