[BIO315H5] - Final Exam Guide - Comprehensive Notes fot the exam (155 pages long!)
Document Summary
Quorum sensing: a system of stimuli and response correlated to population density. Many species of bacteria use quorum sensing to coordinate gene expression according to the density of their local population. Many bacteria respond to chemical signals that are secreted by their neighbors and accumulate at higher population density allows bacteria to coordinate their behaviour, including their motility, antibiotic production, spore formation, and sexual conjugation". Communication between cells in multicellular organisms is mediated mainly by extracellular signal molecules. Many of the same types of signalling (cid:373)olecules are used i(cid:374) paracri(cid:374)e, sy(cid:374)aptic, a(cid:374)d e(cid:374)docri(cid:374)e sig(cid:374)alli(cid:374)g" the crucial differe(cid:374)ces lie i(cid:374) the speed and selectivity with which the signals are delivered to their targets. Signal molecule often has different effects on different types of target cells. Ach decreases the rate of action potential firing in heart pacemaker cells, and stimulates production of saliva by salivary gland cells (even though receptors are same on both cell types)
