Summary
Cells bias a random walk toward attractants by controlling flagellar rotation through CheY.
In depth
Chemoreceptors (MCPs) detect attractants; CheA/CheY control motor direction. Counter-clockwise rotation bundles flagella and the cell runs; clockwise causes tumbling. Attractants reduce tumbling frequency; adaptation by methylation resets sensitivity.
Bacteria sense changes over time, not absolute concentration. Methylation of receptors gives adaptation. Chemotaxis is important for infection.
Common mistake: bacteria do not steer; they bias a random walk.
E. coli swims at about 20 body lengths per second and senses gradients by comparing concentrations over time, not along its length. When going up an attractant gradient, runs are longer, giving a biased random walk. Adaptation by methylation of receptors resets sensitivity so cells can respond to changes across a thousand-fold range of concentration.
Chemotaxis directs bacteria to nutrients and away from toxins, and enables pathogens to find hosts (Helicobacter swims toward urea in the stomach lining). Magnetotactic bacteria use magnetosomes to align with the Earth's field. Phototaxis and aerotaxis are related.
Key idea: it is a model for sensory systems, with amplification, adaptation and memory in a small network.
Frequently asked questions
What is Bacterial Chemotaxis?
Cells bias a random walk toward attractants by controlling flagellar rotation through CheY.
Which area of biology covers Bacterial Chemotaxis, and how advanced is it?
Bacterial Chemotaxis is one of the 54 topics in Microbiology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Bacterial Flagella and Pili, Two-Component Systems, Bacterial Secretion Systems.
Can you give an example of Bacterial Chemotaxis?
E. coli moves toward high glucose.
What should I learn before Bacterial Chemotaxis?
Work through the Beginner topics in Microbiology first, such as Microorganisms, Bacteria, Archaea, then return to Bacterial Chemotaxis. Advanced topics assume the Intermediate vocabulary.
What topics are related to Bacterial Chemotaxis?
The closest topics to Bacterial Chemotaxis are Bacterial Flagella and Pili, Two-Component Systems, Bacterial Secretion Systems, Protozoan Parasites. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Bacterial Chemotaxis?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Bacterial Chemotaxis. To practise the whole of Microbiology, use the Microbiology quiz.
How is Bacterial Chemotaxis different from Bacterial Flagella and Pili?
Bacterial Chemotaxis: Cells bias a random walk toward attractants by controlling flagellar rotation through CheY. Bacterial Flagella and Pili: Flagella propel cells while pili attach to surfaces and transfer DNA during conjugation. Read both side by side and note what each one explains.
What is a common mistake about Bacterial Chemotaxis?
Bacteria do not steer; they bias a random walk.
How should I study Bacterial Chemotaxis step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Bacterial Flagella and Pili and explain the difference aloud. Finally, take the Microbiology quiz and come back to this page for any question you miss.