Free Republic
Browse · Search
News/Activism
Topics · Post Article

Skip to comments.

Ultra-sensitive microscope reveals DNA processes
New Scientist ^ | November 15, 2005 | Gaia [sic] Vince

Posted on 11/16/2005 3:40:35 AM PST by snarks_when_bored

Ultra-sensitive microscope reveals DNA processes

    * 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)


TOPICS: Culture/Society; Extended News; Miscellaneous
KEYWORDS: biology; chemistry; crevolist; dna; microscopy; rna; rnap; science
Navigation: use the links below to view more comments.
first previous 1-20 ... 921-940941-960961-980 ... 1,201-1,219 next last
To: Elsie
Snowflakes Prove that GOD exists and interacts with His creation.

I prefer Benjamin Franklin as attributed:

"Beer is proof that God loves us and wants us to be happy." :-)

and my corollary:

"Hangovers prove we are a fallen race." :-(

941 posted on 11/17/2005 6:38:49 PM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
[ Post Reply | Private Reply | To 743 | View Replies]

To: Elsie
A c++ programmer!

Fortran forever!

...oh, and vi too. :-)

942 posted on 11/17/2005 6:39:53 PM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
[ Post Reply | Private Reply | To 747 | View Replies]

To: PatrickHenry
The current situation just isn't interesting at all.

Roughly as interesting as watching a drunk trying to cross a busy intersection, and for the same reason.

943 posted on 11/17/2005 6:41:10 PM PST by longshadow
[ Post Reply | Private Reply | To 939 | View Replies]

To: longshadow; Fester Chugabrew

How about this ?

"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."

And then,

"Much good science is born of hunches, as well as logical fallacies."

Uncle Fester is a well that never runs dry. :)


944 posted on 11/17/2005 6:41:55 PM PST by CarolinaGuitarman ("There is a grandeur in this view of life...")
[ Post Reply | Private Reply | To 931 | View Replies]

To: Sir Francis Dashwood

The chip sets in your computer don't add to your knowledge of the universe?

When my lab partner dropped our photographically etched silicon wafer attempt to create a diode ( required to get credit in this semiconductor EE class ), and it disintegrated in the ultrasound bath and we had to start all over again, I didn't think it added significantly to my knowledge of the universe, but it did add to my knowledge.

945 posted on 11/17/2005 6:42:23 PM PST by ml1954 (NOT the disruptive troll seen frequently on CREVO threads)
[ Post Reply | Private Reply | To 927 | View Replies]

To: Ichneumon
Nice cherry picking on Hitler.

But if you actually dig a bit deeper, you'll run into other stuff...

The quote "One is either a German or a Christian, you cannot be both" (which the Brits turned into a propaganda poster juxtaposed with a photo of bombed-out city buildings...)

The contents of some Nazi-era school textbooks, with nice lines like "Jesus and Hitler were both persecuted; but while Jesus was crucified, Hitler went on to become chancellor"

The persecution of the Jews (read up on the Old Testament promises to Abraham about how God expected the Jews to be treated; or the New Testament writings of Paul about the Jews being subjected to a temporary hardening of their hearts, in order that God show mercy on goyim as well :-)

etc.

The cheap shots are unbecoming of you...

Cheers!

946 posted on 11/17/2005 6:46:54 PM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
[ Post Reply | Private Reply | To 803 | View Replies]

To: CarolinaGuitarman; RadioAstronomer
They're good, but they lack the pithy punch of "wildly elliptical planetary orbits" or "proving the Pythgorean Theory"....

It's truly an art form to cram so much that is so wrong into so few words.

947 posted on 11/17/2005 6:48:30 PM PST by longshadow
[ Post Reply | Private Reply | To 944 | View Replies]

To: Ichneumon
with any of these 700+ standard creationist flawed claims about evolutionary biology, we've seen those a thousand times already.

700 x 1000 = 7.0 x 105

How much time do you spend on these threads?

948 posted on 11/17/2005 6:49:18 PM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
[ Post Reply | Private Reply | To 821 | View Replies]

To: grey_whiskers
The quote "One is either a German or a Christian, you cannot be both" (which the Brits turned into a propaganda poster juxtaposed with a photo of bombed-out city buildings...)

Keep in mind that there is quite a bit of contention regarding the accuracy of much of the research on Hitler by the man who quoted Hitler as saying this.
949 posted on 11/17/2005 6:51:22 PM PST by Dimensio (http://angryflower.com/bobsqu.gif <-- required reading before you use your next apostrophe!)
[ Post Reply | Private Reply | To 946 | View Replies]

To: ml1954
IIRC, Einstein admitted that math was not one his strengths.

OK, fair enough as far as it goes.

But he was so intelligent anyway, that he could probably wipe the floor with most of the people on this thread in mathematics.

By analogy Randy Johnson's off-speed pitches are still faster than what most people on this thread could manage to throw; even though they're not fast "for him".

950 posted on 11/17/2005 6:58:42 PM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
[ Post Reply | Private Reply | To 923 | View Replies]

To: Dimensio
Keep in mind that there is quite a bit of contention regarding the accuracy of much of the research on Hitler by the man who quoted Hitler as saying this.

