Dueling bubbles? Give me a break...
Posted on 09/03/2004 6:49:50 AM PDT by PatrickHenry
Howard Hughes Medical Institute researchers are proposing that the first battle for survival-of-the-fittest might have played out as a simple physical duel between fatty bubbles stuffed with genetic material. The scientists suggest that genetic material that replicated quickly may have been all the bubbles needed to edge out their competitors and begin evolving into more sophisticated cells.
This possibility, revealed by laboratory experiments with artificial fatty acid sacs, is in sharp contrast to a current theory of the earliest evolution of cells, which suggests that cellular evolution was driven by primordial genetic machinery that actively synthesized cell membranes or otherwise influenced cell stability or division.
The researchers, led by Howard Hughes Medical Institute investigator Jack W. Szostak, published their findings in the September 3, 2004, issue of the journal Science. Szostak and first author Irene Chen, both from Massachusetts General Hospital and Harvard Medical School, collaborated on the studies with Richard Roberts of the California Institute of Technology.
Cells are basically sacs encapsulated by bilayered membranes of fatty acids and other lipids, plus proteins. A central question in evolution is how simple versions of these cells, or vesicles, first arose and began the process of competition that drove the evolution of life.
"Most of the previous thinking about how cells grew and evolved was based on the idea of the initial evolution of structural RNAs or ribozymes -- enzymes that could synthesize membrane molecules," said Szostak. The ribozymes might have made more membrane material while the structural RNAs might have formed a cytoskeleton that influenced stability, shape, growth or division, he said. However, Szostak and his colleagues theorized that a far simpler physical process might explain why cells would compete with one another for the materials necessary to expand their size.
"We proposed that the genetic material could drive the growth of cells just by virtue of being there," he said. "As the RNA exerts an osmotic pressure on the inside of these little membrane vesicles, this internal pressure puts a tension on the membrane, which tries to expand. We proposed that it could do so through the spontaneous transfer of material from other vesicles nearby that have less internal pressure because they have less genetic material inside."
In order to test their theory, the researchers first constructed simple model "protocells," in which they filled fatty-acid vesicles with either a sucrose solution or the same solvent without sucrose. The sucrose solution created a greater osmotic pressure inside the vesicles than the solvent alone. The membranes of the simple vesicles were not as sophisticated as the membranes of today's living cells, said Szostak. However, they closely resembled the kinds of primordial vesicles that might have existed at the beginning of evolution.
When the scientists mixed the two vesicles, they observed that the ones with sucrose - in which there was greater membrane tension - did, indeed, grow by drawing membrane material from those without sucrose.
"Once we had some understanding that this process worked, we moved on to more interesting versions, in which we loaded the vesicles with genetic molecules," said Szostak. The researchers conducted the same competition tests using vesicles loaded with the basic molecular building blocks of genetic material, called nucleotides. Next, they used RNA segments, and finally a large, natural RNA molecule. In all cases, they saw that the vesicles swollen with genetic material grew, while those with no genetic material shrank.
It is important to note, said Szostak, the concentrations of genetic material that his group used were comparable to those found in living cells.
"In contrast to the earlier idea that Darwinian competition at the cellular level had to wait until the evolution of lipid-synthesizing ribozymes or structural RNAs, our results show that all you would need is to have the RNA replicating," said Szostak. "The cells that had RNA that replicated better -- and ended up with more RNA inside -- would grow faster. So, there is a direct coupling between how well the RNA replicates and how quickly the cell can grow. It's just based on a physical principle and would emerge spontaneously," he said.
According to Szostak, the next step in the research will depend on another major effort under way in his laboratory to create artificial, replicating RNA molecules.
"If we can get self-replicating RNAs, then we can put them into these simple membrane compartments and hope to actually see this competitive process of growth that we are hypothesizing," he said.
Do you also assume that a thunderstorm “feels and urge” when it competes with a wild fire?
"Why would a very particular chain of organic molecues feel "compelled," or even bother "trying," to reproduce itself?"
Do you assume that Francis “feels compelled, or is even bothering trying” to grow?
A few initial tiny anisotropies, the expansion of the universe with its consequent cooling, and the laws of physics [especially gravity]. The universe indeed loses potential energy and "winds down" over time. That satisfies the second law. Things cool off, fall together under gravity, cook off nuclear fuel, blow up in big supernovae, etc. But things also get more complicated, full of geographical features instead of a near-uniform hot gas. Complexity is allowed to emerge so long as overall entropy increases. It does.
Why not? They find a rock in Antarctica and somehow KNOW that it came from Mars. How they know it came from Mars and not the Earth, Moon, an asteroid, or a meteorite is beyond me.
There are extremists that go too far in every ideology. No need to call them names. That's being a "dork".
We’ve got bigger battles now than to divide ourselves on this age old question.
Hey, I didn't start the "Dorks" thing. But I should have included a ;) so my intent was clear.
We will always have bigger battles to fight. By that logic, these boards should only ever display one united opinion.
Weird...but interesting...
They don't. Some of them are simply better replicators than others which means that they eventually replace the slower ones.
They don't. Some of them are simply better replicators than others which means that they eventually replace the slower ones.
It's beyond you only because: (a) you assume -- with no justification whatsoever -- that scientists behave like a bunch of swamis; and (b) you haven't bothered to find out how scientists came to their conclusion. If you really care about the issue, this will get you started:
Why are scientists so sure that the Martian meteorite that has been in the news recently really came from Mars?
*CHAMPAGNE POP*
We understand the "how", but we'll never understand the "why"! /creatidiot mode
Isotope ratios. I personally have a piece of a Mars meteroite.
Oh! Well BACK TO THE ELECTION...
This theory isn't really new entirely, only the underlined details seem to be actually new. They've done experiments with lipid bubbles forming membranes on their own for awhile now.
The interesting part is that they seem to start 'eating' spontanously at a very early stage. Next stage is getting them to split and reproduce. All with nothing more than a few common chemicals and energy. Before you know it (well, billions of years) you have bacteria, plants, animals, people.
This is pretty definitive proof that life is nothing more than a completely natural event, and probably widespread throughout the universe.
"irrepressible optimist: a proponent of the doctrine that black is white"
[Ambrose Bierce, The Devil's Dictionary]
Beer..the meaning/origin of life on Earth is (based on formulating of) BEER. Who'll drink to that, the Egyptians/Germans/Babylonians had it right, all along? ...Open a "COLD ONE" (Bud, Coors, Iron City, Miller :))
Bubbleheaded bump.
The Almighty started and directed the process, regardless of what the process was.
Yes that is science. Scientific theories are always qualified like this because at any time, even a theory that has been accepted for hundreds of years can be shown to be incorrect. (Ask Isaac Newton about this, for example). Furthermore, no amount of evidence can prove a scientific theory correct. Science is always speculative to some degree.
This BS just like the article
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