Cells can move by pushing cytoplasm forward {amoeboid motion}|.
Vertebrate cells can have membrane protuberances {cilia}| {cilium} one-hundredth to one-thousandth cell diameter. At cilia bases, bodies {basal body} have nine tubules and duplicate at cell division.
Primary cilia have nine outer filaments and no central filaments. Most vertebrate cells have one primary cilium, and it does not move. Primary cilia receive signals, relay signals to cell body along tubules {intraflagellar transport}, and affect development and wound-healing. Sonic hedgehog protein binds to primary cilia and releases signal proteins that travel to nucleus. Leptin binds to hypothalamus-neuron primary cilia. Wnt binds to primary cilia to orient developing-tissue cells.
Motile cilia have nine outer filaments and two central filaments. Cells can have many or no motile cilia. Central filaments allow wave-like motion. Coordinated waves can establish clockwise or counterclockwise motion and so designate right from left, as needed to place and structure body tissues and organs.
Eye and nose receptors have modified cilia that contain receptive chemicals.
flagellum
Cilia and flagella have same organization.
Cells can move by spinning themselves {cyclosis}.
Cells can move by twisting one long hair-like membrane protuberance {flagella} {flagellum}. Cilia and flagella have same organization.
Plant and lower-animal cells can extend cell membrane around food material and then re-close membrane to make food vacuoles {pinocytosis}|.
Cells can move toward or away from stimuli {taxis}|. Single-cell organisms can move toward or away from oxygen (aerotaxis, in bacteria), molecules (chemotaxis, in bacteria and protozoa), gravity (geotaxis, in protozoa), light (phototaxis, in phytoflagellates and protozoa), and contact (thigmotaxis).
Organisms can change activity (kinesis) in response to stimulus. Organisms can grow (tropism) toward or away from stimuli.
Organisms can change activity {kinesis} in response to stimulus. For example, organisms can grow (tropism) toward or away from stimuli.
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Date Modified: 2022.0225