Carla - Signal Transduction Flashcards
What four things does cell-cell signalling allow?
Coordination of activities
Keeps cells alive or tells them to die (apoptosis)
Tells cells to replicate
Tells cells to differentiate
What are cell receptors involved in?
Acceptance
Transmission
What are the two main categories of receptors?
Intracellular
Cell surface receptors
Write a note on intracellular receptors
(3)
Found in cytoplasm or nucleus - not near the cell membrane at all don’t touch outside of cell
Ligands are often small and hydrophobic to pass through the membrane
Ligand binds to the receptor and activates it by causing a conformational change
Give an example of an intracellular receptor
Receptors for sex hormones estradiol and testosterone
How do intracellular receptors act as molecular switches?
One of two ways:
- phosphorylation or
- GTP binding proteins
How do intracellular receptors act as molecular switches using phosphorylation?
(3)
By adding phosphates to amino acids of a protein
This can activate a protein
By taking a phosphate off an amino acid a protein can be turned off
How do intracellular receptors act as molecular switches using GTP binding protein?
(3)
Guanosine triphosphate
Guanosine diphosphate is phosphorylated to triphosphate which activates a protein
To turn of the protein the triphosphate loses a phosphate
Write a note on cell surface receptors
(4)
Membrane anchored
Detection followed by transmission
May cause series of biochemical changes or modification of membrane potential = movement of ions i.e. allow more ions to leave etc
Can act directly or can activate intracellular molecules
Classify cell surface receptors
(3)
Ion channel-linked receptors
Enzyme-linked receptors
G-protein-linked receptors
Write a note on ion channel-linked receptors
(2)
Transduction of chemical signals in response to chemical messenger binding
Regulates opening/closing ion channels to allow ions across plasma membrane
What are the four types of ion channel linked receptors
Ligand-gated
Mechanically-gated
Always open
Voltage-gated
Write a note on enzyme-linked receptors
(5)
Single pass transmembrane receptors
Act as enzymes or associate with enzymes
Extracellular binding domain for chemical signalling
Intracellular domain-catalytic action controlled by binding of extracellular ligand
e.g. Receptor Tyrosine kinases
Write a note on Receptor Kyrosine Kinase Receptors
58 known in humans
Involved in mediating cell-to-cell communication
Control a wide range of complex biological functions (growth, motility, differentiation and metabolism)
Explain how Receptor Tyrosine Kinases work
(7)
They act as enzymes or associate with enzymes
They have an extracellular binding domain
Inside they have an intracellular catalytic domain (enzymic domain where tyrosines are found)
A ligand binds which causes dimer formation
ATP molecules donate a phosphate to each of the top tyrosines
The tyrosines proceed to phosphorylate each other
This leads to the switching on of proteins
