BIOL 2200 Lecture Notes - Lecture 8: Purple Bacteria, Stromatolite, Mitosis
4 Feb 2017
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Document Summary
Geologic record is established through the strata in earth. Earth is approximately 4. 5 billion years old. Fossil record goes back 3. 5 billion years. Only starts to become diverse 535 million years ago (cambrian period) If the earth"s history is represented by a clock, the genus homo represents less than one minute. The solar system originated 4. 6 billion years ago. Oldest prokaryotic cells are 3. 5 billion years old. Oldest eukaryotic cells are 1. 8 billion years old. Oldest multicellular eukaryotes are 1. 2 billion years old. Cambrian explosion is 540 million years old. Probably predates life on earth (no fossils from this era) Earth became differentiated into the mantle, crust, and core. The atmosphere began to form from volcanic gases. Water vapor began to condense to form acidic lakes. Oxygen began to increase in the atmosphere. Stromatolites = mats of cyanobacteria living on sea surface covered with sediment. Date to 3. 5 bya but there are living examples.
