Lecture notes for Friday, February 23, part one
A Digression on Chemotaxis
Accumulation of cells in a specific place can be either by selective adhesiveness ("haptotaxis") or by chemotaxis.Scientists tend to think of chemotaxis as ONE mechanism, But bacterial chemotaxis is by an increase in random turning when the attractant concentration decreases.
Leucocyte & Dictyostelium chemotaxis is by turning of locomotion toward the side where there is a higher concentration of attractant.
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video of Dictyostelium amoebae aggregating to form slugs
video of small ciliates responding to a dying larger ciliate
Two videos of computer simulations of mechanisms of chemotaxis. These were shown in class with the sound turned off, but please watch them again and listen to the recorded audio.
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first video: demonstration of behavioral rules that can produce the effects of chemotaxis
second video: user's choice of different rules