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April 29, 2024, 05:15:01 pm
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Author Topic: Chromosomes  (Read 1304 times)  Share 

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sayonara

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Chromosomes
« on: August 24, 2009, 05:16:06 pm »
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I should be studying evolution but anyway...

1. Do chromosomes normally exist as a single strand before replication?
2. The typical four-armed chromosome we're familiar with; are the two chromatids that make it up identical?
3. In somatic cells, are there 2 chromosomes for each number (1-22) in the nucleus?

Just need to confirm this information before moving on. Our class went through meiosis/mitosis way too fast, :S

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ed_saifa

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Re: Chromosomes
« Reply #1 on: August 24, 2009, 05:46:39 pm »
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1. They exist as chromatin and remains as chromatin after duplication; in prophase the chromatin starts to condense into discrete chromosomes

2. The sister chromatids are identical

3. Yes from the sperm and egg; 46 total including the sex chromosomes
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sayonara

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Re: Chromosomes
« Reply #2 on: August 24, 2009, 06:00:19 pm »
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Thanks for the response, but what do you mean by "from the sperm and egg"?
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ed_saifa

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Re: Chromosomes
« Reply #3 on: August 24, 2009, 06:10:17 pm »
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Sperm and egg are both haploid(23 chromosomes) and together they form a diploid(46).
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(\ /)
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"It's not a community effort"
"It's not allowed. Only death is a valid excuse"
"Probably for the first time time this year I was totally flabbergasted by some of the 'absolute junk' I had to correct .... I was going to use 'crap' but that was too kind a word"
"How can you expect to do well when
-you draw a lemon as having two half-cells connected with a salt bridge
-your lemons come with Cu2+ ions built in" - Dwyer
"Why'd you score so bad?!" - Zotos
"Your arguments are seri

sayonara

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Re: Chromosomes
« Reply #4 on: August 24, 2009, 06:25:35 pm »
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Thanks!
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TrueLight

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Re: Chromosomes
« Reply #5 on: August 24, 2009, 06:55:36 pm »
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yeah chromosomes are highly supercoiled around proteins (double stranded DNA still) and need to unwind before they can replicate.

humans have 23 pairs of chromosomes in somatic cells
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