cellular communication

direct contact communication

communication through cell junctions between touching, adjacent cells

gap junctions

provide cytoplasmic channels between adjacent animal cells; are used for direct contact communication

plasmodesmata

An open channel in the cell wall of plants through which strands of cytosol connect from adjacent cells; used for direct contact communication

communication utilized by immune cells

direct contact communication

local signaling

signaling between adjacent (nearby, but not touching) cells (paracrine and synaptic)

target cell

cells that have receptors for a particular hormone

paracrine signaling

cell secrete local regulators (such as growth factors) to a nearby target cell.

synaptic signaling

a type of local signaling specific to neurotransmitters in nerve cells

long distance signaling

signaling between cells separated by some distance

endocrine signaling

long distance signaling used by animals where they release hormones into the circulatory system (bloodstream) where they reach target cells

long distance signaling in plants

release hormones that travel in the plant vascular tissue (xylem and phloem) or through the air to reach target tissues

insulin signaling

an example of long distance signaling where insulin is released into the bloodstream by the pancreas

reception

first stage of cell signaling where the receptor binds to a ligand and undergoes a conformational change

ligand

chemical signal molecule that binds to the receptor

transduction

the second stage of cell signaling; conversion of an extracellular signal to an intracellular signal that will bring about a cellular response

response

the third stage of cell signaling where a cell process is altered

plasma membrane receptors

bind to water-soluble (hydrophilic) ligands; examples include G protein coupled receptors (GPCRs) and ligand-gated ion channels

g-protein coupled receptors (GPCRs)

ligand binding to GPCR will activate a particular G protein, which can bind to and activate an associated enzyme that amplifies the signal and leads to a cellular response

ligand-gated ion channel

act as a "gate" for ions, opening and closing to allow for the diffusion of specific ions

intracellular receptors

receptors located inside the target cell (usually found in the cytosol or on the nucleus) that bind to nonpolar/hydrophobic ligands

protein kinase

relays the signal of the signal transduction pathway by phosphorylating the molecules in the signal cascade

second messengers

A small, nonprotein, water-soluble molecule or ion, such as calcium ion or cyclic AMP, that help relay the message and amplify the response

protein phosphatase

the enzyme molecule that dephosphorylates molecules in the signal transduction pathway, leading to the pathway being shut off

dephosphorylation

removal of a phosphate group by the enzyme protein phosphatase, shutting off the pathway

transcription factors

regulate gene expression by turning genes on and off