BI110 Chapter Notes - Chapter 74: Nuclear Membrane, Exponential Growth, Symbiogenesis
Document Summary
Earth is divided into 3 eons: archaean (first single-celled organisms appeared, protezoic (first eukaryotes and multicellular organisms appeared, phanerozoic (animals appeared; divided into paleozoic, mesozoic, and cenozoic era) Hypothesis: 1st living organisms were anaerobic archaebacterial that evolved in hydrothermal vents near submarine volcanoes; where anaerobic bacteria still live. Fossilized prokaryote communities bound very thin layers of sediment together into rocks called stromatolites: only life forms for the next 1. 5 billion years. Prokaryotes have distinct subunits that perform individual functions: prokaryotes have organized structures called micro-compartments. Micro-compartments produce energy for cellular metabolism + carry out other important processes within cell. Made of proteins and structurally resemble viruses: viruses. Oxygen makes up 21% of the atmosphere; but early atmosphere had no oxygen: oxygen levels rose b/w 2. 5 2 bya. Photosynthetic prokaryotes emerged and diversified in oceans + released more and more oxygen as a byproduct of photosynthesis. Oxygen produced by cyanobacteria remained dissolved in ocean water.
