deck_614136 Flashcards
What can signalling occur between?What are three types of chemical signal classification?
Between secreted molecules and between plasma membrane bound molecules Endocrine - HormoneSynaptic - NeutransmissionParacrine - Chemical Mediators
What is hormonal signalling?
Signalling between cells in different tissues via the circulation
What kind of signalling do neurotransmitters do?
Signalling at specialised cell junctions in the nervous system at synapses
Define paracrine signalling
Signalling where the target tissue is close to the cell releasing the hormone xc- local chemical mediators
Define ligand
Any small molecule that binds specifically to a receptor site
What kind of action does an agonist ligand bring about?
Agonist activate receptors
What action does an antagonist ligand bring about?
In binds with a receptor without causing activation– opposes the agonist
What is the name for an agonist that stimulates a receptor but does not elicit a maximum cell response?
Partial agonist
Define receptorWhat occurs when the receptor is in an unbound state
A molecule that recognises specifically a ligand or family of ligands. In response to ligand binding. It brings about regulation of a cellular process Unbound state = functionally silent
What does the binding of adrenaline to a B-adrenergic receptor activate?
It activates adenylyl cyclase which activates a cascade of events inside the cell.
Which has a higher affinity: ligand binding at a receptor or substrates and allosteric regulators to enzyme sites?
Ligand binding at receptor sites
Give some examples of the roles that receptors have? (8)
• Signalling by hormones/local chemical mediators• Neurotransmission• Cellular delivery• Control of gene expression• Cell adhesion• Modulation of the immune response• Sorting of intracellular proteins• Release of intracellular calcium stores
How are receptors classified?
By which signal molecule they recognise before being subclassed in to their affinity for certain antagonistse.g. ACh receptors can be nicotinic or muscarinic but both will bind to nicotine and muscarine.
What are the differences between receptors and acceptors?
Receptors – are silent at rest and agonist binding stimulates a biological responseAcceptors – can operate in absence of ligand.
How has evolution solved the problem of transducing extracellular into intracellular signals?
The receptor and the effector molecules are on separate proteins but are coupled by a transducing protein.
What are the four methods of signal transduction?What are the relative speeds of change for each process?
- Membrane-bound receptors with integral ion channels2. Membrane-bound receptors with integral enzyme activity3. Membrane-bound receptors which couple to effectors through transducing proteins4. Intracellular receptorsFast to slow – 1 to 4