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)
"Crap!"
I must have stated the truth ... I notice your articulate reply ... it's so typical of your kind ... .
Give it a lot of intertial mass and separate it from everything around it with very low pass shock absorbers.
Lots of existing scientific instrumentation works this way.
Of course, its typically expensive as heck, since you need to build a special floor just for the instrument.
Guess you will never realize that it's people that do bad things not Science. Par for the course.
"I like to ask this of everyone who posts this.
Very good idea.
"Show us your work. I'd like to see the calculations that demonstrate your conclusion.
How much activation energy needs to be overcome to jump start a creationist?
AHhh....
Then why don't we see MUCH more variety in existing critters today???
Seems to me that if this error rate is true, MANY neutral (Neither aiding nor detracting from 'advantage in reproduction') things would be hanging around most every critter alive!
Obviously, you understand neither the theory of evolution, nor the Big Bang theory. Your statement is wholly untrue.
And if someone posts that Hitler was an Evolutionist: Watch OUT!
Accepted.
"Guess you will never realize that it's people that do bad things not Science. Par for the course."
That's precisely what I am talking about and VERY CLEAR in my reply. I further qualify that with godless people.
Feeling a tad dense today? Or just prickly as usual?
Never mind, I really don't want to hear about your endless problems.
Just to keep the quantum wave joke alive, I have to ask: How quickly did the wave (H2O) decay? ;)
Romans 5:12-21
12. Therefore, just as sin entered the world through one man, and death through sin, and in this way death came to all men, because all sinned--
13. for before the law was given, sin was in the world. But sin is not taken into account when there is no law.
14. Nevertheless, death reigned from the time of Adam to the time of Moses, even over those who did not sin by breaking a command, as did Adam, who was a pattern of the one to come.
15. But the gift is not like the trespass. For if the many died by the trespass of the one man, how much more did God's grace and the gift that came by the grace of the one man, Jesus Christ, overflow to the many!
16. Again, the gift of God is not like the result of the one man's sin: The judgment followed one sin and brought condemnation, but the gift followed many trespasses and brought justification.
17. For if, by the trespass of the one man, death reigned through that one man, how much more will those who receive God's abundant provision of grace and of the gift of righteousness reign in life through the one man, Jesus Christ.
18. Consequently, just as the result of one trespass was condemnation for all men, so also the result of one act of righteousness was justification that brings life for all men.
19. For just as through the disobedience of the one man, the many were made sinners, so also through the obedience of the one man the many will be made righteous.
20. The law was added so that the trespass might increase. But where sin increased, grace increased all the more,
21. so that, just as sin reigned in death, so also grace might reign through righteousness to bring eternal life through Jesus Christ our Lord.
Hold this thought........
Why should I be astonished?
All knowledge depends on scale.
I am impressed.
They got enough worries of their own: wondering whether their good deeds will outweigh the bad on Allah's scales......
Why is this a BAD thing??
Must IDer's be atheists now?
Don't Haeckel the poor lamb, he has probably been using PatrickHenry's troll toolkit, he managed several of the standard creato-trolling points in one post, and it's not as if he's a newby.
After a re-read; did you mean BIAS??
Do you have anything to add other than insult?
Just projections. Why do you hate so much?
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