direct contact
cell communication via direct contact; examples of this type of cell communication include plasmodesmata, gap junctions and immune cell activity
autocrine signaling
the target cell is also the secreting cell
local regulators
A chemical messenger that influences cells nearby
gap junctions
provide cytoplasmic channels between adjacent animal cells, holes in cell membranes
plasmodesmata
An open channel in the cell wall of plants through which strands of cytosol connect adjacent cells
reception
A target cell's ability to detect a signal molecule coming from outside the cell; stage 1 in cell signalling .
response
The cell's reaction to a chemical messenger.
ligand
A molecular messenger that binds to specific receptors on, or within, the cell. It is not chemically altered.
receptors
Molecules (often proteins) that detect specific ligands in their internal or external environment.
paracrine signalling
type of cell communication in which chemical messengers are detected by nearby cells
endocrine signalling
long distance signaling that uses hormones as ligands that travel through the blood
hormones
Chemical messengers manufactured endocrine glands & travel through the bloodstream to distant target cells
G-protein coupled receptors
A special class of membrane receptors with an associated GTP binding protein; this receptor involves dissociation and GTP hydrolysis
Neurotransmitters
chemical messengers that cross the synaptic gaps between neurons
ligand-gated ion channel
Type of membrane receptor that has a region that can act as a "gate" when the receptor changes shape.
transduction
The transfer of the signal from the cell membrane resulting in a change in cell activity; stage 2 in cell signalling.
phosphorylation cascade
A series of enzyme-catalyzed phosphorylation reactions commonly used in signal transduction pathways to amplify and convey a signal inward from the plasma membrane.
secondary messenger
A small, nonprotein, water-soluble molecule or ion, such as calcium ion or cyclic AMP, that relays a signal to a cell's interior in response to a signal received by a signal receptor protein.
Cofactors
Organic molecules (not proteins) that assist in the normal functioning of enzymes (Zinc)
feedback inhibition
A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.
positive feedback loop
Causes a system to change further in the same direction.
negative feedback loop
A feedback loop that causes a system to change in the opposite direction from which it is moving
Homeostasis
process by which organisms maintain a relatively stable internal environment
Kinases
Enzymes that catalyze the transfer of phosphate groups from ATP to acceptor molecules.
secondary messengers
Intermediate chemicals that help transduce a chemical signal
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