Biological signalling molecules Flashcards
What are the types of extracellular signalling?
Endocrine
Paracrine
Autocrine
What is paracrine signalling?
Cell releases signalling molcule
diffuses to nearby cells
binds to receptors on those cells
cause effects in those cells
What are some examples of paracrine signalling molcules?
Neurotransmitters
Local chemical mediators
What are the types of neurotransmitters based on their structure?
Amino acids
Monoamines
Peptides
Acetylcholine
What are the types of neurotransmitters based on their effects on the post-synaptic neurone? What do they each mean?
Excitatory - increase action potentials in post-synaptic neurone
Inhibitory - decrease action potentials in post-synpatic neurone
What are some examples of amino acid neurotransmitters?
Glutamate
Glycine
What are some examples of monoamines neurotransmitters?
Adrenaline
Noradrenaline
Dopamine
What are some examples of excitatory neurotransmitters?
Adrenaline
Noradrenaline
What is an example of a neurotransmitter that is both excitatory and inhibitory?
Dopamine
What are the types of local chemical mediators?
Cytokines
Eicosanoids
What are some examples of cytokines?
Chemokines
Interleukins
What are some examples of eicosanoids?
Prostaglandins
Leukotrienese
What is autocrine signalling?
Cell releases signalling molecules
bind to receptors on same cell
cause effects in same cell
How does paracrine signalling relate to autocrine signalling?
Some paracrine signalling molcules are also autocrine signalling molecules e.g. cytokines
How are signalling mechanisms categorised into endocrine, paracrine and autocrine?
Based on the distance over which the signalling molcules act
How are signalling molecules used clinically?
Can synthesise exogenous molecules that resemble the endogenous ones
Give exogenous molecules that attempt to mimic the endogenous ones
What are the types of signalling molecule targets?
Receptors
Ion channels
Transporters
Enzymes
What are the exceptions to types of signalling molecule targets? Why?
Chemotherapy, antibiotics
target DNA, structural proteins
What are the types of receptors?
Kinase-linked receptors
Ion channels - ligand-gated
Nuclear/intracellular
G-protein coupled receptors
What do kinase-linked receptors do?
Phosphorylate proteins
What does kinase-linked receptors phosphorylating proteins lead to?
Gene transcription
protein synthesis
What do ligand-gated ion channels do?
Ligand binds to them causing them to open
allow specific ions to pass through them down their electrochemical gradient
What does ions passing through open ligand-gated ion channels lead to?
Change in membrane potential
gives depolarisation or hyperpolarisation
What do nuclear/intracellular receptors do?
Ligand-recetor complex migrates to nucleus if not already there
bind to transcription factor
activate/inactivate genes
What are the types of ion channels?
Voltage-gated
Ligand-gated
How do voltage-gated ion channels work?
Change in membrane potential causes them to open
The change in membrane potential is brought about by ligand-gated ion channels opening
How can ion channel activity be modulated?
By phosphorylation of intracellular sites by protein kinases
By allosteric regulation by e.g. ATP
How do ligands of nuclear/intracellular receptors react to lipids? Why is this important?
They are lipid-soluble
important because it allows them to diffuse across the plasma membrane and into the cytoplasm
