NATS 1670 Lecture 9: Lecture 9
8 Mar 2017
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Document Summary
Diversity of prokaryotes environmental conditions: water, most cells require a minimum moisture content, some bacteria can make spores: cells that survive in the near absence of water. Salt: most cells require a moderate level of salt, some cells can exist in very high salt concentrations (halophiles) Oxygen availability: require oxygen for growth aerobic, require lack of oxygen for growth anaerobic. Nutrient availability: most microorganisms require organic and inorganic nutrients to grow and survive, cyanobacteria grow in the absence of key nutrients: e. g. can convert co2 from air into organic cellular molecules. Ancient microorganisms first produced oxygen a billion years before the first plants even existed. 1. 5 billion years ago, multicellular eukaryotic cells existed. 2. 1 billion years ago was when they first started to be found. Over 4 billion years ago, there were no cells, there were a bunch of chemical reactions. Universal ancestor (the parental of all other organisms that exist today) The bacteria and archaea are mostly unicellular microbes.
