MICB 201 Study Guide - Final Guide: Quorum Sensing, Purple Bacteria, Repressor
Document Summary
Absence: motility does not result in net movement in any particular direction. Presence: net movement occurs towards the higher concentration of the nutrient. Chemotaxis can be broken down in three steps: response to signal, control of flagella rotation, adaptation. Going in the right direction: a signal sent to the fli protein, inhibiting tumbling so an average run is longer. Going in the wrong direction: a signal sent to the fli protein, stimulating tumbling so an average run is shorter. Cw: describe the classic experiments establishing that temporal sensing is part of flagellar-based chemotaxis. Added galactose and mixed it very rapidly (no gradient). If spatial sensing was used, cells would not sense anything different (no gradient) and they should display the random walk. If temporal sensing, cells would remember that the previous measurement was low, and now the measurement is high. Would behave as though in a gradient, tumbling would be inhibite d (runs longer).
