Course review
Review each learning objective in this topic, then open its concept explanation or question set.
Learning objective
• 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
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Learning objective
• 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
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Learning objective
• 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
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Learning objective
• 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
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Learning objective
• 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
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Learning objective
• 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
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Learning objective
• 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
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Learning objective
• 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
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Learning objective
• 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
Start with the concept explanation, then practise to create mastery evidence.