* Astronomy

'Primodial Soup' theory for origin of life rejected in paper

For 80 years it has been accepted that early life began in a 'primordial soup' of organic molecules before evolving out of the oceans millions of years later. Today the 'soup' theory has been over turned in a pioneering paper in BioEssays which claims it was the Earth's chemical energy, from hydrothermal vents on the ocean floor, which kick-started early life.

"Textbooks have it that life arose from organic soup and that the first cells grew by fermenting these organics to generate energy in the form of ATP. We provide a new perspective on why that old and familiar view won't work at all. We present the alternative that life arose from gases (H2, CO2, N2, and H2S) and that the energy for first life came from harnessing geochemical gradients created by mother Earth at a special kind of deep-sea hydrothermal vent -- one that is riddled with tiny interconnected compartments or pores" - team leader Dr Nick lane from University College London.

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Title: Large prebiotic molecules in space: photo-physics of acetic acid and its isomers
Authors: Fabrizio Puletti, Giuliano Malloci, Giacomo Mulas, Cesare Cecchi-Pestellini

An increasing number of large molecules have been positively identified in space. Many of these molecules are of biological interest and thus provide insight into prebiotic organic chemistry in the protoplanetary nebula. Among these molecules, acetic acid is of particular importance due to its structural proximity to glycine, the simplest amino acid. We compute electronic and vibrational properties of acetic acid and its isomers, methyl formate and glycolaldehyde, using density functional theory. From computed photo-absorption cross-sections, we obtain the corresponding photo-absorption rates for solar radiation at 1 AU and find them in good agreement with previous estimates. We also discuss glycolaldehyde diffuse emission in Sgr B2(N), as opposite to emissions from methyl formate and acetic acid that appear to be concentrate in the compact region Sgr B2(N-LMH).

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Billions of years ago, comets may have ferried life-sustaining water to our planet's surface, but that may not be all that we should thank these dirty snowballs for. Researchers are simulating comet impacts to see if they might help proliferate the left-handedness in molecules that life on Earth depends upon.
There is evidence from meteorite studies that amino acids may have been delivered to Earth from space.

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EPSC09/13: Could salt crusts be key ingredient in cooking up prebiotic molecule

German scientists investigating the complex chemical mixture thought to be present in the early Earth's oceans have found that amino acids can be 'cooked' into many other important chemical building blocks of life when embedded in salt crusts. Results of the laboratory experiments will be presented by Dr Stefan Fox at the European Planetary Science Congress in Potsdam, Germany, on Thursday September 17.
Approximately 4.5 - 3.8 billion years ago, the Earth was probably covered by a salty ocean, rich in organic compounds, dotted with active volcanic islands and short-lived continents. The team from the University of Hohenheim in Stuttgart has simulated some of the chemical processes that might have taken place along hot volcanic coasts during this Hadean era by evaporating solutions of artificial primordial seawater and then baking the salty residue in an atmosphere of nitrogen and carbon dioxide to volcanic temperatures of 350 degrees Celsius. They found that compounds such as pyrroles, which are contained in chlorophyll and haeme, are created.
The group's experiments show that interaction of amino acids with metal ions in the salt crusts fundamentally changes the thermal behaviour of the molecules, preventing them from turning into gas at high temperatures and allowing unexpected compounds to form.

"We embedded the amino acid DL-alanine in a salt crust mixture of sodium, calcium, potassium and magnesium chlorides and, after heating, we found that a compound formed with calcium salt chemically bonded to the amino acid. This particular compound has never been seen before and, although similar compounds are known to exist, we did not expect to see them in our experiments. This bond between the salt and the amino acid stabilizes the compound at high temperatures and prevents sublimation. Without the bond, pyrroles would not be able to form" - Dr Stefan Fox .

Source: European Planetology Network

-- Edited by Blobrana on Thursday 17th of September 2009 03:31:48 PM