W6 Cell Signalling Flashcards
how do cells know when to move or proliferate
signals
What happens when the signal reaches a cell
intracellular biochemical reactions
what is spatial regulation
which specific cells/organ
what is temporal regulation
when processes should happen in a cell
how do cell signals get into the cell
gap junctions
how do adjacent cells communicate
direct cytoplasmic communication
what are connexons
what are connexons made of
6 connexins
what are lots of cell to cell channels
gap junction plagues
what are connexins made of
4 transmembrane domains (M)
2 extracellular loops (E)
1 intracellular loop (CL)
N + C terminus
how do hydrophobic ligand enter
via plasma membrane
why do hydrophilic ligands bind to receptors out of cell
cant enter the plasma membrane
what happens when the hydrophilic ligan binding do
extracellular signal to intracellular signal
how does the cell cycle restart
no signals to convert DNA to RNA
no release of p27Kin1
why does no p27Kin1 restart cell cycle
cyclin E not inhibited
where are intracellular signalling molecules released from
intracellular stores
what type of model do intracellular signalling molecules use
2nd messenger model
are ligand gated channels active or passive
passive
what are GPCRs
g protein coupled receptors
what do G proteins do
activate membrane bound effectors
when activated what do G proteins bind to
GTP
when inactive what do G proteins bind to
GDP
How do GPCRs turn off
intrinsic GTPase rebinds to beta gamma subunit
what are GPCRs
largest cell signalling receptor
what happens in the adenyl cyclase pathway
- cAMp is converted to PKA
- signals target proteins for glucose metabolism
how do you stop the adenyl cyclase pathway
add cAMP phosphodiesterase
what happens after a molecule is phosphorylated
- increased hydrophilicity
- activates proteins
how do you increase kinase activity
autophosphorylation of tyrosine kinase
describe the process of MAPKs cascade
- activation of cell surface receptors
- activates Ras protein
- Ras protein activates MEK pathway
How can we stop a transmembrane signalling cascade
- inhibit receptors
- stop intracellular signalling proteins
describe the process of the PI3K/Akt cascade
- GPCRs is activated by ligands
- activates PI3K
- this recruits Akt
- activated Akt promotes cell growth
how to turn off tyrosine kinases receptors
Phosphatases
what happens when there’s no signalling cascade pathways
mRNA doesn’t leave nucleus for transcription so less cell growth
what does degrading 2nd messenger do
stop transmembrane signalling cascade
