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Biology: Cell Communication
Signaling transduction pathway:
Cell Signal --> cellular response
(Series of steps in the process when signal on cell's membrane is converted into cellular response.)
Ligand-- Signaling molecule
~~~~~~~~~~~~~~~~~~~~~~~~~~
Types of signaling:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Cell-Cell
Recognition:
communication via direct contact between membrane bound cell surface
molecules. (Animal and plant
cells have junctions in cell membranes allowing cytosol dissolved signaling
substances pass freely through adjacent cells)
Local Regulators: travel short
distances only. Influence surrounding cells.
Growth Factors: Belong to Local
Regulators--stimulate growth and multiplication in nearby target cells.
~~~~~~~~~~~~~~~
Paracrine Signaling:
In animal cells only--a single cell producing
growth factor, causing numerous cells (simultaneously) to receive and
respond. ~~~~~~~~~~~~~~~~~~~
Synaptic Signaling:
Only occurs in nervous systems.
Electrical signal triggers secretion of
chemical signal (in the form of neurotransmitter molecules), diffuse across
synapse. It stimulates one target
cell. ~~~~~~~~~~~~~~~~~~~~
Endocrine Signaling:
Use of hormones for long-distance signaling.
Occurs in Plant and animal cells.
Specialized cells secret hormones into
circulatory system, and hormones are picked up by target cells.
Plant hormones are often called growth
regulators, sometimes move through cells or by diffusion as a gas to its
target cells. (e.g. ethylene, a gas, can move through cell
walls, promotes fruit ripening)
(c) copyright Susanna Shiu & Queenie Liew, since September 2007