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TOPIC: Ingredients for life
Blobrana


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Polycyclic aromatic hydrocarbons
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Tantalising traces of the building blocks of life have been spotted in nearby galaxies. However, working out the identity of these carbon-containing molecules, and when they became abundant, is proving tricky, say astronomers.
Astrophysicists believe that organic molecules were present in the cloud of dust and gas from which our solar system formed, providing the raw materials for life on Earth. Astronomers can see these molecules throughout our galaxy, which is one reason why many believe conditions may also be ripe for life in other parts of the Milky Way, and perhaps further afield.
So the hunt is on to find these molecules in other galaxies. By looking at galaxies similar to our own, but at an earlier stage of their evolution, astronomers hope to work out how long these molecules have been abundant in the universe, and therefore how long the conditions suitable for life as we know it have prevailed.
The chemical signature of a class of organic compounds called polycyclic aromatic hydrocarbons can be seen in the way they absorb light from distant stars. The molecules are thought to leave a complex pattern of dark bands in these spectra called diffuse interstellar bands (DIBs).

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Blobrana


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Information, Reproduction and the Origin of Life
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In January 1955, Homer Jacobson, a chemistry professor at Brooklyn College, published a paper called Information, Reproduction and the Origin of Life in American Scientist, the journal of Sigma Xi, the scientific honour society.
In it, Dr. Jacobson speculated on the chemical qualities of earth in Hadean time, billions of years ago when the planet was beginning to cool down to the point where, as Dr. Jacobson put it, one could imagine a few hardy compounds could survive.

Nobody paid much attention to the paper at the time, he said in a telephone interview from his home in Tarrytown, N.Y. But today it is winning Dr. Jacobson acclaim that he does not want from creationists who cite it as proof that life could not have emerged on earth without divine intervention.
So after 52 years, he has retracted it.

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Blobrana


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RE: Ingredients for life
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Oxygen, carbon and water are some of the widely known elements necessary for supporting life on Earth. Adenine, an essential organic molecule, without which the basic building blocks of life would not come together, is equally important.
But till now, scientists have not been able to find the origin of Earth's adenine and where else it might exist in the solar system.
Now, a University of Missouri-Columbia researcher has used a theoretical model to hypothesise the existence of adenine in interstellar dust clouds.

"The idea that certain molecules came from space is not outrageous. You can find large molecules in meteorites, including adenine. We know that adenine can be made elsewhere in the solar system, so why should one consider it impossible to make the building blocks somewhere in interstellar dust?" - Rainer Glaser, professor of chemistry in MU's College of Arts and Science.

Read more  (August 23, 2007)

It is our hypothesis that the DNA bases can be synthesized in the interstellar medium from the materials present in any galaxy. Hence, we think that life literally everywhere can be DNA based and, with the principle of parsimony, we believe that it is. We are studying conditions that occur, especially in our own Milky Way galaxy, to try to provide evidence for our belief.
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Blobrana


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homochirality
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In the lab, chemical reactions that synthesise amino acids and sugars create the right- and left-handed versions of the molecules in equal amounts. Life on Earth, however, uses one version almost exclusively, preferring what are conventionally called right-handed sugars and left-handed amino acids. A molecular preference for only one handedness is what chemists call homochirality.
In principle, organisms could exist that use both kinds of molecules or that exclusively adopt the opposite forms from those used in life on Earth.

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Blobrana


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RE: Ingredients for life
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The nebula RCW49 is a nursery for newborn stars and exists in circumstellar space, where chemistry is done for the very first time.
NASA/JPL-Caltech/E.Churchwell (U. of Wisconsin
The nebula RCW49 is a nursery for newborn stars and exists in circumstellar space, where chemistry is done for the very first time.



-- Edited by Blobrana at 15:45, 2007-08-01

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Blobrana


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Picture a cool place, teeming with a multitude of hot bodies twirling about in rapidly changing formations of singles and couples, partners and groups, constantly dissolving and reforming.
If you were thinking of the dance floor in a modern nightclub, think again.
It's a description of the shells around dying stars, the place where newly formed elements make compounds and life takes off, said Katharina Lodders, Ph.D., research associate professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis.

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Blobrana


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N132D: A Supernova's Shockwaves
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N132D
Credit: X-ray: NASA/SAO/CXC; Infrared: NASA/JPL-Caltech/A. Tappe & J. Rho
JPEG (410.1 kb) Tiff (2.9 MB) PS ( bytes)

Supernovas are the explosive deaths of the Universe's most massive stars. In death, these objects blast powerful waves into the cosmos, destroying much of the dust surrounding them.
This composite from NASA's Spitzer Space Telescope and Chandra X-ray Observatory show the remnant of such an explosion, known as N132D, and the environment it is expanding into.

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Blobrana


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Polycyclic aromatic hydrocarbons
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Astronomers suspect the early Earth was a very harsh place. Temperatures were extreme, and the planet was constantly bombarded by cosmic debris. Many scientists believe that life's starting materials, or building blocks, must have been very resilient to have survived this tumultuous environment.
Now, NASA's Spitzer Space Telescope has learned, for the first time, that organic molecules believed to be among life's building blocks, called polycyclic aromatic hydrocarbons (PAHs), can survive another type of harsh setting, an explosion called a supernova. Supernovae are the violent deaths of the most massive stars. In death, these volatile objects blast tons of energetic waves into the cosmos, destroying much of the dust surrounding them.

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Blobrana


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RE: Ingredients for life
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A Frankensteinesque contraption of glass bulbs and crackling electrodes has produced yet another revelation about the origin of life.
The results suggest that Earth's early atmosphere could have produced chemicals necessary for lifecontradicting the view that life's building blocks had to come from comets and meteors.

"Maybe we're over-optimistic, but I think this is a paradigm shift" - chemist Jeffrey Bada, whose team performed the experiment at the Scripps Institution of Oceanography in La Jolla, California.

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Blobrana


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Eat isotopes to live longer
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Food containing heavy isotopes of hydrogen, carbon and nitrogen could slow down the aging process. That's the claim of Oxford-based researcher Mikhail Shchepinov, who suggests that seeding key biological molecules with deuterium or carbon-13 could drastically reduce oxidative damage or even avert it altogether.
Reactive oxygen species (ROS) are a staple of ageing research, as they are believed to cause cumulative damage to biomolecules such as DNA, proteins, and lipids. Typically, breaking a carbon-hydrogen bond is the rate-limiting step of these reactions. But if the carbon or hydrogen atoms involved were replaced

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