List the sub-stages during Prophase I of meiosis, and describe the appearance/position of the chromosomes at each sub-stage.

Sub-stages during Prophase I of meiosis are: Leptotene; zygote; pachytene; diplotene and diakinesis.

Explanation:

In the sub-phase called leptotene, each chromosome is formed by two sister chromatids, where we can notice the presence of chronomers, which are small condensations.

Talking about the zygotene sub-phase, the chromossomes begin to pair up, and this process is called synapse.

The next sub-phase, called pachytene, each pair of homologous chromosomes has four chromatids, constituting one bivalent or tetrad, formed by sister chromatids and this is where the process called permutation or crossing-over occurs. Due to this process, we were able to visualize the chiasm under the microscope, which is nothing but an X cross.

The next sub-phase called diplotene, homologous chromosomes begin to drift apart but remain linked by regions where permutation occurred and in this sub-phase we can see the chiasm regions better than tha phase before.

In the last sub-phase called diakinesis, the condesation and separation of homologous chromosomes continue to happen With this, the chiasmas are sliding to the tips of the chromáids, a process called chiasma termination. As the phases evolve, the nucleolus and library disappear.