Genetics Question: Meiosis Questions

[emminent]

Does variation occur only for anaphase I since anaphase II is pretty much similar to anaphase of mitosis correct?

Another thing is can someone post on keep tracking of #'s of chromosomes throughout the phases both mitosis and meiosis? I'll start; just correct me if I'm wrong.

Mitosis
Prophase: beginning all start with 46 chromosomes/92 chromatids (Mitosis and Meiosis)
Metaphase: 46 chromosomes/92 chromatids
Anaphase: 92 chromosomes/92 chromatids
Telophase: 46 chromosomes/46 chromatids each daughter cell


Meiosis
Prophase I: beginning all start with 46 chromosomes/92 chromatids (Mitosis and Meiosis)
Metaphase I: 46 chromosomes/92 chromatids
Anaphase I: 23 chromosomes/46 chromatids
Telephase I: 23 chromosomes/46chromatids each daughter cell?

Prophase II: 23 chromosomes/46 chromatids
Metaphase II: 23 chromosomes/46 chromatids
Anaphase II: 23 chromosomes/46 chromatids
Telophase II: 23 chromosomes/23 chromatids for each daughter cell x4

I'm pretty sure I messed up a fair amount lol...

---

Members don't see this ad.

 

[emminent]

Bump

 

[djwon1]

I think there are 92 chromatids at anaphase 1
23 chromosomes at prophase 1 (after crossing over) <-- not sure if 1 tetrad is considered as 1 chromosome. if it isn't, then 23 homologous pairs.
Same for metaphase 1
46 chromosomes at anaphase 1 (92 chromatids)
23 chromosomes at telophase 1 (46 chromatids) x 2 daughter cells

46 chromosomes at anaphase 2 (46 chromatids)
23 chromosomes at telophase 2 (23 chromatids) x 4 daughter cells

At anaphase, you are doubling chromosome #.

please correct me if i'm wrong !

 

[Tmoneymaj]

Great question!! unfortunately I'm wondering if those are correct also.

 

[emminent]

Yeah hope someone can confirm these posts cause I'm sure knowing chromosome/chromatid #'s are high yield questions. Always get me confused. I checked AP cliff but still confused.

 

[emminent]

Bump

 

[Kittenz]

+1

 

[Project Pat]

Genetic variation occurs from 3 events:

1. Crossing over - during prophase I
2. Independent assortment of homologues - during metaphase I
3. Random joining of gametes - fertilization is union of egg and sperm.

 

[DocBella]

How man chromosomes are present in the secondary spermatocytes arrested in metaphase of meiosis II?
23 or 46?

I thought it was 46, bc it says arrested, meaning they haven't split yet, they're still at the metaphase plate, but the correct answer is 23. Can anyone please explain why?

2n
2n
1n 1n
1n 1n 1n 1n


Thank!~~

 

[TheEpicFruitCake]

How man chromosomes are present in the secondary spermatocytes arrested in metaphase of meiosis II?
23 or 46?

I thought it was 46, bc it says arrested, meaning they haven't split yet, they're still at the metaphase plate, but the correct answer is 23. Can anyone please explain why?

2n
2n
1n 1n
1n 1n 1n 1n


Thank!~~

By your logic the answer would be 23

 

[emminent]

How man chromosomes are present in the secondary spermatocytes arrested in metaphase of meiosis II?
23 or 46?

I thought it was 46, bc it says arrested, meaning they haven't split yet, they're still at the metaphase plate, but the correct answer is 23. Can anyone please explain why?

2n
2n
1n 1n
1n 1n 1n 1n


Thank!~~

Arrested probably confused you just ignore that and think instead "how many chromosomes are present at that time during metaphase." There are 23 chromosomes but 46 chromatids at prophase and metaphase II and like you said they "haven't split" yet. At anaphase II those chromosomes split to produce four haploid cells each 23 chromosomes.

 

[DocBella]

Arrested probably confused you just ignore that and think instead "how many chromosomes are present at that time during metaphase." There are 23 chromosomes but 46 chromatids at prophase and metaphase II and like you said they "haven't split" yet. At anaphase II those chromosomes split to produce four haploid cells each 23 chromosomes.

Thanks! that helped clarify it 🙂

 

[DocBella]

By your logic the answer would be 23

lol do u wanna elaborate? If my logic made sense to me, I wouldn't have asked! haha

 

[TheEpicFruitCake]

lol do u wanna elaborate? If my logic made sense to me, I wouldn't have asked! haha

You have 23 chromosomes when meiosis II begins. If they haven't split, the number is still 23

 

[emminent]

Thanks! that helped clarify it 🙂

I'd also like to remind/advise you that when you see poorly worded or confusing questions, remember to think of the bigger picture and see what they really want to ask you. Once I saw arrested I think "ignore that cause I'll be overthinking" and proceed to read whole question. Then I'll think "oh so they want to know how many chromosome at metaphase II." I don't even have to worry about secondary spermatocyte or even if it said secondary oocyte b/c they both engage in the same basic process of meiosis (except meiosis for eggs cells results in polar bodies and 1 single egg). Main indicator was "metaphase/meiosis II."

I just took the DAT and there were some crappy worded questions so keep that in mind.

 

[DocBella]

You have 23 chromosomes when meiosis II begins. If they haven't split, the number is still 23

Yep, I see it now, thanks! I think the term "arrested" threw me off and then I pictured the homologous chromatids as a diploid, it didn't process that their ploidy hasn't changed.

 

[DocBella]

I'd also like to remind/advise you that when you see poorly worded or confusing questions, remember to think of the bigger picture and see what they really want to ask you. Once I saw arrested I think "ignore that cause I'll be overthinking" and proceed to read whole question. Then I'll think "oh so they want to know how many chromosome at metaphase II." I don't even have to worry about secondary spermatocyte or even if it said secondary oocyte b/c they engage in similar processes. Main indicator was "metaphase/meiosis II."

I just took the DAT and there were some crappy worded questions so keep that in mind.

Thats great advise! thanks so much!! 😀

 

[TheEpicFruitCake]

Does variation occur only for anaphase I since anaphase II is pretty much similar to anaphase of mitosis correct?

Another thing is can someone post on keep tracking of #'s of chromosomes throughout the phases both mitosis and meiosis? I'll start; just correct me if I'm wrong.

Mitosis
Prophase: beginning all start with 46 chromosomes/92 chromatids (Mitosis and Meiosis)
Metaphase: 46 chromosomes/92 chromatids
Anaphase: 92 chromosomes/92 chromatids
Telophase: 46 chromosomes/46 chromatids each daughter cell


Meiosis
Prophase I: beginning all start with 46 chromosomes/92 chromatids (Mitosis and Meiosis)
Metaphase I: 46 chromosomes/92 chromatids
Anaphase I: 46 chromosomes/92 chromatids (The cell hasn't split yet, the chromosomes just move to the poles)
Telephase I: 23 chromosomes/46 chromatids (The cell is split at the end of Telephase so X2 for each daughter cell)

Prophase II: 23 chromosomes/46 chromatids (Just looking at 1 daughter cell, remember there are actually 2 after meiosis 1)
Metaphase II: 23 chromosomes/46 chromatids
Anaphase II: 46 chromosomes/46 chromatids (Cell not split yet)
Telophase II: 23 chromosomes/23 chromatids for each daughter cell x4

Remember, to count chromosomes, count kinetochores. Its really dumb I know. Look at Mitosis. At the beginning of Anaphase (before the split) you will have 46 chromosomes, after you split you have 92, but the same number of chromatids. So before the split its called a chromosome and after the split its still called a chromosome, lols