The directional movement of an organism or a living motile cell in response to certain diffusible chemicals in the environment
Chemotaxis is a response of motile cells or organisms in which the direction of movement is affected by the gradient of a diffusible substance. It differs from chemokinesis in that the gradient alters probability ofmotion in one direction only, rather than rate or frequency of random motion. There are two major types of chemotaxis: (1) positive chemotaxis, i.e. the movement is toward a higher concentration of the diffusible substance, and (2) negative chemotaxis, i.e. the movement is in the opposite direction.
Chemotaxis is a kind of taxis, in which bodily cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. This is important for bacteria to find food (for example, glucose) by swimming towards the highest concentration of food molecules, or to flee from poisons (for example, phenol).
In multicellular organisms,chemotaxis is critical to development as well as normal function. In addition, it has been recognized that mechanisms that allow chemotaxis in animals can be subverted during cancer metastasis. Certain cells release chemotactic cytokines (or chemokines) to attract motile cells such as T cells towards the direction of the chemokines.
Word origin: chemo- (of chemicals) + Ancient Greek táxis (arrangment, order)