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.
Its 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. Its pretty incredible. You would never have believed it could be possible 10 years ago.
Journal reference: Nature (DOI: 10.1038/nature04268)
Not once have I said that I "feel" the heavens and the earth are the product of intelligent design. Not once. An inference is not just an emotion, or a feeling. It is based upon evidence, and the evidence for intelligent design consists of the organized, predictable, consistent, tangible, dynamic behavior of matter as it functions under predictble, consistent laws. Not coincidentally, when humans design machines they want all of those qualities and more to apply.
All inferences are to its maker, The Grand Designer, GOD!
You may make whatever emotional inferences you like. Just don't pretend that those emotional inferences are physical evidence.
Words mean things, after all.
Scientific thought and testing is to lead to results of truth. ID is your assumption of that truth. You mistake the begining with the end. If you are so sure that what you will find is ID then by all means present testing. Show controls and results, then explain your findings as they relate to where you began.
The point exposed is that you do not do that. That is exactly why this is for Sunday school and not academic school. Until you can present these things keep ID out of my kids biology class.
you make a claim that can only be supported by blind assumption. If you are so sure that your assumption is proper then why leave it at assumption? That question answers itself.
Inferences are made on the basis of physical evidence. The physical evidence continues to reveal, as it should, order and design.
Inferences are made on the basis of physical evidence.
Yes, but that's the beginning of science, not the end. You're stuck on Square One and think you've gone around the board.
The physical evidence continues to reveal, as it should, order and design.
Should? Should? Your bias reveals itself. You're not interested in knowledge, only reinforcing your personal cosmology. That's not science at all - it's the opposite.
Is this another one of those "arguments from incredulity?" What is it that constitutes the "legitimacy" of a scientific body? Is it the degree to which they are able to rule out the "supernatural?" Hahahahaha!
Of course it does. Have I been unclear as to what my starting assumptions are?
Matter does more than simply exist. If that were all there is to it, there would be no science.
Don't you have a cosmology? Sure you do. And I'll bet all the evidence fits it just swell.
Do you have any physical evidence to substantiate this emotional inference, or is this just another one of your "unscientific" musings?
My beliefs have changed to fit the available facts. You seem to want to work it the other way around.
Now I'll ask my question again: Why do you suppose no legitimate scientific organization (that is to say, one that has a purpose other than promoting ID) recognizes ID as science? Some global conspiracy stretching back centuries? I'd really like to know.
Words mean things, after all.
Do you have any physical evidence to substantiate this emotional inference, or is this just another one of your "unscientific" musings?
Now you're not making sense.
It is illuminating, though, that someone who calls himself a conservative has a problem with words meaning things....
No. I said it is not unreasonable, or unscientific, to infer a designer when we see something that is designed. In a good many cases we may safely assume an object is intelligently designed, and we can do so without being "unscientific." In almost every case the evidence is indirect.
Nor is it unreasonable, or unscientific, to extrapolate from there and infer a designer in cases where "nature" is organized and performs functions as complex as, or more complex than, human implements.
Most scientific organizations that you would consider "legitimate" are johnny-come-lately philosophical societies who prefer to advance a particular ideology in the name of science. The answer is: they are not legitimate scientific institutions.
Ah, I get it.
There are no scientific standards, there are no legitimate scientific institutions, and words don't mean anything.
At least I now understand where you're coming from.
Hehehe. Let's take a car over to some aboriginal tribe and set it out in the forest without their knowledge. Then, when they happen upon it, we can record their reaction and see if they are so stupid as to think it sprung up out of the ground as a product of something totally unguided, totally undesigned, totally unintelligent. Just a fluke in every day matter. Just "nature taking its course." Hahahaha!
In case you didn't notice, regularity and order are inherent in items that are intelligently designed.
It is an unscientific standard to omit the possibility of occurences in physical matter that run contrary to established physical laws. The legitimacy of scientific institutions is based chiefly upon their ability to seek and obtain accurate knowledge about the fields of study in which they are engaged. Words do indeed mean things, and must be carefully applied in expressing what may, or may not, constitute objective reality.
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