General interest questions

Greg Broadhead gregb at sciborg.uwaterloo.ca
Fri Feb 18 10:54:43 EST 1994


In article <2k0dd7$4iu at homer.cs.mcgill.ca>,
Jacob BROSTOFF <jayjay at cs.mcgill.ca> wrote:
>Someone asked about genome sizes ... from my intro genetics notes:
>                  DNA length / cell              est. no of genes
>Lambda phage           17 microns                   50-60
>T4 phage 	       70                           200	
>E Coli                 1 000                        3000
>Drosophila             1 600                        approx 50 000
>Homo Sapiens           1.74 metres                  apporx 200 000
>
>BUT!
>
>Necturus ('mud puppy') has 17.5 times longer DNA / cell than homo sapiens,
>trilliums have 18.5 times more, and Amphiuma ('congo eel') have 26 times
>more (approx 130 feet)	
>
>so usually, it gets bigger as you go up the evolutionary ladder, but not 
>always.
>
>j

 I believe this is called the C value Paradox.  The ammount of DNA an
organism has, or chromosome number has very little to do with the
complexity of it.  Viruses have small ammounts of DNA/RNA due to size
constraints of the head.  Also large chains of DNA are a) hard to get
intoa host cell, and b) more suceptible to damage from restriction
enzymes.  With most other organisms, especially Eukaryotic ones BP#'s have
very little to do with complexity.

--Greg




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