From: Dan Clemmensen (email@example.com)
Date: Mon Feb 04 2002 - 18:24:09 MST
> Damien Broderick writes:
>>No. *Both* strands contain genes, running in
>>opposite directions. Did you know that? Am I the only idiot in the room?
> I did not know that, but come to think of it, it does make sense.
> Let's consider ourselves a little transcriptor machine, looking to read
> some DNA and make RNA from it. Here's some. Now, which strand is which?
> And which way is "forward"? The DNA extends for thousands of miles in
> each direction on our scale. It's twisted around itself so there is no
> way to distinguish one strand from a passive mirror. And one direction
> looks like the other. So there is no reason we can't read genes in
> either direction, and on either strand.
If I recall correctly, you are correct that the strands are locally
indistinguishable, but incorrect about the directions. Each strand has
a forward direction and a backward direction. The transcriber thingee
(DNA transcriptase?) runs only in the forward direction along whichever
strand it is on. The forward directions of the two strands are in
opposite directions. One end of a strand is called 3' (three-prime) and
the other is 5', but I've forgotten which is which.
dna transcription direction
I was almost right :-)
RNA polymerase (not DNA transcriptase) runs down the "wrong"
(i.e. antisense) DNA strand toward its 5' end, to build its
RNA complement (i.e. the RNA analogue of the "correct" DNA strand.)
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