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translating DNA question

Graham Dellaire popa0206 at PO-Box.McGill.CA
Sat Jul 22 15:35:36 EST 1995

>   monty at watson.open.ac.uk (Tony Hirst) writes:
>  Another novice question....
>  the complementary strands of DNA, when trnascribed between two points, will
>  translate to two different sequences depending on which strand of the helix
>  is transcribed.
>  Qn: are the decoded complementary sequences both necessarily 'useful' (i.e.
>  not nonsensical) or does DNA employ complementarity solely to facilatate
>  replication and repair?

Both strands can yield functional proteins... I think a good example would be viral DNA which
can have different functional proteins encoded by the same DNA but in different reading frames in
on either strand for a given section of DNA ( Adeno-2 for example).  This is probably because
of constraints on size of the virus' genome.  In mammalian cells you have the Rag-1 and Rag-2 
genes (responsible for VDJ recombinase activity) that are convergently transcribed... for this reason
they are hypothesized to have been derived from a fungal transposable element many eons ago.

 The obverse of this is that as well as multiple
-  coding over a single sequence through frameshifts, multiple coding is
-  achieved through DNA's dual-strand nature.....

-  Rep[ies via email preferably, or to the CSTB list

-  (Majordomo at biome.bio.ns.cs)...
>  thanks in advance
>  tony hirst
>  ps - replies to my previously posted 'genetic code & mutation rates' are
>  still sought after..
>  --------------------------------------------------------------------------
>   All opinions etc etc...
>  --------------------------------------------------------------------------
>        | Tony Hirst ("Monty")          | e-mail:  A.J.Hirst at open.ac.uk
>         -------------------------------------------------------------------
>        | "There is no meaning..."         "Science is a subset of art..."
>         -------------------------------------------------------------------

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