BIOL 2P05 Lecture Notes - Lecture 21: Quorum Sensing, Multicellular Organism, Cyclic Adenosine Monophosphate
14 Mar 2018
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Document Summary
Transition from single-celled to multi-celled organisms has occureed independently many times. Once resources are limited, they aggregate to form a multicellular slug. Slime molds as examples of coming together multi-cellularity. Quorum sensing: ability of other cells to sense chemicals released by other cells. Once they arrive, they produce sticky" proteins causing them to aggregate. A signalling system conveys directional and gradient information. Camp signalling system allows the slig to orient to ambient environmental clues (ex. Slug can sense and respond to environmental cues more efficiently than individual cells. Sheath around the slug can protectit from nematode predators. Surface/area ration makes a slug sheth less expensive than in an individual. Once it reaches the surface, slug breaks apart into smaller fruiting bodies. Stalk and spore cells are more genetically similar. Natural selection facilitates transitions from one level of individuality to another by the same incremental improementsthat darwin proposed for the evolution of complex traits.
