IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: cashem'up on May 05, 2010, 03:47:38 pm
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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
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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
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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...
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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