Abundance Distribution of Compounds: Fatty Acids

The detection of a distribution of chain lengths of fatty acids is a biosignature of present and/or past life.

Created at: 
2019-05-02
Updated at: 
2021-10-25
Curator: 
Niki Parenteau
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Definition
PRO
CON

Fatty acids with a characteristic distribution of chain lengths that roughly span 30 Å (~C10 - 20) form stable membrane bilayers functional for life. [General]

Environments
Mars: Surface, Mars: Subsurface, Ocean Worlds: Enceladus Surface, Ocean Worlds: Enceladus Subsurface, Ocean Worlds: Europa Surface, Ocean Worlds: Europa Subsurface, Ocean Worlds: Titan Surface, Ocean Worlds: Titan Subsurface
eLipid headgroup-specific acyl chain remodeling is a mechanism for fine-tuning the membrane’s physical state

 

Membranes can be formed from amphiphilic biomolecules other than normal-chain fatty acids (e.g., isoprenoid lipids, peptides, other biomolecules). [General]

Environments
Mars: Surface, Mars: Subsurface, Ocean Worlds: Enceladus Surface, Ocean Worlds: Enceladus Subsurface, Ocean Worlds: Europa Surface, Ocean Worlds: Europa Subsurface, Ocean Worlds: Titan Surface, Ocean Worlds: Titan Subsurface
eMembrane bilayers in Archaea are composed of isoprenoid lipids

eShort peptides form structural and functional bilayer membranes.

Definition
PRO
CON

Bacteria (containing fatty acid membranes) are the second-most abundant pool of biotic organic carbon on the modern Earth. [Production]

Environments
Mars: Surface, Mars: Subsurface, Ocean Worlds: Enceladus Surface, Ocean Worlds: Enceladus Subsurface, Ocean Worlds: Europa Surface, Ocean Worlds: Europa Subsurface, Ocean Worlds: Titan Subsurface
eThe second major biomass component on Earth is bacteria (≈70 Gt), constituting ≈15% of the global biomass.

 

Fatty acids are rapidly degraded in the environment. [Survivability]

Environments
Mars: Surface, Mars: Subsurface, Ocean Worlds: Enceladus Surface, Ocean Worlds: Enceladus Subsurface, Ocean Worlds: Europa Surface, Ocean Worlds: Europa Subsurface, Ocean Worlds: Titan Subsurface
eIntact polar lipids containing fatty acids are rapidly degraded after cell death by the cell’s own lytic enzymes or those of decomposers (heterotrophs).

Definition
PRO
CON

Fatty acids can be produced abiotically in meteorites, IDPs, comets and other bodies. [General]

Environments
Mars: Surface, Mars: Subsurface, Ocean Worlds: Enceladus Surface, Ocean Worlds: Enceladus Subsurface, Ocean Worlds: Europa Surface, Ocean Worlds: Europa Subsurface, Ocean Worlds: Titan Subsurface
eThe distribution of chain lengths of carboxylic acids in the Murchison meteorite has not been fully characterized and may overlap biotic chain lengths and patterns.

eThe carboxylic acid compound group comprises significantly more molecular species than those unequivocally identified in the Tagish Lake and Murchison meteorites.

 

The patterns of abiotic carboxylic acid chain lengths are distinct from biotic patterns. [General]

Environments
Mars: Surface, Mars: Subsurface, Ocean Worlds: Enceladus Surface, Ocean Worlds: Enceladus Subsurface, Ocean Worlds: Europa Surface, Ocean Worlds: Europa Subsurface, Ocean Worlds: Titan Subsurface
eAbiotic Fischer-Tropsch synthesis produces fatty acids with a Poisson-like distribution in their carbon chain length number.

Membrane bilayers may be formed from abiotically synthesized amphiphilic compounds other than fatty acids. [General]

Environments
Mars: Surface, Mars: Subsurface, Ocean Worlds: Enceladus Surface, Ocean Worlds: Enceladus Subsurface, Ocean Worlds: Europa Surface, Ocean Worlds: Europa Subsurface, Ocean Worlds: Titan Subsurface
eCarboxylic acids and other amphiphilic compounds in carbonaceous chondrites are capable of forming membrane bilayers that may mimic life.

eAmphiphilic oxidized polycyclic aromatic hydrocarbons (PAH) derivatives in a simulated prebiotic membrane exhibit cholesterol-like stabilizing effect.

 
Definition
PRO
CON

Carboxylic acids are present in many meteorites and delivered in abundance to many planetary body surfaces. [Production]

Environments
Mars: Surface, Mars: Subsurface, Ocean Worlds: Enceladus Surface, Ocean Worlds: Enceladus Subsurface, Ocean Worlds: Europa Surface, Ocean Worlds: Europa Subsurface, Ocean Worlds: Titan Subsurface
eDue to the low weathering rate on Mars, significant accumulations of meteorites per square kilometer are possible.

eIntact carbonaceous chondrites on the surface of the planet may also preserve organic compounds from degradation by ultraviolet radiation.

 

Reactive oxidants in Martian soils destroy organic compounds [Survivability]

Environments
Mars: Surface, Mars: Subsurface, Ocean Worlds: Enceladus Surface, Ocean Worlds: Enceladus Subsurface, Ocean Worlds: Europa Surface, Ocean Worlds: Europa Subsurface, Ocean Worlds: Titan Subsurface
eIrradiation of perchlorate on the Martian surface produces reactive intermediates that destroy organics