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Origin of Life (2)
USC FSH BISC121 M2 Fuhrman
| Term / Question | Definition / Answer |
|---|---|
| Stromatolites | Fossilized layered microbial mats that was a rich source for early prokaryote fossils |
| When did prokaryotes dominate evolutionary history? | ~3.5 to 2.0 billion years ago |
| When are the oldest fossils recovered from? | Fossils resembling bacteria that were embedded in rocks from western Australia from 3.5 billion years ago |
| When did the Earth begin to cool to a temperature at which liquid water could exist? | ~ 3.9 billion years ago |
| When did the Earth form? | ~4.5 billion years ago |
| When were the oldest surviving rocks on Earth? | ~3.8 billion years ago |
| How were the organisms in the first three-quarters of evolutionary history? | Microscopic and mostly unicellular |
| What are the two rich sources for early prokaryote fossils? | Stromatolites and sediments from ancient hydrothermal vent habitats |
| When did oxygen begin accumulating in the Earth's atmosphere? | ~2.7 billion years ago |
| What does photosynthesis require? | A source of available hydrogen atoms that provide reducing power, allowing carbon dioxide to be reduced to make organic carbon |
| When did cyanobacteria evolve? | over 2.7 billion years ago |
| What was the role of cyanobacteria in early evolution? | A photosynthetic organism that split water and produced oxygen as a byproduct, due to the ready availability of water |
| What are banded iron formations? | Precipitate iron oxide produced by the initial reaction of early oxygen with dissolved iron |
| How was the oxygen accumulation in early Earth's history? | Gradual between 2.7 and 2.2 billion years ago; shot up to 10% of current values shortly after |
| What was the Earth's biggest air pollution event? | When oxygen accumulation shot up, reactive and mostly toxic oxygen gas doomed many prokaryote groups |
| When did eukaryotes first appear? | ~2.1 billion years ago |
| When did multicellular eukaryotes first appear | ~1.2 billion years ago |
| What were the first unicellular eukaryotes? | Protists |
| "Snowball Earth" hypothesis | Geologic evidence suggests that a near-global ice cover from 750 to 635 million years ago may be responsible for the limited diversity and distribution of multicellular eukaryotes until the very late Pre-cambrian era |
| Pasteur experiment | 1862: conducted broth experiments that rejected the idea of spontaneous generation |
| Spontaneous generation | A early commonly accepted idea that life could arise from non-living matter (now proven false) |
| Biogenesis | The principle that all life today arises only by the reproduction of pre-existing life |
| Protobionts | The first formed cells formed by the aggregate of abiotically-synthesized organic molecules surrounded by membranes |
| Oparin-Haldane hypothesis | 1920s: postulated that conditions on the early Earth favored the synthesis of organic compounds from inorganic precursors - the abiotic synthesis of organic molecules |
| How do young suns differ from older ones? | Emit more UV radiation amid the lack of an ozone layer due to no free oxygen molecules, allowing radiation to reach earth |
| How does the reducing environment in the early atmosphere support the Oparin-Haldane hypothesis? | Lightning and the intense UV radiation that penetrated the primitive atmosphere could have provided the considerable energy required to make organic molecules |
| Miller-Urey experiment | 1953: tested Oparin-Haldane hypothesis by creating conditions that postulated early Earth in a laboratory, discharging sparks in an "atmosphere" of gases and water vapor |
| RNA World hypothesis | The idea that the first hereditary genetic material was RNA, not DNA as it is both genetic material and a functional enzyme |
| Thomas Cech | 1980: discovered that RNA molecules are important catalysts in modern cells |
| Ribozymes | Remove introns from RNA and catalyze protein synthesis |
| Liposomes | Droplets of abiotically produced organic compounds formed when lipids are mixed in; lipids form a molecular bilayer at the surface, and can undergo osmotic swelling or shrinking, and store energy as a membrane potential |
Created by:
elephantmonkey66
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