Many news sites have played up the idea that NASA scientists have made objects similar to cell membranes. As one site says, "They have succeeded in creating cell-like structures spontaneously from simple chemical ices in conditions that simulate the frigid vacuum of deep space." Is this claim really true? Let's look at the original article and see if it measures up to the claim.
An article, "Self-assembling amphiphilic molecules: Synthesis in simulated interstellar/ precometary ices" (authors Jason P. Dworkin, David W. Deamer, Scott A. Sandford, and Louis J. Allamandola, edited by Stanley Miller) claims to show that organic molecules can be formed under interstellar conditions in "molecular clouds" and that these organic mixtures can form "membranous vesicles" similar to lipid bilayer membranes found in living cells. The article was published in the non-peer-reviewed journal Proceedings of the National Academy of Sciences (PNAS). It is unlikely that the article would have passed peer-review, as you will soon see from this review.
The study began by using a gas mixture of water, methane, ammonia and carbon monoxide, which the authors claim are the prevalent gases found in interstellar clouds. However, these clouds are also known to contain significant amounts of carbon dioxide, which was not included in their mixture. Why this gas was left out and whether this omission would have any effect upon the resulting molecules was not discussed in the paper. The concentration of the gases was also not mentioned in the methods, but was likely to be much higher than that which is observed in real interstellar clouds.
The gases were deposited under vacuum onto a rotating nickel, aluminum, or brass substrate, cooled to 15°K (the approximate temperature of interstellar space). Are these the conditions that one would expect to find in interstellar space? First, rotating purified nickel, aluminum or brass is not available in space. They would have done better to use mixtures of metals similar to those found in meteorites.
The other unrealistic condition is that the gases (at room temperature, most likely) were directed at the pre-cooled metals, so that they would be frozen and concentrated beyond anything possible in interstellar space. In interstellar space, everything is cold and any frozen gases would not be expected to get concentrated on any solid substrate in this manner, except under extremely rare conditions, none of which I can think of at the moment.
Next, the concentrated, iced gases were irradiated with an extremely high level of ultraviolet radiation (1015 photons/sec). What is unrealistic about this scenario is that there would never be a radiation source in interstellar space that produced radiation in the narrow wavelengths (121 nm and 161 nm) produced by the hydrogen discharge lamp used in this study. Any source of radiation produced in space would have to come from some stellar or nebular object, all of which produce much larger amounts of radiation in the non-ultraviolet region of the electromagnetic spectrum.
The much higher energy radiation (gamma and x-rays) would be expected to be present, which would likely undo most, if not all of the effects the UV had upon molecules formed from the gases. In order to get a dose equivalent to that used in the study, there would also have to be large amounts of heat produced from the source, which would melt the ices and produce gas clouds. The basic premise that the conditions used in this study exist anywhere in this universe is flawed.
Believe it or not, things actually go downhill from here. In order to get the organic molecules, the gases were simultaneously deposited (at 15°K) and irradiated with the high dose UV for two days. After this time, the ice was slowly warmed to room temperature under static vacuum. Then the process was repeated (deposition at 15°K and simultaneous high dose UV for two days followed by warming) cyclically for a period of 5 weeks. What kind of interstellar object would produce this kind of cycle was not discussed in the article.
A single cycle experiment ("continuous photolysis and deposition for 4-7 days") was attempted (probably first), which "produce similar samples but with lower yields." Obviously, the yields were so much lower that the method could not be used to collect material for the remainder of the study, since the authors never demonstrated that the products were actually "similar samples".
The material was then eluted from the metal substrate with purified chloroform-methanol (not usually found in outer space), dried under flowing dry nitrogen (also not found in outer space) and redissolved in chloroform-methanol. Next, the dissolved mixture was separated by high pressure liquid chromatography (HPLC) columns (not usually found around stellar objects, excluding the Sun) into component chemicals.
The fractions from the column were added to phosphate buffered water (at alkaline pH). The amount of phosphate and pH of the buffer would almost certainly not be present on the earth at any time in its past. In fact, the phosphate problem is a serious one for those who postulate that nucleotides were formed on the early earth. Some of the HPLC-purified components of the organic mixture formed "water-insoluble droplets with different morphologies."
The authors conclude that the produced organic mixture, "show lipid-like behavior and self organize into droplets on exposure to liquid water suggest that extraterrestrial materials could exhibit a far greater range in chemical properties and behavior than previously thought." Of course, it would be expected that any long carbon chain molecules would form droplets in the presence of water.
This is not "self organization" but merely a property of organic and aqueous mixtures (like the old saying, "oil and water don't mix"). Organic mixtures must form droplets in the presence of water, since the energy keeping such "structures" together is less than that required to separate the hydrophobic parts of the molecules from the aqueous components. Therefore, none of this requires any kind of "self assembly."
The authors failed to demonstrate that these "membranous vesicles" actually had any properties in common with biological membranes. Real membranes must have the capacity to selectively include and exclude salts and organic molecules and selectively transport other such molecules. Without these abilities, these "membranous vesicles" would be completely worthless to house any kind of cellular machinery.
In conclusion, the study demonstrates incredible audacity to make the claim that biological membrane-like vesicles have been produced in conditions mimicking interstellar space. This review demonstrates that this claim is absurd, and that no place in the universe would ever exhibit the conditions found in the methods used to produce the organic mixture synthesized in this study.
In addition, the purification of the mixture through multiple artificial steps could never be reproduced in the universe except by intelligent beings in a laboratory on earth. The incredible lengths to which non-believers will go to avoid the conclusion that life must have been formed by an intelligent Being are quite spectacular. This blindness to rational critique seems to extend to the entire prebiotic life/astrobiology community, which seems to be unable to critically evaluate the irrationality of its "scientific" studies.
Interstellar Conditions? Astrobiologists have "simulated" interstellar conditions. Here is what they believed happened in space.
Purified metals became cooled to 15°K while mixtures of room temperature gases were shot at those metals. During this time, the gases frozen on the metals were bombarded with narrow wavelength ultraviolet light (no other frequencies of the electromagnetic spectrum were emitted by this unusual interstellar object (no gamma, x-ray or heat).
Every two days, however, this miraculous interstellar object produced enough heat to warm the metals to room temperature (no higher, of course). Then heat production suddenly ceased as the temperature dropped back to 15°K as more UV radiation was produced. This remarkable interstellar object then continued on these alternating cycles for 5 weeks.
Even more remarkable was the sudden production of chloroform:methanol directed at the metal bar, dissolving the organic molecules, then shooting out a purified burst of dry nitrogen gas (at room temperature) to dry the solvent.
The interstellar object then randomly assembled itself into a high pressure liquid chromatography column (complete with injectors, column packing, and detectors) to separate the material into fractions. At this time, the interstellar object crashed into the newly formed earth and landed, believe it or not, into a pool of 5 mM phosphate buffer.
The end result was a fully functional cell (no!), a functional biological membrane (no!), some oily blobs (yes!) in the pool. And that is how the astrobiologists think life began on earth!...
Gurmat Gyan (Knowledge)
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