Bio 111 Cell Communication

why do cells need to communicate

-sense information from the environment

-cells interacting/coordinating for a task

-changes in transcription

-changes in enzyme activity

-uptake molecules from the environment

four essential elements in cell communication

1) signaling cell

2) ligands/signaling molecules

3) receptor cell

4) target/responding cell

signaling cell

distributes information

ligands

message

receptor cell

binds to specific ligands and receives message

target/responding cell

receives message and does something with it

types of signaling

1) endocrine

2) paracrine

3) autocrine

4) juxtacrine

how are signal types classified

by distance and ligand

which signaling types require the signaling cell to secrete an extracellular ligand

endocrine, paracrine, autocrine

which signaling types require the ligand to diffuse a short distance

paracrine and autocrine

which signaling types require the ligand to travel in the bloodstream

endocrine

which signaling types require the ligand to travel in the bloodstream

endocrine

which signaling types use a membrane attached ligand

juxtacrine

in which signaling types is the responding cell the signaling cell

autocrine

endocrine signaling

the signals travel long distances through blood or lymph to reach a responding cell

target cells in a different organ, so are released by glands

think of endocronologist (work with pancreas gland)

paracrine signaling

two cells are close so signals travel short distances

for example, they would be in the same tissue

autocrine signaling

signaling and responding cell are the same

talking to itself

juxtacrine signaling

ligand must be transmembrane on surface of signaling cell

contact dependent signaling, so cells must be touching

useful for forming borders between two tissue types

steps to cell signaling

1) receptor activation

2) signal transduction

3) response

4) termination

receptor activation

ligand is bound by receptor and receptor is activated

signal transduction

receptor is at cell’s surface and we need a way for info to get into cell so we transmit info into the cell and then amplify the signal to get a robust respnse

amplificator

don’t want to activate one single enzyme molecule, we need to increase response at multiple levels to get a big answer in the cell

response

cell does something

depends on the cell and the signal (ex: activate an enzyme, change whether or not a gene is on/off, cell division, et cetera

termination

cell stops responding

bc of cell needs and environmental changes so it is prepared to receive new info and doesn’t excessively respond