Chapter 26

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Synthesis of Organic Compounds on Early Earth
Early Earth's atmosphere consisted of water vapour, nitrogen, methane, carbon dioxide, ammonia, hydrogen and hydrogen sulphide.
Oparin-Haldane hypothesis
That the early Earth had a reducing environment, and that organic molecules could have formed spontaneously in such an environment.
Miller-Urey experiment
Created conditions similar that that of early Earth, to test the Oparin-Haldane hypothesis, and amino acids + hydrocarbons found in organisms today were formed.
Extraterrestrial Hypothesis
Earth was seeded with life form another planet, and that life didn't originate here.
Life Requirements (simplified)
Accurate replication and metabolism. Both are necessary for each other. IE DNA makes proteins to do stuff + replicate DNA, which creates proteins to do stuff + replicate DNA. Chicken or egg scenario.
Protobionts
Aggregates of abiotically produced molecules surrounded by a membrane or membrane-like structure. Hypothetical intermediate between the building-block molecules of life and prokaryote cells.
Ribozymes
RNA capable of catalysing.
Radiometric dating
dating based on the half-life of a radioactive isotope. Half-life is independent of everything else.
Magnetic reversals
The magnetic alignment in a rock core sample, and how it changes, allows scientists to date that way because the magnetic poles of the earth have reversed many times in the past.
Stromatolites
rocklike structures composed of many layers of bacteria and sediment. Existed some 3.5 billion years ago, and still exist today.
cyanobacteria
photosynthetic prokaryotes, caused the first major increase in oxygen levels.
Steps of eukaryotic evolution through serial endosymbiosis
Prokaryotic cell's membrane folds inwards to increase surface area, nucleus develops + Endoplasmic reticulum from the infolding. Mitochondria (aerobic heterotrophic prokaryote) is engulfed. Then, if it is a plant, Plastid (photosynthetic prokaryote) is engulfed too.
Genetic annealing
Process of gaining organelles through engulfing. "You are what you eat"
Serial endosymbiosis
series of endosymbiotic events. IE something engulfs something else and it helps both parties. (endocytosis)
Colonies
First multicellular organisms, just collections of autonomously replicating cells. Some cells in these became specialised to help the group as a whole, and as such multicellular organisms began to develop.
Cambrian explosion
Explosion in number of animal phyla.
Pangea
Original supercontinent, through continental drift the continents diverged from each other.
Three-domain system
Eukarya, Protista and Archea.
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