meiosis

[pizza1994]

Under a microscope, a first and second polar body look alike. What stucture would distinguish them?

A bit confused on this one.....

Also, can someone tell me if in meiosis II at the end of it are there any sister chromatids ?

Thanks!

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[wizzed101]

eh... in order for the second polar to appear, the egg must have been fertilized. Soooo, I don't get under what circumstances would 2 of them can appear on the same microscope. That is a silly question. But the 1st one is diploid and the 2nd one is haploid.

There should not be any sister chromatid at the end of meiosis II unless a non-disjunction had taken place.

 

[pizza1994]

eh... in order for the second polar to appear, the egg must have been fertilized. Soooo, I don't get under what circumstances would 2 of them can appear on the same microscope. That is a silly question. But the 1st one is diploid and the 2nd one is haploid.

There should not be any sister chromatid at the end of meiosis II unless a non-disjunction had taken place.

both polar bodies are haploid I am pretty sure. And I don't think they have to appear on same microscope...question is just asking for differences between them

 

[wizzed101]

Sorry my bad. What I meant was that the first polar body will have twice as many genetic materials as the first, if no non-disjunction took place.Under normal condition (no aneuploidy), a dye can distinguish them. I am not sure if they can be differentiated by looking at the shape of the chromosomes because that would only be possible if the chromosomes were still condensed. That may be true for the first polar body, not sure about the second. But either way, again, only possible if no aneuploidy.

Secondly, because the second polar body can only be formed AFTER the egg is fertilized, when you collect them you should know exactly which is which. What I meant earlier was that I don't see the circumstance which you can collect two types of polar body at the same time. I read around a bit and learned about polar body biopsy, which I believe is a controlled procedure in vitro... so whoever performs it (correctly) should know exactly which polar body is under the microscope.

https://books.google.com/books?id=9...A#v=onepage&q="polar body biopsy 1987&f=false

If the question were to distinguish between 2 random polar bodies from different people, both of which are devoid of DNA, I don't believe it would be possible.

 

[pizza1994]

Sorry my bad. What I meant was that the first polar body will have twice as many genetic materials as the first, if no non-disjunction took place.Under normal condition (no aneuploidy), a dye can distinguish them. I am not sure if they can be differentiated by looking at the shape of the chromosomes because that would only be possible if the chromosomes were still condensed. That may be true for the first polar body, not sure about the second. But either way, again, only possible if no aneuploidy.

Secondly, because the second polar body can only be formed AFTER the egg is fertilized, when you collect them you should know exactly which is which. What I meant earlier was that I don't see the circumstance which you can collect two types of polar body at the same time. I read around a bit and learned about polar body biopsy, which I believe is a controlled procedure in vitro... so whoever performs it (correctly) should know exactly which polar body is under the microscope.

https://books.google.com/books?id=91R1CgAAQBAJ&pg=PA32&lpg=PA32&dq="polar+body+biopsy+1987&source=bl&ots=AQcJ35NEJC&sig=L7jhCiDKNSfSI8NC5GeVatugwQY&hl=en&sa=X&ved=0ahUKEwi-7abQusXJAhXE5YMKHXwUAW8Q6AEIHDAA#v=onepage&q="polar body biopsy 1987&f=false

If the question were to distinguish between 2 random polar bodies from different people, both of which are devoid of DNA, I don't believe it would be possible.

So I asked my old bio prof this and basically the answer is that polar body I is formed from meiosis I and so it has twice the amt of genetic material (homologous chromosomes) and polar body II which is formed from meiosis II will not (only have single chromosomes aka no sister chromatids).....and yeah you can prlly use a stain or something to check it out! thanks for the help!