[PW] ? DNA question

[Peter Macinnis]

John Franklin wrote:

> (For those who haven't picked it up from this thread, let alone other  
> sources, the X and Y chromosomes get their names from their shapes;  
> the "X" shape is the normal one for a chromosome, but the Y is missing  
> a leg...)

I don't think that is right, John.  See the human karyotype at 
http://homepage.mac.com/wildlifeweb/cyto/human/HSA550.gif

I suspect (but do not assert) that the XY convention was first applied 
in _Drosophila melanogaster_, the Columbia fly-room fruit fly, but its 
karyotype does not show that shaping either.  See the illustration at 
http://www.ff.ul.pt/paginas/jvitor/SBAV/DrosophilaKaryotype.gif which is 
pretty much what you will find in any text book of genetics, going WAY back.

cheers

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