The origin of cells links prebiotic environments, abiotic organic synthesis, membrane compartments, self-replicating RNA, radiometric evidence, and the shared ancestry of modern cellular life.
Coverage 2012–2025 · Updated 15 Jul 2026
• Early Earth had volcanic gases, high CO₂, methane, water vapour, and little free oxygen
• Lack of ozone allowed intense UV radiation at Earth's surface
• Prebiotic chemistry may have formed amino acids, bases, sugars, fatty acids, and nucleotides
• Cells are self-sustaining units with membranes, genetic material, and metabolism
• Life requires heredity, variation, compartmentalization, and Darwinian evolution
• Viruses contain genetic material but lack independent cellular metabolism
• First cells had to arise from non-living materials by self-assembly
• Required steps include organic synthesis, polymerization, self-replication, and membranes
• Competing hypotheses include protocell-first, gene-first, and metabolism-first models
• Miller-Urey produced amino acids from methane, ammonia, hydrogen, and water vapour
• Later experiments used different gases and energy sources, including UV and ionizing radiation
• Results support abiotic synthesis of amino acids, fatty acids, sugars, bases, and simple polymers
• Amphipathic fatty acids can spontaneously form monolayers, bilayers, and vesicles
• Microspheres could enclose polymers and monomers, creating internal chemistry
• Fatty acids likely preceded more complex phospholipid membranes
• RNA can store genetic information and fold into catalytic ribozymes
• RNA world hypothesis proposes RNA acted before DNA and protein enzymes
• Evidence includes ribosomal RNA catalysis, RNA primers, and ribose forming under prebiotic conditions
• LUCA links the abiotic phase of Earth history to all later cellular life
• Universal genetic code, shared biochemistry, and conserved genes support common ancestry
• Genomic studies found shared gene families likely inherited from LUCA
• Fossils and surrounding rocks can be dated by radiometric methods
• Molecular clocks use DNA or protein changes to estimate divergence times
• LUCA may have existed around 4 billion years ago
• Nuvvuagittuq haematite tubes provide fossil evidence from ancient hydrothermal vents
• Conserved genes suggest LUCA was anaerobic, CO₂-fixing, H₂-dependent, N₂-fixing, and thermophilic
• Hydrothermal vents supplied hydrogen, carbon dioxide, iron, heat, and chemosynthetic energy
