Author Topic: BIOLOGY CONFUSED?????  (Read 887 times)

Offline cashem'up

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BIOLOGY CONFUSED?????
« on: May 05, 2010, 03:47:38 pm »
are chromosomes double structured or single structured in a specialized cell? As in usually are chromosomes double structured or do they only become in requirement for mitosis??

please help thanx been buggin me for a long time

Offline tmisterr

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Re: BIOLOGY CONFUSED?????
« Reply #1 on: May 05, 2010, 03:56:08 pm »
yes, chromosomes are double structured, they are 2 sister chromatids connected at a centromere each containing an identical D.N.A strand. During anaphase, the choromosome seperated into two chromatids, one will go to each cell. it will remain like this, as a single structure called chromatin until the next division, when the D.N.A replicates forming two strands, each strand making a chromatid and the two joined strands making a chromosome

nid404

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Re: BIOLOGY CONFUSED?????
« Reply #2 on: May 05, 2010, 04:04:03 pm »
confusion confusion  ;D :P

I'm high :P

anyway, I'll clear your doubt..

chromatin = uncondensed state of chromosome, single stranded (1 DNA molecule)  
chromosome= referred to chromosome as it condenses and becomes visible under the light microscope. ( It has 2 DNA molecules after interphase...since it has replicated)
chromatids= each of the 2 DNA strands on the chromosome are referred to as sister chromatids

so in a somatic cell...human somatic cell that is
there are 46 uncondensed chromosomes(chromatin)-->46 DNA strands
During mitosis, this number doubles, theres are 92 chromosomes--->92 DNA strands ( 2 strands attached by a centromere)
During anaphase, the 2 strands move to opp poles.
The new cells now have the original 46 chromosomes

I hope this is clear...

Offline cashem'up

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Re: BIOLOGY CONFUSED?????
« Reply #3 on: May 05, 2010, 05:40:10 pm »
confusion confusion  ;D :P

I'm high :P

anyway, I'll clear your doubt..

chromatin = uncondensed state of chromosome, single stranded (1 DNA molecule)  
chromosome= referred to chromosome as it condenses and becomes visible under the light microscope. ( It has 2 DNA molecules after interphase...since it has replicated)
chromatids= each of the 2 DNA strands on the chromosome are referred to as sister chromatids

so in a somatic cell...human somatic cell that is
there are 46 uncondensed chromosomes(chromatin)-->46 DNA strands
During mitosis, this number doubles, theres are 92 chromosomes--->92 DNA strands ( 2 strands attached by a centromere)
During anaphase, the 2 strands move to opp poles.
The new cells now have the original 46 chromosomes

I hope this is clear...

ok so out of these 46 chromatins that we have  are in pairs rite........ and then wouldnt a homologous pair have 4 chromatins in total , as in 2 chromosomes with a pair of sister chromatids each  and then thus since there are 23 pairs wouldnt it make 92.......or  are they considered in pairs only when they are condensed......
thanks