Cell Signalling Flashcards
Intercellular
Between cells
Types of signals
Chemical- majority (short eg neurotransmitter and long range eg hormones)
Physical
Gaseous
Chemical intercellular signalling steps
Synthesis and release of the signalling molecule
Transport of signalling molecule to target cell
Detect signal by specific receptor
Change in cellular behaviour triggered by activation of the receptor
Removal of the signal
Chemical messenger signal molecules Examples
Insulin, hormones, sugar, peptides, proteins, neurotransmitters
What is an agonist
Where are signalling molecule binds and activate a receptor
What is an antagonist
A signalling molecule that binds and inactivates receptors
Receptors are specific and mostly
Proteins on the cell surface or cytoplasmic
Different cells express different
Receptors
What causes a quick reaction
Usually ion channels
What causes a relatively quick action
G-protein coupled receptors
What causes a slow reaction
Kinase linked receptors and nuclear receptors
One signalling molecule can activate different
Receptor types
Endocrine signalling
Hormones are long-range, they are usually slow chemical communication e.g. insulin, cortisol
Paracrine signalling
Short range e.g. nitric oxide
Neuronal signalling
Uses neurotransmitters
Autocrine signalling
Signalling molecule binds to itselfs receptors
Juxtacrine signalling
Contact dependent signalling and uses gap junctions
Intracellular signalling
The receptor activation leads to intracellular signalling cascades and second messenger
Three stages of intracellular signalling
Reception- CM binds to a protein on CSM
Transduction – binding alters receptors which causes a cascade of reactions
Response – transduction triggers a response e.g. release of enzyme
Examples of second messengers
cAMP, InSP3, DAG
Signalling molecules are controlled by
Post-translational modification, regulate if a G protein is activated, activators of proteins- The binding changes the confirmation of target proteins which changes the activity
Types of receptors
Ligand gated ion channels (iontrophic) , G protein receptors, kinase linked, nuclear receptors
Ion channels transport
Sodium, potassium, calcium and chlorine very quickly.
They open due to voltage gated ion channels
Ionotrophic receptors open in response to
The binding of a ligand
G protein coupled receptors have alpha and
Beta and gamma receptors
Alpha receptors activate
An enzyme which causes a cascade of reactions
Gamma receptors have an
Alpha receptor attached which is an activated so GDP turns into GTP
What do you proteins are activated by agonist
GI, GS, GQ
GS
Agonist binds and activate adenyl cyclase which causes an increase in CAMP
Gq
Activate phospholipase C which activates IP3 which activates calcium and PKC and then DAG
Gi
G I blocks adenyl cyclase so cAMP is not synthesised and there is less cAMP
Inhibitory pathway
Enzyme linked receptors Are slower and their stages are
Signalling molecule binds, activates an enzyme e.g. protein tyrosine kinase activity, phosphorylates
CytoplasmMatic/nuclear signalling
Alters gene transcription directly
