The use of amino acids for life detection in the solar system

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Title: The use of amino acids for life detection in the solar system
Authors: Chan, Hoi-Shan
Item Type: Thesis or dissertation
Abstract: To date, the fundamental question of how life originated remains unanswered. The main mystery that has to be solved is how prebiotic chemistry has evolved into primitive biotic chemistry. The primitive record of biological evolution is no longer preserved on Earth due to destructive tectonic processes. However, examples of the organic inventory of the early solar system are available in carbonaceous chondrites. The varied organic content of these meteorites could have provided an exogenous source of organic molecules for the onset of life on the early Earth. My research examines the amino acid contents of carbonaceous and ordinary chondrites analysed with gas chromatography–mass spectrometry (GC-MS). The enantiomeric (D/L) ratios of amino acids were obtained to distinguish materials produced biotically or abiotically as life on Earth is dominated by L-asymmetry. This study reveals that the ordinary chondrite Chainpur contains abundant amino acids. Despite the D/L ratios indicating a certain level of terrestrial contamination, the presence of non-protein amino acid suggests the presence of indigenous materials in the meteorites. Once arisen, life was undoubtedly successful on Earth. But it may have also existed on Mars. This hypothesis will be tested by forthcoming life-detection missions that will carry out in situ analyses on the Red Planet. Fluorescence spectroscopy is a technique that targets biologically significant organic molecules such as amino acids. These molecules are important building blocks of life. The focus of this research is to analyse the fluorescence patterns of a range of standards representing terrestrial and extraterrestrial amino acids and their mixtures, alongside a Martian soil analogue, Salten Skov. This study identifies the optimal excitation and emission wavelengths for amino acids and evaluates the problems associated with photochemical quenching. Spectrofluorometry is a quick and simple analytical technique that offers high sensitivity and immediate identification. Overall, this study aids in understanding the organic reservoir that may have contributed to the origin of life and provides imperative information for successful life-detection missions.
Issue Date: Nov-2011
Date Awarded: May-2012
URI: http://hdl.handle.net/10044/1/9662
Supervisor: Martins, Zita
Sephton, Mark
Genge, Matthew
Sponsor/Funder: Science and Technology Facilities Council (Great Britain) ; Royal Society (Great Britain) ; Imperial College London ; University of Hong Kong
Department: Earth Science and Engineering
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Earth Science and Engineering PhD theses



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