- Primordial atmosphere + ocean + heat + lightning = amino acids
- Autocatalysis: enzyme that catalyzes the synthesis of itself
- Origin of hereditary: replication + variation = competition = selection
- Protein: any 3d shape by chemical affinities of amino acids - good at being enzymes
- DNA: double helix - good at preserving sequence, being copied, and error proofing
- RNA: lack self-pairing of complementary chain - pair with bits of itself - versatile mix of both
- 5S ribosomal RNA: smallest and simplest RNA - possibly the origin of life
- in all domains of life (bacteria, archaea, and eukaryotes, discarded by animal mitochondria)
- the ingredients of DNA are made by modifying the ingredients of RNA (T from U), not by a more direct route
- most basic/primitive functions in cells require RNA
- many protein enzymes rely on small RNAs to make them work
- only RNA can copy itself without assistance
Rerunning origin of RNA life
By repeatedly selecting random RNA molecules in the test tube based on their ability to catalyse reactions, it is possible to ‘evolve’ catalytic RNAs from scratch-almost to rerun the origin of life. And one of the most surprising results is that these synthetic RNAs often end up with a stretch of RNA text that reads remarkably like part of the text of a ribosomal RNA gene such as the 5S gene on chromosome 1.
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Protozoa-like = first organisms with DNA-protein
- Bacteria dropped RNAs when adapting to heat & niches like parasitic/scavenging
- Simplify = advantage
Hospitable zone?
Most likely to have given rise to life ≠ necessarily hospitable for most life now
The concept of a habitable zone incorporated an initial bias that room temperature is just right for life. But some organisms just love several-hundred-degree hot tubs and find room temperature downright hostile. To them, we are the extremophiles. Many places on Earth, previously presumed to be unlivable, such creatures call home: the bottom of Death Valley, the mouths of hot vents at the bottom of the ocean, and nuclear waste sites, to name just a few.
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