cell communications Flashcards
all organisms respond to which 8 stimuli?
light, temperature, sound, touch, magnetic fields, gravity, pH and chemicals
cells in a multicellular organisms send signals and which signals can they be
proteins, peptides amino acids, nucleotides, steroids, fatty acid derivatives or gases
what converts the extracellular signal to the intracellular signalling molecules
receptors
what is signal transduction
conversion of one type of signal to another
cell signalling 3 phases
reception, transduction and response
signals can act over a ______ or ______ range
long or short
what are the 4 types of signals
endocrine
paracrine
synaptic
contact-dependent
what are endocrine signals and how to they act
act over long ranges and are hormones
- remote signals
what do endocrine signals target
distant cells
what do endocrine signals transported by
circulatory system
what ate endocrine signals secreted by
endocrine glands
how does paracrine, synaptic and contact-dependent act
over short range (acct locally)
some examples of locally acting signal molecules and actions?
growth factors (stimulates many cell types), inflammatory factors (causes blood vessels to dilate) and gases (smooth muscle cells to relax)
what does each cell respond to
limited set of extracellular signals
what do cells have that are different?
sets of receptors and signal transduction pathways
what does signal interpretation depend on?
receptor, intracellular effector proteins and other signals received by cell
chemical signals instruct cells to _____?
survive, grow, divide or differentiate
what are examples of fast cell responses (< sec to mins)
change in cell movement, cell shape, metabolism and secretion
what are examples of slow cell responses (mins to hrs)
cell differentiation, division and growth
are cell responses involving gene expression are slow or fast?
slow
what do signal molecules bind to
cell-surface receptors or intracellular receptors
what do extracellular signals molecules that bind to cell-surface receptors look like?
hydrophilic and large
what do extracellular signals molecules that bind to intracellular receptors look like?
small, hydrophobic, extracellular signal cross membrane
where ate intracellular receptors bonded to
cytosol or nucleus
what examples bind to intracellular receptors
steroid hormones such as cortisol
cortisone enters cytoplasm and binds to receptor
receptor changes shape and releases chaperone
receptor and cortisol ligand to enter nucleus
what dissolved gases enter cell and activate intracellular enzymes and how
nitrous oxide
- diffuses across membrane and directly regulate the activity of an enzyme
what does NO trigger
smooth muscle relaxation in blood-vessel wall
what do cell-surface receptors create
new intracellular signals
what can intracellular signalling molecules be
proteins or small messenger molecules
what do effector proteins do
directly affect the behaviour of the target cell
what do intracellular signalling proteins do to the incoming signal
relay, amplify, integrate and distribute
what is signalling relay analogous to
relay race inside cell
what is amplified inside the cell
extracellular signal
what is the incoming signal distributed to
effector proteins
when does a cross talk occur
between different intracellular signalling molecules
what is the activity of proteins and enzymes in a signalling pathways regulated positively or negative by a ???
feedback mechanism
some intracellular signalling proteins act as molecular switches
true (fluctuate between inactive and active)
what happens in an activated state
proteins stimulate/suppress other proteins
some molecular switches are activated by what and how (P)
phosphorylation by protein kinases
inactivated by dephospho rylation by protein phosphatases
2 main types of protein kinases
serine/threonine kinases and tyrosine kinases
some molecular switches are activated by what and how (G)
GTP binding
cell-surface receptors 3 main classes
ion-channel-coupled receptors (ligand-gated ion channels)
G-protein-coupled receptors
enzyme-coupled receptors
what is GPCRs
largest family of receptors (more than 700 types)
what do stimulation of GPCRs activates
G-protein subunits
what are G protein activated by
set of receptors and activates set of target proteins
the g-protein is a
molecules switch (switches itself off)
what does acetylcholine signal do?
acetylcholine signal transacted to k+ channel and slows down heartbeat
2 most frequent target enzymes for G proteins
adenylyl cyclase
phospholipase C
GCPRs activate 2 principal
signal transduction pathways
adenylyl cyclase generates
cAMP
how is cyclic amp generated and degraded?
generated = adenylyl cyclase
degraded = cyclic amp phosphodiesterase
cAMP signalling pathways activates??
gene transcription
what is epinephrine
adrenaline
what is related to door perception
GPCRs and cAMP signaling
what does the phosphatidylinositol signalling pathways trigger
rise in intracellular ca2+
what leads to saliva secretion
phosphatidylinositol
signaling pathway
calcium binding changes shape of
calmodulin protein
what relates to taste perception
GPCRs and phosphatidylinositol signaling
five taste classes
sweet, salty, sour, bitter and umami
what taste is detected by GPCRs
sweet, umami and bitter
what is GCPRs responsible for
light detection in rod cells in retina
signals binding RTKs are
growth factors and hormones
2 signalling pathways activated by RTKs
ras/mark signaling
pi3k/akt signaling
RAS is a
G protein and molecular switch
Was activated a
map-kinase signalling module
activated AKT promotes
cell survival
how do AKT stimulates cells to grow
size by activating the serine kinase TOR
signal transduction pathways are
interconnected
