What does chemotaxis mean?
Chemotaxis is the directed movement of a cell or organism in response to a chemical stimulus in its environment, typically along a concentration gradient. Movement toward higher concentrations of the attracting substance is called positive chemotaxis, while movement away from a repellent is negative chemotaxis. The phenomenon is fundamental to biology: bacteria use it to find nutrients, immune cells such as neutrophils use it to locate sites of infection, and sperm rely on it to reach the egg. Chemotaxis is studied intensively in microbiology, immunology, and cancer research, since tumor cells can hijack chemotactic signaling to spread through the body. The word derives from Greek roots meaning "chemical arrangement" or "chemical movement" and entered English in the late nineteenth century alongside early advances in bacteriology. Though technical in register, chemotaxis is essential vocabulary for anyone reading modern biological science.
nounThe movement of a cell or organism toward or away from a chemical stimulus in its environment.
- Movement of a motile cell or organism in a direction determined by a chemical gradient, either toward (positive chemotaxis) or away from (negative chemotaxis) the source.
- By extension, any directed movement or migration influenced by chemical signals, as used metaphorically in describing cells in immunology, developmental biology, and cancer research.
"White blood cells use chemotaxis to home in on the site of an infection."
"Sperm cells exhibit chemotaxis, following chemical cues released by the egg."
"Researchers studied how cancer cells exploit chemotaxis to metastasize to distant organs."
Rarely used; chemotaxis is normally treated as an uncountable mass noun. A plural appears only when referring to distinct types or instances of the phenomenon across different organisms or contexts.
"Different bacterial species display chemotaxes tailored to their specific ecological niches."
When bacteria like E. coli chase food, they aren't smelling it — they're swimming up an invisible chemical gradient, one of nature's oldest navigation systems.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of chemotaxis
Chemotaxis combines the Greek-derived prefix chemo- (from chēmeia, relating to chemistry) with -taxis (from taxis, meaning "arrangement" or "order"). The term was coined in the late nineteenth century by German biologists during the golden age of bacteriology; it parallels other scientific compounds built on -taxis such as phototaxis. Related words sharing these roots include taxonomy and chemotherapy.
Related word forms
How chemotaxis is actually used
Chemotaxis is a technical term found almost exclusively in scientific writing, particularly microbiology, immunology, and cell biology. It is uncountable in most contexts; when a plural is needed it refers to distinct types or instances of the phenomenon. The direction of movement is specified by modifiers: positive chemotaxis (toward the chemical) and negative chemotaxis (away from it).
Easily confused with chemotaxis
Chemotropism is growth (of plants or fungi) toward or away from a chemical, whereas chemotaxis is active movement of a cell or organism.