X chromosome "weight"? According to Wikipedia, the X chromosome has approximately 153 million base pairs, while the Y chromosome has only 60 million base pairs. Thus, the difference is roughly 93 million base pairs. My question is: Could this "extra" 93 million base pairs in virtually every single female cell of the human body slightly contribute to the "extra" relative weight of the female as a whole, in comparison to a male (of course) with a similar amount of cells? Or would this weight be so small that we can consider it negligible?

Theoretically...

`93 million bp/cell x 650 daltons/bp x 10^13 cells/body x 1.66 * 10^-27 kg/dalton = 0.001 kg`

So I would say it's not too much of a difference :P

however this ignores the rest of the chromosomal material: histones