Ploidy for Anaphase I

[Silverfalcon]

---

Members don't see this ad.

This is from Kaplan Biology Book (new one with Scientific American). I'm not sure if I agree with the answer... So, I would appreciate any explanation. Thank you.

Question reads: "During which phase of the meiotic cycle does the cell have a diploid number of chromosomes?"
A) In the beginning of prophase I
B) At the end of anaphase I
C) At the end of telophase II
D) Both A and B

The solution says that it's D. I don't get why B is valid though. Like, I know that it is still a single cell at the end of anaphse, but the homologous chromosomes have split into two opposite ends. So, doesn't that mean each end is haploid? Also, the solution said that the ploidy does not change until after telophase I. But, don't the cells separated into two by then, each with haploid as ploidy?

Ugh.

 

[Phantastic]

The two daughter cells that emerge from Meiosis I will each have a tetrad of two identical sister chromatids (unless crossing over occurred) for each chromosome. You're right that the daughter cells are haploid. The cell is still diploid in anaphase I because, as you said, it's still in the same cell, even though they are pulled apart and will divide soon.

I would just associate diploid w meiosis I, and haploid with meiosis II.

e.g.
Primary spermatocytes (Diploid) undergo Meiosis I to form two Secondary spermatocytes (haploid) which then each undergo Meiosis II. While the cell is in anaphase I, it is still just a primary spermatocyte, and will therefore still be diploid.

Hope that helps.

 

[Silverfalcon]

I would just associate diploid w meiosis I, and haploid with meiosis II.

This works for me. 🙂 Thank you.

 

[docelh]

After meiosis I, the two daughter cells are considered haploids because the chromosomes are not homolog pairs.

The reason B is correct is because cytokinesis hasn't happened yet, so the duplicated homologs are still in one cell technically.