Question

In what phase does DNA coil up and chromosomes become visible while the nuclear membrane is breaking down?

Answer 1

Prophase is the phase when this occurs

Answer 2

This is the Prophase. 

1) The chromosomes coil up and become visible while the nuclear envelope disappears. 
2) Sister chromatids are appears.
3) A centriole forms at each pole and spindle fibers made of microtubules grow out of it.
4) Short microtubules stick out from the centriole in a star shape known as an aster.

I don't remember liking biology but I do remember some things from it.