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Unformatted text preview: Chapter 11 11.1 – External signals are converted to responses within the cell- There are two sexes, or mating types, called a and α.- Cells of mating type a secrete a signaling molecule called factor, which can bind to specific receptor proteins on nearby α cells.- At the same time, α cells secrete α factor, which binds to receptors on a cells.- Once received at the yeast cell surface, the mating signal is changed, or transduced , into a form that brings bout the cellular response of mating. The received signal is converted to a specific cellular response in a series of steps called a signal transduction pathway.- Scientists think that signaling mechanisms first evolved in ancient prokaryotes and single-celled eukaryotes, then were adopted for new uses by their multicellular descendants.- The concentration of such signaling molecules, sensed by the bacteria, allows them to monitor the local density of cells, a phenomenon called quorum sensing. Quorum sensing allows bacterial populations to coordinate their behaviors so they can carry out activities that are only productive when performed by a given number of cells in synchrony.- Biofilm – an aggregation of bacterial cells adhered to a surface; the cells in biofilm generally derive nutrition from the surface they are on....
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- Winter '12
- Cell Signaling, cells, cellular response