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)
ID is creationism wearing an ill-fitting condom.
Behe has suggested that the flagellum would be a great test. Given advances in nanotechnology and microbiology, one can at least plot out a path to constructing them, probably within the next 20-50 years. The ID hypothesis could be falsified if one were to construct a test whereby we could observe flagella developing through a process of evolution. Behe's claim that ID is "necessary" for the development of flagella would be invalidated.
This would merely show a flaw in Behe's anti-evolution argument (as if that hasn't *already* been done by pointing out his multiple fallacies). It would in no way falsify ID. Try again.
IDers keep making the mistake of thinking that evidence *against* evolution is somehow evidence *for* ID, when it is not. Conversely, the falsification of an anti-evolution argument is not falsification of ID either.
Which of course raises a corollary question: the current hypothesis is that flagella evolved. Has anybody ever tested it?
Yes, in part, by identifying precursor systems which evolution could have adapted in "constructing" the flagellum, and by identifying simpler "proto flagella" that still function as motile systems. I believe some work is being done on comparative sequence analysis of the genes responsible for flagella as well.
The Bible does not depend on my interpretation for its veracity any more than the rest of the world depends upon you to define what science is, or is not.
And where that RNAP bound to the DNA - one will find something very interesting akin to:
a man a plan a canal panama
or
rise to vote sir
gene expression - it's a wonderful thing
I choose Irreducible Complexity as the hypothesis, and the Krebs Cycle as the subject of the test.
Take any fact you want. If it is not falsifiable, does that make it "unscientific?"
"I think little gnomes created the different species. I see evidence all around me that they did it. It's up to the Evolutionists to prove why science has to reject the Gnome Theory."
Wrong. If you propose your theory as a scientific alternative to other theories, you *have* to have some form of evidence to support it, and a credible explanation why it's superior to existing theories. Evolutionary Biologists don't have to do Jack S**T about ID unless the ID advocates meet the above criteria. That's how science has worked for the last few hundred years, and it's worked very well.
Should I not?
"Take any fact you want. If it is not falsifiable, does that make it "unscientific?"
We are talking theories, not facts. You don't seem to know the difference.
So I repeat,
What possible use is a *theory* that no conceivable evidence can go against?
It is if its proponents want it taught in science classes.
I admire a scientist who is courageous and humble enough to use the word "probably". Such a scientist is probably not an empiric.
The presence of organized matter carrying out numerous functions resulting in life and the ability to observe it is enough evidence for me, and for most people.
So a number of ideologues say.
I'm guessing that you're new to these threads. It's almost impossible to start a thread on science on FreeRepublic without having a sudden wave of IDers/creationists come rushing in with claims that the article either a) proves God, or b) is an example of godless scientists trying to turn people away from God with false materialistic doctrine, blah blah blah.
Consequently, it's not out of line to try to cut them off at the pass, or at least pre-empt them.
I *do* wish we could have a science discussion that just talked about the science, but that has proven to be an unachievable goal here.
The problem is that this is a classic case of begging the question.
You're using your presumption in order to view the evidence as supporting your presumption. You have in no way *tested* your postulate.
Par for the course.
It most certainly *is*, if they want to elbow their way into science classrooms and have it presented there.
the evidence of intelligent design is more voluminous than the evidence for its opposite.
Complete horse manure. You haven't a clue what actually constitutes evidence for a hypothesis. It's not just whatever you feel like looking at which makes you think maybe your hypothesis might explain it, which is clearly how you're using the term.
You have to actually be able to *test* your hypothesis against the evidence for the evidence to actually be supportive of your hypothesis. To date, "ID" has utterly failed to do that. Meanwhile, evolution has been tested against the evidence litterally *millions* of times and passed with flying colors.
There is a vast, *enormous* body of evidence and research -- along multiply independent cross-confirming lines -- supporting evolution. There is none whatsoever supporting the "ID postulate".
You and your ilk would like to make "falsifiability" the test of ID, as if ID must be falsifiable to be scientific. I am saying that is not true. It is possible for statements and pursuits to be scientific without being falsifiable. I know it's a hard pill to swallow. Deal with it.
I am also saying that, just because God is not currently subject to direct observation does not mean all mention or use of such a paradigm must be ruled as unscientific. Another bitter pill to swallow. Your mind may not be capable of that kind of expansion, but deal with that too.
The remark may be right or wrong, offensive or convicting but what is "condescending" about it? Who is he condecending to, and how? And besides, if most Christians do not know what the Bible says, we deserve a bad name. We don't need someone who simply points out the obvious truth to give us one.
You are a Christian and yet you do not believe that life was intelligently designed? I'm having trouble comprehending that concept. Help me out here.
Perhaps if you defined what it means to you to be a Christian.
Can one be a Christian and yet reject the idea that God made the heavens and the earth and all that in them is?
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