More details? I was quoting a contemporary British propaganda poster; and was unaware of the quote as being connected to any research on Hitler, controversial or otherwise.

Cheers!

951 posted on 11/17/2005 7:03:45 PM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
[ Post Reply | Private Reply | To 949 | View Replies]

To: longshadow; CarolinaGuitarman
It's truly an art form to cram so much that is so wrong into so few words.

Takes many "years" of education to accomplish such feats. :-)

952 posted on 11/17/2005 7:04:10 PM PST by RadioAstronomer (Senior member of Darwin Central)
[ Post Reply | Private Reply | To 947 | View Replies]

To: grey_whiskers

But he was so intelligent anyway, that he could probably wipe the floor with most of the people on this thread in mathematics.

By analogy Randy Johnson's off-speed pitches are still faster than what most people on this thread could manage to throw; even though they're not fast "for him".

OK. But Einstein admitted he needed help with the math for his theories and sought it from his contemporaries.

If Randy is smart, he's done the same. He may have natural talent, but I'd guess he'd be the first to say his coaches have helped him immensely.

953 posted on 11/17/2005 7:08:37 PM PST by ml1954 (NOT the disruptive troll seen frequently on CREVO threads)
[ Post Reply | Private Reply | To 950 | View Replies]

To: grey_whiskers
More details? I was quoting a contemporary British propaganda poster; and was unaware of the quote as being connected to any research on Hitler, controversial or otherwise.

The quote comes from Hermann Rauschning, and the Wiki link there seems relatively unbiased, if brief. There's mention of the controversy surrounding some of his work there. I found other references on Rauschning from Google, but I'm not sure I want to take the time to sort out the genuine skeptics of his work from the foaming-at-the-mouth historical revisionists who want to deny the Holocaust entirely.
954 posted on 11/17/2005 7:08:42 PM PST by Dimensio (http://angryflower.com/bobsqu.gif <-- required reading before you use your next apostrophe!)
[ Post Reply | Private Reply | To 951 | View Replies]

To: Dimensio
Oh yes, and you also have Hitler's eulogy upon Hindenberg, ending with "...enter thou upon Valhalla" ; which is quite a strange remark for a Bible-believer to make at a funeral. Still more so for them to have made it in the early 1900's when PDF's (public displays of faith, not the Adobe file) were not frowned upon.

Will have to see--if I ever find the time--if there are other sources for the quote about "either a German or a Christian."

Cheers!

955 posted on 11/17/2005 7:13:15 PM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
[ Post Reply | Private Reply | To 954 | View Replies]

To: Dimensio
...you have to take to dishonest misrepresntation of the statements of others?

Anyone who thinks mathematics is not science is a dope...

956 posted on 11/17/2005 7:16:38 PM PST by Sir Francis Dashwood (LET'S ROLL!)
[ Post Reply | Private Reply | To 938 | View Replies]

To: Sir Francis Dashwood
Anyone who thinks mathematics is not science is a dope...

Well, I guess that settles it then. I don't know how to counter the sound logic and airtight reasoning of the appeal to ad hominem. By insulting anyone who disagrees with you, you've surely proven your point far better than you could by citing actual evidence.
957 posted on 11/17/2005 7:20:22 PM PST by Dimensio (http://angryflower.com/bobsqu.gif <-- required reading before you use your next apostrophe!)
[ Post Reply | Private Reply | To 956 | View Replies]

To: Dimensio
the appeal to ad hominem

That is the whole point of while you are here to begin with, isn't it? You are here to bash the religionists.

It only frustrates you that it doesn't work with an atheist. Of course, since I am an equal opportunity secularist: I take shots at atheists too, because some of you are no better, and most often times worse, than the godists.

Ad hominem - - latin - - to the man....

_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-

By insulting anyone who disagrees with you...

argumentum misericordian - - latin - - appeal to sympathy

Go get a tissue...

958 posted on 11/17/2005 7:35:55 PM PST by Sir Francis Dashwood (LET'S ROLL!)
[ Post Reply | Private Reply | To 957 | View Replies]

To: js1138

Were some QM events not random, we wouldn't be having this discussion. (At least not using a semi-conductor based device.)


959 posted on 11/17/2005 7:38:21 PM PST by Doctor Stochastic (Vegetabilisch = chaotisch ist der Charakter der Modernen. - Friedrich Schlegel)
[ Post Reply | Private Reply | To 860 | View Replies]

To: Sir Francis Dashwood

Anyone who thinks mathematics is not science is a dope.

Then you are a dope. Math is abstract. Science attempts to describe reality. Ignoring left-wing postmodern decontrunctionist hypothesis' of reality (I'm guessing you don't subscribe to these), Science is not abstract. Math is a tool used by science to describe reality.

960 posted on 11/17/2005 7:43:04 PM PST by ml1954 (NOT the disruptive troll seen frequently on CREVO threads)
[ Post Reply | Private Reply | To 956 | View Replies]


Navigation: use the links below to view more comments.
first previous 1-20 ... 921-940941-960961-980 ... 1,201-1,219 next last

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.

Free Republic
Browse · Search
News/Activism
Topics · Post Article

FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson