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)
Well done!
Strangely we are discussing some of this today as a sidebar on another thread which is otherwise exploring reality and illusions.
My two posts related to the subject of beginnings: 621 and 631.
That is just my point, neither the so-called Big Bang or evolution theories are proven truth...
Just because you claim they are by your religious faith in them does not lessen my criticism. I'm not an ecumenical or an orthodox atheist. Nothing is sacred to me.
Your only purpose here is to advance a religious attack on the godists, your own holy war. This crusade is as illogical as is your lack of evidence in defense of the Big Bang and the evolution of human beings.
The “missing link” is missing still, as is any logic to your arguments.
Some quantum events are truly random -- the condition most nearly the opposite of designed -- yet quantum theory is among the most useful theories we have.
To be fair, he or she may have specifically been referring to the emotional response to a child's face as non-scientific. But I can understand how it could be confusing, given that it appeared that he or she was using that as evidence in favour of ID, and an explanation that relies upon non-scientific "evidence" is typically itself non-scientific.
Of course there exists an intelligent designer...he is called 'Homo sapien sapien' and he is rather easily physically apprehended. The problem we have is the lack of evidence for and information about any other intelligent designer. That is not to say that this designer does not exist, just that we have no information about his design habits, intent or practices (without making some huge assumptions).
If this putative designer happens to design exactly as we do then we should be able to, at least in some cases, discern his/her/its work. That is as long as that designer doesn't use manufacture methods we have no experience with (much of how we identify design is through obvious manufacture) and doesn't do a perfect job of emulating nature. If this alien designer thinks differently than we do and consequently has designs that do not resemble human design we will have a heck of a time discerning his/her/its work. In addition to that, what if nature *can* create phenomena that looks every bit as organized and complex as an intelligent designer (and there is no evidence that it can not)?
We cannot see an intelligent designer, but there is ample physical evidence to support its existence, specifically organized matter that behaves purposefully and consistently. It is actual evidence that can be observed, measured, and studied. The observations made by this ultra-sensitive microscope are a case in point.
If you want to attribute the presence of organized matter that behaves purposefully and consistently to some other entity than intelligent design, then show your work.
We cannot see an intelligent designer, but there is ample physical evidence to support its existence, specifically organized matter that behaves purposefully and consistently.
Example? Actual, physical example not reliant upon impressions, feelings, intuitions or inference?
It seems to be a problem that extends only as far as a few narrow-minded ideologues. A single strand of DNA provides ample evidence of intelligent design. Science is beginning to quantify the amount of information processed through genetic material. How do you suppose it compares to the amount of information needed to build an automobile?
The presence of information is one evidence of intelligence. Do you think the presence of information is too hard for science to define and detect?
You want an actual, physical example of organized matter that behaves consistently and purposefully? Open your eyes.
I consider that a statement subject to futher scientific exploration and revision, just like matters concerning the presence, or absence, of an intelligent designer.
Funny how indirect evidence suits the purposes of science in every case except when it points to intelligent design. Why the blind spot?
If energy is applied, the result is not "spontaneous." Furthermore, both the applied energy and its result are, by virtue of design, quantifiable mathematically.
You want an actual, physical example of organized matter that behaves consistently and purposefully? Open your eyes.
I see.
You can't give me a specific example that can be studied, observed or measured. Instead, you are relying on your impressions of the natural world as "evidence."
Your feelings about the natural world are interesting, but not physical evidence.
Like I said, it's just my opinion. I may not be as knowledgable as some here, but I do believe I am entitled to my opinion.
In my humble opinion, Hitler was insane. So to say he was inspired by the Bible discounts the fact that he was crazy.
But that's just what I think.
The existence of information proves the existence of a designer? What proves that the 'information' is the result of a designer?
Science does not operate on the basis of emotion when it detects, quantifies, and handles organized, physical matter. A cubic inch of water consists of organized physical matter. It is quantifiable, predictable, physical, palpable, much like any designed obect. It also happens to behave purposefully, like any designed object. What is there about water that leads you to conclude scientifically that it is not designed? Or is it just your gut feeling?
I said nothing about proof. Don't put words in my mouth.
The math only works if it's truely random. The point you were attempting to make was that you can't do math on uncaused phenomena, but you are wrong.
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