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Meiosis/Mitosis questions

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Meiosis/Mitosis questions

Postby take_no_prisoners » Sat Apr 07, 2007 5:25 am

Hi guys, these are just basic true false questions. I've written in brackets what I think the answer is...

1. Homologous chromosomes pair in meiosis but not mitosis.
(I think True)

2. Following both mitosis and the first division of meiosis, each of the daughter cells produced have the same number of chromosomes in the parent cell.
(I think True)

3. DNA replication occurs during both mitosis and meiosis.
(I think false. It occurs before mit/mei in interphase?)

4. Chiasma formation occurs during meiosis but not mitosis
(True)

5. In both mitosis and meiosis, chromosomes are at their most compacted at metaphase.
(True)

Am I right? Please correct me if you think I'm wrong!

Thanks!
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Postby amolvaidya06 » Sat Apr 07, 2007 9:31 am

Not sure, but I think number two should be false. My understanding is that after the first division in meiosis, the sister chromatids are still jioned, and therefore still considered one chromosome.
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Postby Darby » Sat Apr 07, 2007 6:27 pm

2. You're wrong, the answer above is right.

3. It depends on if they really mean "during," in which case you're right. If they really mean "leading into," then, not so much.

4 looks okay, and I'm not sure about 5 - it seems like a bad thing to generalize over, anyway.
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Postby take_no_prisoners » Sun Apr 08, 2007 4:11 am

Darby wrote:2. You're wrong, the answer above is right.

3. It depends on if they really mean "during," in which case you're right. If they really mean "leading into," then, not so much.

4 looks okay, and I'm not sure about 5 - it seems like a bad thing to generalize over, anyway.


Thanks. I think two must be wrong then. In 3 I'm pretty sure they mean
during" so that's OK.

As for 5, I wouldn't be going into too much detail, so I'm pretty sure they are making a general statement.
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Postby LLCOOL » Mon Apr 09, 2007 12:23 am

True,because in meiosis the homologus pair up before separating forming two haploid cells[/i]
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Postby LLCOOL » Mon Apr 09, 2007 12:35 am

Q2.False reason being is that ,in meiosis the sister chromatids separate and each cell divides againand are unduplicated and on the other hand the mitosis sister chromatids separate and the cell divides into two diploid daughter cell
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Postby take_no_prisoners » Mon Apr 09, 2007 1:41 am

Thanks for clearing that up. :D
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Postby take_no_prisoners » Mon Apr 09, 2007 4:38 am

I've just got one more question:

the following question relates to a human cell undergoing meosis.
(i) In a human male the X and Y chromosomes are not homologous and yet the gametes always contain either one or the other of these chromosomes, but not both nor neither. Why?

I really don't know how to explain it...
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Postby mith » Mon Apr 09, 2007 5:01 am

check out how sperm is made.
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Postby take_no_prisoners » Mon Apr 09, 2007 5:23 am

mith wrote:check out how sperm is made.


I understand that a single sperm cell carries 22+either an X or a Y which hence determines the sex of the child, but I'm not sure about the whole splitting process so that only 1 of either the X or the Y is contained in the sperm.
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Postby mith » Mon Apr 09, 2007 2:03 pm

keyword "spermatogenesis" do a forum search dr stein has posted quite a few pics.
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