Abiogenesis is a working hypothesis, it is currently our best idea as to how life originated given the current evidence. Some say it contradicts the "law(very loosely named)" of biogenesis, but it doesn't. Biogenesis disproves the archaic idea that full formed modern lifeforms like maggots and and mice magically arise from inanimate matter like rotting corpses and dirty laundry. By contrast abiogenesis suggest that early life arose from complex chemical reactions and self replicating molecular compounds and structures. But is there any evidence for such an event? Yes:
__________________________________________________________________
Early Earth Chemistry:
__________________________________________________________________
- On the early chemical history of the Earth and the origin of life. By Harold C. Urey
- Physical conditions on the early Earth
- Analysis of early atmosphere chemistry from zircon crystals.
What we have observed:
__________________________________________________________________
- Glycolaldehyde, a sugar which is used to form RNA, forms naturally in space 1
- That 52 amino acids, 8 of which are found in terrestrial proteins, are found in Carbonaceous chondritesiron rich metionrites
- And that large organic macromolecular compounds can be found in comets 2 3
- That peptide bonds between amino acids form at the air–water interface
- That lipid bilayers are capable of spontaneous formation
- The chemicals needed for two of life's metabolic pathways are found near hydrothermal vents
- Delicate organic molecules found on the dwarf planet Ceres probably formed there
- 1 Detection of the simplest sugar, glycolaldehyde, in a solar-type protostar with ALMA
- 2 16 organic compounds including four compounds that have never before been detected in comets found on Comet 67P/ChuryumovÂ-Gerasimenko
- 3 Rosetta probe finds amino acid glycine and phosphorus on Comet 67P/ChuryumovÂ-Gerasimenko
Experimental Data:
__________________________________________________________________
RNA:
- Ribonucleotides can form abiotically
- Conditions like meteorite impacts can generate the four nucleobases adenine, guanine, cytosine and uracil
- Pyranosyl-RNA can self assemble
- RNA like molecules can self assemble
- Precursors of ribonucleotides, amino acids and lipids from a possible abiotic origin
- Spontaneous Formation of RNA Strands, Peptidyl RNA, and Cofactors
- The replication of RNA and the expression of functional RNA can be accomplished with RNA alone
- Researchers synthesized RNA enzymes that can replicate themselves without the help of any proteins or other cellular components
- Thioester peptide nucleic acids {tPNAs} self-pair with complementary tPNA strands and cross-pair with RNA and DNA Summery article from Wired
- Methyl-RNA: an evolutionary bridge between RNA and DNA?
- Mimicking an impact on Earth’s early atmosphere yields all 4 RNA bases
- NASA finds ice sample containing pyrimidine exposed to ultraviolet radiation under space-like conditions produces uracil, cytosine, and thymine, three key components of RNA and DNA
- For the first time experiment shows that RNA can form in alkaline hydrothermal chimneys
- 22 amino acids synthesized under abiotic conditions
- Fatty acids, amines and an amino acid called glycine formed in conditions similar to meteorite impact
Proteins:
- DNA, amino acids, and ribosomes used to manufacture proteins without using cells
- Protein like amino acid chains called Proteinoids form abiotically
- Fatty molecules POPC added to solution caused unlikely self-organization and production of proteins
Chemical Evolution: __________________________________________________________________
Homochirality and Abiogenesis:
_________________________________________________________________
- Effect of polarized electromagnetic radiation on proteic amino acid
- Synthesis and chirality of amino acids under interstellar conditions
- Asymmetric autocatalysis and its implications for the origin of homochirality
- Evolution of Solid Phase Homochirality for a Proteinogenic Amino Acid
- A Possible Path to the RNA World: Enantioselective and Diastereoselective Purification of Ribose
- The Origin of Biological Homochirality
- Chiral recognition and selection during the self-assembly process of protein-mimic macroanions
The physics of entropy and abiogenesis:
__________________________________________________________________
- Entropy helps to shape protein Integrin αIIbβ3
- Entropy causes genome to self organize
- Entropy-driven stacking of plant photosynthetic membranes
- Thermodynamics might drive abiogenesis
- Computer simulations offer support for thermodynamics driven chemical evolution
Genetic "code" and formation:
__________________________________________________________________
- Proto-genes and de novo gene birth
- New genes from non-coding sequence
- Structural Insights into the Origins of DNA Polymerase Fidelity
Also of interest:
__________________________________________________________________
- "Chemically active� droplets grow to the size of cells and spontaneously divide
- The Origins of the RNA World
- The RNA Worlds in Context
- Papers from the Szostak Lab
- Evolution of biological information
- The origin of ion-pumping proteins could explain how life began in, and escaped from, undersea thermal vents.
- The Otto Research Group publications on chemistry and biology
