Posted on 11/16/2005 3:40:35 AM PST by snarks_when_bored
* 14:02 15 November 2005
* NewScientist.com news service
* Gaia Vince
A new microscope sensitive enough to track the real-time motion of a single protein, right down to the scale of its individual atoms, has revealed how genes are copied from DNA – a process essential to life.
The novel device allows users to achieve the highest-resolution measurements ever, equivalent to the diameter of a single hydrogen atom, says Steven Block, who designed it with colleagues at Stanford University in California.
Block was able to use the microscope to track a molecule of DNA from an E.coli bacterium, settling a long-standing scientific debate about the precise method in which genetic material is copied for use.
The molecular double-helix of DNA resembles a twisted ladder consisting of two strands connected by “rungs” called bases. The bases, which are known by the abbreviations A, T, G and C, encode genetic information, and the sequence in which they appear “spell out” different genes.
Every time a new protein is made, the genetic information for that protein must first be transcribed from its DNA blueprint. The transcriber, an enzyme called RNA polymerase (RNAP), latches on to the DNA ladder and pulls a small section apart lengthwise. As it works its way down the section of DNA, RNAP copies the sequence of bases and builds a complementary strand of RNA – the first step in a new protein.
“For years, people have known that RNA is made up one base at a time,” Block says. “But that has left open the question of whether the RNAP enzyme actually climbs up the DNA ladder one rung at a time, or does it move instead in chunks – for example, does it add three bases, then jump along and add another three bases.
Light and helium
In order to settle the question, the researchers designed equipment that was able to very accurately monitor the movements of a single DNA molecule.
Block chemically bonded one end of the DNA length to a glass bead. The bead was just 1 micrometre across, a thousand times the length of the DNA molecule and, crucially, a billion times its volume. He then bonded the RNAP enzyme to another bead. Both beads were placed in a watery substrate on a microscope slide.
Using mirrors, he then focused two infrared laser beams down onto each bead. Because the glass bead was in water, there was a refractive (optical density) difference between the glass and water, which caused the laser to bend and focus the light so that Block knew exactly where each bead was.
But in dealing with such small objects, he could not afford any of the normal wobbles in the light that occur when the photons have to pass through different densities of air at differing temperatures. So, he encased the whole microscope in a box containing helium. Helium has a very low refractive index so, even if temperature fluctuations occurred, the effect would be too small to matter.
One by one
The group then manipulated one of the glass beads until the RNAP latched on to a rung on the DNA molecule. As the enzyme moved along the bases, it tugged the glass bead it was bonded too, moving the two beads toward each together. The RNAP jerked along the DNA, pausing between jerks to churn out RNA transcribed bases. It was by precisely measuring the lengths of the jerks that Block determined how many bases it transcribed each time.
“The RNAP climbs the DNA ladder one base pair at a time – that is probably the right answer,” he says.
“It’s a very neat system – amazing to be able see molecular details and work out how DNA is transcribed for the first time,” said Justin Molloy, who has pioneered similar work at the National Institute for Medical Research, London. “It’s pretty incredible. You would never have believed it could be possible 10 years ago.”
Journal reference: Nature (DOI: 10.1038/nature04268)
There is more than a shred of evidence for organized matter and, by extension, and intelligent designer. There is less than an apology for calling you an ass.
I hardly think the phyisical attributes of DNA to be devoid of statistical/mathematical analysis, and thus arguments pointing toward the reasonable inference of intelligent design.
But pot
Hits the spot
You must know the mind of Fester better than Fester. Are you the one I've been praying to all these years?
Please explain the difference between a "starting premise" and a "conclusion."
Thanks for the explanation.
Wow. That's the best indictment of "ID is science" that I've seen so far. Thanks.
Which...brings...us...back...to...DOE! (D'OH !) ;-) ;-) ;-)
From the first post on this thread: "Anybody who reads this article and feels no astonishment is either stupid or not paying attention."
That's okay. You're right, too. I am motivated by a tautology that has scientific veractiy: God created the heavens and the earth and keeps them going. They are intelligently designed in a fashion that exceeds the intelligence of His creation. He knows their ulitimate purpose and direction.
His creation, the human portion, struggles to comprehend His magnificent works. That small segment of His creation engages in science. They can't even figure out that oil is not the be all and end all of energy. They're so stuck in evolutionist notions they can't conceive there is enough energy in a single kernel of corn to electrify 28 LEDS on a red light whore board.
I delight to inform you that the evidence for black holes is inferential at this time. No one has touched one. Would you care to be the first?
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