Carbon compounds {carbon-based life} can be soluble or insoluble and have intermediate-stability chemical bonds, so they can form and break at moderate energies.
organic molecules
Organic molecules formed in seas. Stable forms persisted. Persisting molecules aggregated.
nucleic acids
When nucleotide concentrations were great enough, nucleotides linked. Nucleic acids used themselves as templates to make copies. Good copiers persisted and used more nucleotides. Mutations resulted in populations with property ranges.
peptides
When amino-acid concentrations were great enough, amino acids linked. Peptides assisted chemical reactions and formed structures.
oxygen
Later, photosynthesis added oxygen to atmosphere, using water, sunlight, and atmosphere carbon dioxide.
Silicon compounds {silicon-based life} cannot substitute for carbon compounds, because silicon compounds are insoluble, silicon makes shorter bonds, and silicates are too stable.
In living organisms, sugars and amino acids are in only one of two possible stereochemical forms {chirality, molecule}|. Sugar and amino-acid chirality probably had survival value, but people do not yet know cause [Gardner, 1960].
Perhaps, living things or organic molecules are in cosmic dust, meteors, comets, asteroids, and planets and then travel to Earth in dust, meteors, or comets {panspermia}.
Glycerin molecules mixed with other molecules can clump together to make stable gels {coascervate}| [1926]. Other molecules can enter, interact inside, and leave.
Nucleic acid and protein can combine. Perhaps, dissolved genes in early oceans evolved to make genes with protein shells {proto-virus}. Proto-viruses can acquire lipid layers, making micelles. Proteins can embed in lipids, to make cell membranes. Food can pass from seawater into simple cells. Chemosynthesis can evolve. Simple cells can replicate. Later, photosynthesis can evolve.
Perhaps, RNAs had genetic codes, were enzymes, and formed structures {RNA world}. RNAs folded and unfolded to perform functions.
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0225