This page has been doing the rounds on some of the computer tech blogs and social media and I wanted to share it here.
It’s a pretty deep technical dive into how E. coli chemotaxis works.
The Baffling Intelligence of a Single Cell: The story of E. coli chemotaxis
Hi Mark
This is, indeed, a fascinating paper, even though it’s often difficult to follow (for me, anyway). But the basic molecular process that allows E. coli to successfully navigate to an attractant via a biased random walk is pretty clear and the molecular/mechanical details of the structure and mechanism of the motor that drives the flagella that propel the bacterium are amazing to see. What we have here is a control system that is implemented via molecules rather than neurons. It would be an interesting exercise to map out this molecular control process in terms of the main functional components of a control system: sensor, comparator, reference, error, output, feedback function.
One thing I didn’t understand is how the adaptation process works that increases the dynamic range of the attractant sensor. It seems to me that this adaptation process might be functionally equivalent to a second level control system that keeps the sensor reaction range appropriate to the range of the attractant concentration through which E. coli is moving. If you understand how this adaptation mechanism works could you please explain it and, even better, describe the code that would allow a simulation of E. coli which can move to a nutrients that are surrounded by attractant gradients that vary in density by several orders of magnitude.
Very interesting stuff. It’s amazing how much is known about the details of the E. coli navigation process.