At what stage of mitosis does the amount of genetic material in each chromosome become half of what it just was?

Cell division is when the genetic material in each chromosome splits off and becomes half of what it was.

Cell division is where this happens.

Hope this helps.

this protocol provides a detailed procedure for co-immunoprecipitation (co-ip) to identify protein–protein interactions.

not sure if this what   you'r looking for would be percent composition