Confusiosomes

[2810712]

I get confused often due to this. please help me out.
Sometimes chromosemes have four arms while sometimes they have 2 , [ this depends on the cell phase] so does the definition of chromatid change accordingly? ? ?

Also tetrad and diad also confuse me teaming with the words ' chromosome and chromatid' , please help...
Also , how many DNAs does a chromosome contain ? ? ?

thanks,

hrushikesh

[cytochromeP]

As in during 'metaphase' of mitosis in somatic cells (i.e. normal body cells i.e. non-germinal cells)
1 Chromosome = 2 Chromatids
1Chromatid = 2 Arms
1 Chromosome = 4 Arms
1 Chromatid = 1 DNA strand (2nd Chromatid is the copy of the 1st)
1 Chromosome = 2 (identical) DNA strands

I hope that now Chromosomes are NOT = Confusiosomes !

Correct me if I am wrong.
Hope this helps.

[2810712]

Thanks ,
In metaphase's diagram of mitosis four armed uinits are shown to be attached to the aster-fibres then they are shown to get separated into 2 two armed units . I think these 2-armed units should also be called as chromosomes as cells have chromosomes . So
there doesn't seem single definition of chromosomes . The metaphasic chromosomes are 4 armed and ana and telo and inter phasic chromosomes are 2 armed !!!
Probably , i've misconceptions here. soplease turn my confusiosomes to chromosomes...


U'r way of answering really helped me, thanks again.
hrushikesh

[cytochromeP]

Yes, the definition of a chromosome does vary with the stage in the cell cycle.
The structures during metaphase of mitosis which u refer to as "2 armed units" are called "sister chromatids". And this this complex of 2 sister chromatids (4 -armed unit) is called a chromosome since (very important) - there is only one centromere.
Yes, the ana, telo phase chromosome is indeed 2-armed. BUT in interphase there is no such thing as a well defined chromosome (and hence no arms...)!

I must thank you too since it was becoz of ur query that i revisited my 'basics' - checked out my text-book, googled around... and now my mind is refreshed on this topic [/u]