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Name 4 processes needed for the first cells to form.
- 1. Chemical reactions to produce simple organic molecules
- 2. Assembly of the above molecules into polymers
- 3. Formation of polymers that can self replicate
- 4. Development of membranes to form spherical droplets with internal chemistry different from external
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Name the guys involved in an experiment that simulated the begninnings of life on earth.
Miller and Urey
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What year did Stanley Miler and Harold Urey do their seminal experiment?
1953
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What gases did Miller and Urey include in their experiment?
Ammonia (NH3), methane (CH4), hydrogen (H2)
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Name at least 3 locations that have been sugested for the synethesis of the organic compounds needed for the origin of life.
- 1. Chemical reactions in the atmosphere and in water, on the surface of the earth
- 2. Hydrothermal vents
- 3. Extraterrestrial origin (there was a heavy bombardment of the Earth by meterorites 4000 million years ago which may have brought the organic compounds
- 4. Near volcanoes (It spews out water vapour, other gases and various minerals which could be used to form organic matter)
- 5. Alternating wet/dry conditions (Seashore or flood plains of a river where there are alternating wet/dry conditions could provide a place for catalysing reactions and forming early organic molecules).
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What is a coacervate?
Water containing membrane bound microspheres that is viscous and cloudy in appearance.
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What is a protobiont?
Primitive cell like structures, that may have preceded living cells.
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Outline 2 properties of RNA that would have allowed it to play a role in the origin of life
RNAs can store, transmit and replicate genetic information
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Outline the contribution of prokaryotes to the creation of an oxygen-rich atmosphere
- 1. Around 2 billion years ago a form of chlorophyll appeared in bacteria that allowed photosynthesis
- 2. The oxygen content rose to 0.45%. This coincides with the rise of the Eukaryotes
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What is the endosymbiotic theory?
The theory that chloroplasts and mitochondria were once free-living prokaryotes that were engulfed by larger prokaryotes. These then evolved into organelles of eukaryotes.
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What is the evidence for the endosymbiotic theory?
Characteristics of mitochondria and chloropasts support endosymbiotic theory.
- *Both grow and divide like cells
- *Have a naked loop of DNA (like prokaryotes)
- *Synthesize some of own proteins using 70S ribosomes, like prokaryotes
- *Have double membranes (as expected when cells are taken into a vesicle by endocytosis)
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