Prophase 1 and 2 occur in which is the process of creating haploid cells.
In prophase 1 there are two copies of each chromosome and the cell is said to be diploid (one copy from mum and one copy from dad). The two copies of each chromosome come into contact with each other and swap parts of the chromosome. This introduces genetic diversity.
However during metaphase 1 the pairs of chromosomes are separated – one going into one cell and the other going into another. This means that there are no longer two copies of the same chromosome and therefore crossing over cannot take place.
So in summary prophase 1 contains crossing over but prophase 2 does not.
