BIOL208 Lecture 9: Origin of Life on Earth Part 1
29 Mar 2018
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Lec 9: origin of life on earth part 1. Earth"s biodiversity built on profound biochemical and genetic similarity. "life" is easy to recognize but hard to define. It is generally accepted that an entity needs to have these features to be considered alive. Organization: structurally composed of one or more cells (basic units of life) Metabolism: a system of management of energy and materials via chemical reactions. Response to stimuli: via changes in growth, alteration of chemical reactions or movement. Homeostasis: maintenance of some internal chemical and/or thermal consistency relative to variation outside of the entity. Adaptation: ability to change over a period of time in response to the environment. 3. 5 bya: first prokaryotes (single celled) and photosynthesis (cyanobacteria) 535-525 mya: cambrian explosion (great increase in diversity of animal forms) 500 mya: colonization of land by fungi, plants and animals. The phanerozoic eon contains the last half billion years, and encompasses multicellular eukaryotic life.
