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)
lay people trying to be physicists? madness....*shakes head*
"order tends towards disorder "....."a random jumble won’t organize itself "
obviously stated without any knowledge whatsoever of nonlinear mathematics and the "anti-chaos theory". This theory can be mathematically applied to any system (macroscopic or microscopic). see examples of anti-chaos or self ordering systems in genetics for example. where we do not see regression to lower order genome, but in fact movement towards complexity and order. This makes a nonsense of the above statement. This is not a closed system still the author is treating it as such
"The open systems argument does not help evolution. Raw energy cannot generate the specified complex information in living things.Undirected energy just speeds up destruction. Just standing out in the sun won’t make you more complex—the human body lacks the mechanisms to harness raw solar energy. "
Obvious error here, raw energy? a very unscientific term, energy changes STATE it cannot be destroyed in a closed or open system. The argument that solar energy cannot be harnessed by human beings is absurd. Human beings eat food that CAN harness solar energy, they eat predators that also eat food that can be harnessed by solar energy. Solar energy is also not the only form of ambient energy in our system. There is also radiation that stimulates genetic mutations. there are also quantum forces not treated by this comment and ignored. A buffoon wrote this IMHO.
" If you stood in the sun too long, you would get skin cancer, because the sun’s undirected energy will cause mutations. (Mutations are copying errors in the genes that nearly always lose information). "
Mutations if combined with the mechanism of natural selection are ALWAYS successful and select for robust and strong competing advantage over the encroached or incumbent species. The mutant gene will in the case of natural selection prevail at the expense of the less robust. In terms of mutation causing loss of information? explain how recombination events or other genetic mechanisms used by biological system to "capture" genetic material and extend the genome seem to fly in the face of this statement?
My conclusion is that this is a poor and crude attempt by a lay person, probably a PHD theologian to rebut topics and arguments he does not understand. It hurts his cause not helps it.
Keep living in your idealistic dream world .... I prefer reality.
;-)
The Big Bang theory was originally from a Jesuit astronomer...
The theory of evolution (‘the origin of species’), like the “Big Bang” theory, is based solely on the premise that life is an immaculate conception...
Categorical logic (Aristotle's logic) escapes you.
Is that true of the bacterial flagelum?
Well, I admit that I'm impressed that they attached a glass bead to each end of a DNA strand.
Much of the rest I'm trying to grasp.
Interesting. When you can't agree on definitions it makes debating difficult.
I always thought there was a pretty standard definition of that word. The standard definition as used in the Bible (and every other book I've ever read) is to bring into being or to cause to exist.
What is your own personal definition of "create"?
And while you are at it, what is your definition of "A Christian?" Do you believe such things as: The Deity of Christ? His Virgin Birth? His sinless life? His vicarious death on the cross for the atonement of your sins? His bodily resurrection?
Just Curious.
I take it you do not believe the Bible? Do you believe that God wrote the Ten Commandments with his own hand upon the Tablets? Or is that a fable?
Perhaps in matters of formal logic, yes, arguments from incredulity hold no water. But science is not pure, formal logic, nor does it need to use formal logic in order to be "scientific."
Fair 'nuff. Taken as showing flawed arguments for, I agree. But it still opens the door for the other...
Cheers!
I thought Balrog reserved that
post number (666) for himself. :-)
Cheers!
Agreed, but as a scientist definitions are important to me and should be established prior to any postulating. This does not make debate impossible it improves the quality of debate.
"I always thought there was a pretty standard definition of that word. The standard definition as used in the Bible (and every other book I've ever read) is to bring into being or to cause to exist."
Ah be careful, you have just generalized or created a generic definition of creation with that of the Bible's. Taken out of context this would be disastrous to any scientific or logical treatment of this subject.
My definition of creation in the context of the universe is reconciled with scientific principle. In other words I think God created the universe at a molecular level and "grew" it based on the principles he created at the time of the first molecule coming into existence. I do not believe he takes a direct hand in that creation after that moment, as that would rob free will from the equation, which God and Jesus in the new testament ministries promote. Free will is not just a function of expression with actions or choice, it has to also derive from the physical structure of space and time and matter. I am happy to debate this in more detail if you like.
"And while you are at it, what is your definition of "A Christian?"
This is defined by my religion
"Do you believe such things as: The Deity of Christ? His Virgin Birth? His sinless life? His vicarious death on the cross for the atonement of your sins? His bodily resurrection? "
Wholeheartedly
"Just Curious."
a human trait :-)
Oh, man! I just started reading this morning, am I'm at about post # 200.
So I had no idea...
FWIW, this is an interesting read, and I can't wait to see how it ends. 8^)
I hope the Freepers wo are arguing back at # 200 have settled their differences in a civil manner. ;^/
659 posted on 11/17/2005 4:34:56 AM CST by Ichneumon
As a non scientist, that's what I was hoping for when I started reading. Not so much discussion about the topic so far.
hmm some sarcasm / bitterness coming into the debate? I hope not. I fail to see how my statements could bring you to that conclusion. Please bear in mind:
2 Timothy 3:16: "All scripture is inspired of God......."
because someone has a different perspective to yours, please do not assume that this implies hostility or a need to attack that perspective. I hope we can genuinely discuss this without any angst?
"Do you believe that God wrote the Ten Commandments with his own hand upon the Tablets?"
Again I fail to see why this is brought into the discussion? a belief in this means what in the context of our debate? Can we stay on subject please? For the record not that it is germane I do believe in those accounts of the bible.
"Or is that a fable?"
Please point to where I have called the Bible a "fable" thats a little insulting to be honest please stop
I agree a real shame
As it seems to be impossible, I at least wish everyone couls stick to arguing without the snide remarks and personal attacks.
Never the less, I continue to read...only 400+ posts to go.
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