Cell signalling 1 Flashcards
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Where are cell surface receptors found?
Spanning the plasma membrane
Cell signalling basic description?
Cell receives a signal from outside which causes an effect within the cell
Where are intracellular receptors found?
Within the cell
What must signalling molecules that enter the cell be?
Small and hydrophobic
Why must signalling molecules that enter the cell be hydrophobic?
So they can pass the plasma membrane
Where in the cell can intracellular receptors be found?
In the nucleus or sometimes in the cytosol
What are some outputs of cell signalling?
Survival, growth and division , differentiation
What is the default cell setting?
Apoptosis
What is the result of a cell receiving no signalls?
Apoptosis
What can a signalling molecule do to a cell surface receptor?
Activate it or repress it
What happens after a cell surface receptor is activated by a signalling molecule?
Intracellular signalling molecules are activated/repressed
What do the intracellular signalling molecules do?
They control the effector proteins
What do effector proteins do?
Cause the output
Examples of effector proteins?
Metabolic enzymes, cytoskeletal proteins, transcriptional regulators
How can a signal be amplified within a cell?
One relay protein (connected to the cell surface receptor) can activate many small intracellular messenger molecules.
What is the role of scaffold proteins?
To act as a docking stage for proteins to all come together
What speeds can a response to cell signalling be?
fast or slow
What kind of signalling pathway typically elicits a fast response?
Altering a proteins shape (thus function) as the protein already exists
What kind of signalling pathway typically elicits a slow response?
Altering a transcriptional pathway as proteins take time to be synthesised
Reversal of fast responses?
Fast
Reversal of slow responses?
Slow
What is endocrine signalling?
Involves hormones travelling through the blood to the target cell
What do endocrine cells do?
Make and secrete the hormones involved in endocrine signalling
How is it ensured that the hormones in endocrine signalling only affect specific cells?
Only specific cells have the receptors that are complementary to the hormone, so those that don’t won’t be affected
What is paracrine signalling?
Involves signalling molecules affecting target cells that are close by
What do paracrine cells do?
Synthesise and secrete “local mediators” that binds to receptors on nearby target cells
What is a local mediator?
A paracrine signalling molecule
What is neuronal signalling?
A presynaptic cell secretes neurotransmitter across a synapse to continue an action potential across it
What is a neurotransmitter?
A type of signalling molecule specifically involved in neuronal signalling
What is contact dependant signalling?
The signalling cell holds the molecule on its plasma membrane, meaning the target cell can only be activated if it is in direct contact w/ the signalling cell
When is contact-dependant signalling usually used?
Common when organisms are developing
