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Origin of Life: Physical Properties of Prebiotic Membrane Candidates

Roumans, Sanne (2021) MOBN02 20211
Degree Projects in Molecular Biology
Popular Abstract
Physical Properties of Prebiotic Membranes

One of the most fundamental questions in science that remains unanswered today is the question of the origin of life on Earth. Life is defined as a chemical system with the capacity of self-replication and undergoing Darwinian evolution. Origin of life research focuses on the transition of physics and chemistry to such a chemical system.

For life to arise from such a chemical system, three things are necessary: information-storing molecules capable of replication, boundary-forming molecules containing the system, and enzyme-like catalysts driving the necessary chemical reactions. RNA has been proposed as the information-storing molecule, short-chain fatty acids have been proposed as a method... (More)
Physical Properties of Prebiotic Membranes

One of the most fundamental questions in science that remains unanswered today is the question of the origin of life on Earth. Life is defined as a chemical system with the capacity of self-replication and undergoing Darwinian evolution. Origin of life research focuses on the transition of physics and chemistry to such a chemical system.

For life to arise from such a chemical system, three things are necessary: information-storing molecules capable of replication, boundary-forming molecules containing the system, and enzyme-like catalysts driving the necessary chemical reactions. RNA has been proposed as the information-storing molecule, short-chain fatty acids have been proposed as a method of compartmentalisation, and proposed catalysts include geothermal activity and the presence of salts.

In this thesis, we focused on the ability of short-chain fatty acids to form stable membranes. Research has been done on the formation of membranes from longer-chain fatty acids and other amphiphiles, but there is not a lot of information out there on the properties of membranes formed by short-chain fatty acids.

We studied the properties of the short-chain fatty acids – lauric acid (C12) and myristic acid (C14) – in aqueous solution and on solid supports and compared them to their phospholipid counterparts – DLPC and DMPC. Dynamic light scattering was used to determine the size of macromolecular assemblies in solution. We used epifluorescence microscopy to visualize the solid-supported membranes. X-ray diffraction was used to characterise the orientation of the solid-supported membranes. Finally, Molecular Dynamics simulations were used to study the behaviour of the different lipids under different conditions.

We found that phospholipids form stable vesicles in solution, whereas fatty acids do not. When prepared in a solution containing salts, the solid-supported membranes of fatty acids showed defects. Phospholipid membranes did not show defects and showed increased membrane growth. Lauric acid and myristic acid formed micelles and multi-lamellar membranes on a solid support, as seen by X-ray diffraction. The carbon tails in the myristic acid membranes were tilted. DLPC formed multi-lamellar membranes and the addition of tRNA led to intercalation of tRNA within the interlamellar spacing. This resulted in bending of the DLPC membrane. Molecular Dynamics simulations showed that lauric acid and myristic acid did not form stable structures in aqueous conditions. The fatty acids also did not interact with tRNA. DLPC and DMPC formed stable membranes in aqueous conditions and interacted with tRNA.

Our findings suggest that short-chain fatty acids are not capable of forming stable membranes which are necessary for the formation of cells. Longer carbon chains and stronger head group interactions are needed to form stable membranes. Thus, our results may affect the field of origins of life research as it changes the approach of the formation of protocells.

Master’s Degree Project in Molecular Biology 45 Credits 2021
Department of Biology, Lund University

Advisor: Maikel Rheinstädter
Origins Institute, McMaster University, Hamilton, ON, Canada (Less)
Please use this url to cite or link to this publication:
author
Roumans, Sanne
supervisor
organization
course
MOBN02 20211
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
9067622
date added to LUP
2021-11-05 11:40:19
date last changed
2021-11-05 11:40:19
@misc{9067622,
  author       = {{Roumans, Sanne}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Origin of Life: Physical Properties of Prebiotic Membrane Candidates}},
  year         = {{2021}},
}