chapter 9 Flashcards
paracrine signalling is characterized by ligands that are
secreted by neighboring cells
endocrine signalling- define
horomones enter circulation and carried to target cells distance away
direct contact refers to :
molecules on plasma membrane of one cell contact receptor molecules on an adjacent cell
define synaptic signalling
neurotransmitters released by neurons into synapse
signal transduction pathways :
a) are nessecary for signals to cross the membrane
b) include intracellular events stimulated by EC signal
c) ec events stim’d by IC signal
d) only found where signal can cross membrane
b) include IC events stimd by EC signal
the function of a ________ is to add phosphates to proteins and the function of a ________ is to remove phosphates from proteins
protein kinase, protein phosphotase
which of the following is NOT a membrane receptor channel linked enzymatic gpcr steroid
steroid horomone receptors are intracellular bc nonpolar hydrophobic steroid horomones cross membrane
how does ic receptor differ from membrane receptor
intracellular receptor binds to DNA
signaling through receptor protein kinases often?
leads to activation of a cascade of kinase enzymes
what is the function of Ras during tyrosine kinase cell signalling
links receptor protein to MAP kinase pathway
what is the immediate effect of a ligand binding to a GPCR
G protein trimer releases gdp and binds to gtp
the action of steroid horomones is often longer lived because
they turn on gene expression to produce proteins that persist in the cell
calcium ions can act as second messengers because
it is normally at a low level in the cytoplasm,
different receptors can have the same effect on a cell because
signal transduction pathways intersect- same pathway can be stimulated by different receptors
in comparing small g proteins such as ras and GPCR proteins we can say that:
both proteins have intrinsic gtp ase activity that stops signalling
both proteins are bound to an active GTP
the same signal can have different effects in different cells because
there are different receptor subtypes that initiate different signal trans pathways
may be different co activators
may be different target proteins in different cells signal pathways
all are true
receptors of steroid horomones and peptide horomones are different because
peptides are hydrophillic and steroids are hydrophobic
ligands_____________
a wide variety of moldecules that bind to internal(hydrophobic) or external(hydrophillic) cell receptors
true or false a signalling network is always linear
false
steroid horomone estrogen binds to which cell surface receptor?
none- hydrophobic steroid horomones bind internally
cell commmunication begins with a ____ that binds to a ____ initiating a ____ that leads to a ____
ligand, receptor. signal transduction pathway, cell response
Calcium as a second messenger can
bind to calmodulin to activate cell response proteins
phosphorlyation cascades can be organized by
scaffold proteins which sequester enzymes from other signalling pathways
upon GPCR activation phospholipase C can cleave inositol phospholipids to create
IP3 and DAG which have different signalling consequences
when enough calcium is released into cyto plasm , in can saturate calcium binding sites of calmodulin which causes calmod to change shape and allows it to bind to new proteins (T/F)
truuuuuuuuu
epinepherine and glucagon are different ligands which can initiate the same series of events in a single celll, and epinepherine can initiate different responses in different cell types t/f
true
if a ligand binds with a __ it will __ and if the ____ is gtp bound it could initiate a ____
receptor tyrosine kinase, dimerize and autophosphorylate, activator, phosphorlyation cascade
