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Graham Dellaire (popa0206 at PO-Box.McGill.CA) wrote:
: > 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 differen
t reading frames in
: on either strand for a given section of DNA ( Adeno-2 for example). This is p
robably 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 transcr
ibed... 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.....
: -
In addition, it is easier to check the accuracy of sequencing of the
DNA if one can look at the complimentary strand after replication.
