On Tue, 19 Feb 2008 04:18:06 -0800 (PST), dsummerstay@[EMAIL PROTECTED]
wrote:
>How is it possible for DNA to reproduce at the speeds it does? DNA
>bases find their place at a rate of up to 1000 base pairs per second
>at a replication site. I have a hard time picturing this. Imagine a
>string encrusted with magnets, thrown into a bag of short magnetic
>clusters and shaken rapidly. I can imagine, if the design was clever
>enough, that occasionally a cluster would find its proper place at the
>end of the string, as the clusters got knocked around and one just
>happened to land at the right angle to get knocked into the right
>place to join at the end of the string. But this would be a very slow
>process. Most of the time, the clusters would block each other by
>fitting in a not quite perfect way (a local energy minimum) rather
>than instantly finding a perfect fit (a global energy minimum). How
>does it happen so fast in the cell?
The same way it does in your imagined bag of magnets, only about a
million times faster. The mechanism is the same, and the DNA bases
are probably bouncing around due to brownian motion at about the
same speed you are imagining the magnets bouncing around, but the
DNA bases only need to move a dozen or so *nanometers* between each,
"Do I fit in this spot at this angle? Nope; time to bounce off and
try again", whereas your thought-experiment magnets have to move a
dozen or so millimeters each time.
The smaller a thing is, the faster it will do whatever it does. And
molecules are really, really, really small.
So if you find it necessary to imagine things being a million times
larger than they actually are to visualize what's going on, you have
to keep in mind that you have similarly magnified the time scale.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*John.Schilling@[EMAIL PROTECTED]
* for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
|
