Describe what is occurring in each of the following prases of meiosis including the number of chromatid arms?

Question

Describe what is occurring in each of the following phases of meiosis including the number of chromatid arms present in each cell in each phase if the 2N number is 16.?
Prophase 1
Telophase 1
Metaphase 2
Anaphase 2

* I know what happens during each of these phases, but I am unclear about the number of chromatid arms present in each cell in each phase if the 2N number is 16.

If someone could explain precisely how to calculate or figure this out, that would help me greatly, thank you.

Answer 1

If we consider a double-stranded chromosome to have two chromatid "arms", then we only have to know when the homologous chromosomes pull away from each other (anaphase I) and when the double-stranded chromosomes split at the centromeres and the sister chromatids go to opposite poles (anaphase II).

So, if the 2n number is 16, and the chromosomes are double-stranded in the beginning of meiosis (since the DNA was copied during the S stage of interphase), then there are 32 chromatids at the beginning of meiosis.

Prophase 1 -- 32

Telophase 1 -- 16 because the homologous pairs have separated, so there are only 8 double-stranded chromosomes in each nuclear area

Metaphase 2 -- still 16 because the chromosomes are still double-stranded and are just lined up on the equator of the spindle

Anaphase 2 -- 8 because the 8 double-stranded chromosomes have split at their centromeres and the sister chromatids have been pulled away from each other