Please enable JavaScript.
Coggle requires JavaScript to display documents.
1-Biochemical Messengers : cell signalling (16 oct) (1-cells communicate…
1-Biochemical Messengers : cell signalling (16 oct)
1-cells communicate to
try convince other cells to
modify their behaiviour
convincing starts with message
type of msg is highly varied
from complex proteins
bits of modified amino acids
gasses: nitrid oxide to change blood flow
gene transcri.
secretion
secrete enzymes
secrete ions
other molecules that change how other cells behave
enzyme activity
when cells change their behaviour
it changes its function
change in phenotype: from stem cell to neuron by being exposed to biochemical messengers
change in fate
change in function
we modify which gene switched on
we modify the activity of certain enzymes
"""how that cells talk to other cells
by changing what secreted from the cell
2- how do cells change?
if we want to change how genes are expressed
the quickest way: to change what transcription factors
there are present
change in transcription takes about 12 hours
generic transcription factors
highly specific trans. fac.
transcript. fac. enter the nucleus and change what genes are expressed in the cell
change the activity of enzymes
a large number of enzymes that are produced in the cell
produced as inactive precursor
protein is present but not yet being activated
thing to do to activate them
phosphorylation:
sticking a phosphate group on them
imp. on activating enz that are present in the cell
super quick: 12 mili seconds
it changes the polarity of the molec.
chane in the shape of the molec.
enzyme to put on phosphate : kinase : typically activates
enzyme to take off phosphate: phosphatase: typically represses
we can sequester these enzymes:
have them as a part of big complex
complex might envolve things
co activators
co-corepressors
if enzyme is bound by co repressors
1 more item...
some pathways work by changing the activator or repressors that are parts of the enzyme complexes
secretion
different parts of the body to secret things
gastrointestinal tract
pancreas
how nerves actually talk to each other
by neurotransmiters
1 more item...
3- cell communicatios
highly varied and various
the types of audience is important
if we need broad audience, eg . to increase the metabolism in our body>>> done by thyroid hormon receptor
instead of using a precise delivery of these biochemical messengers we just dump them into our blood
sometimes we need to influence
a very small number of cells
very small audience
deliver biochemical messengers in very precise way that is what nerves do
distance is also important:
some nerves can function over a huge distance: nerves from spinal cord go all the way to our foot more than a meter
pump hormones into our blood and
we make sure that blood gets into our feet
immediacy
fight or flight response
pump adrenaline in the body
do not want that fight or flight respond to last
usually lasts for 25 minutes
duration
hormones that regulate basal metabolism
thyroid hormones last longer
to have stable metabolism
some processes need to be regulated over very long period of time
need to be used in lots of different applications
4- one cell is producing
extracellular signalling molec.
dump it in :
to blood
short space of extracellular fluid
between a few cells
diffuses and bind to a receptor
without receptors our cells can not respont to
biochemical messengers
any cell that has a receptor for this signalling molecule can undergo change : we get signal transduction :star:
signal transduction:
converting the extra cellular signal to intra cellular signal
transducing the extra cellular signal in some sort of change inside the cell
chages:
alter protein function
phosphorylation or association with sth
change gene transcription
2 mechanisms have different rates of activity
altering protein function
fast: we get very rapid response and then will be switched off straight away
altering transcription: takes minutes to occur
the effect can last for days
signal transduction
produce a signal molecule that
get released and transported
binds to a receptor
signal transduced in some
chage in cell behaviour
5- communication components
synthesis of signaling molec.
if our cell are responsive to signals
or able to make signals
they need to have all the equipment that
they need to produce signals or to respond to signals
so the first part is setting up
the communication scheme
producing the signaling molecule
sometimes
we produce the signalling molecules
by transcription and translation
but there are other mechanisms that
we can produce them as well
producing the receptors:
make sure they are available
all receptors are proteins
all rec. are produced by transcription and translation
when we want to signal
we need some stimulus to release
can be very varied
if we have a protein based signalling molecule
gets exocytosed out of the cell
signals need to
get transported
type of transport
depends on 2 things:
distance
for long way: use blood
biochemistary of the signalling molecule
hydrophilic signaling molecule
dump it into blood
hydrophobic signalling molec.
does NOT dissolve in blood>>> depends
binding to receptor
receptor activates signal transduction
or intracellular signalling inside of
the cell in response to that mechanism
that then changes function
we use these messengers inside the cell
messenger outside the cell: first messenger
messenger inside the cell : second messenger :star:
1 more item...
6- extracellular signalling
in distance we have 5 different
types of signalling
1) endocrine signalling : HORMONS :star:
endo:inside
crine: type of signalling we are using
being secreted directly into the blood
passing along the blood stream
and binding to target cells
another type of crine
a cell can signal to itself
a lot of immune responses in our cells,
like the activation of cells is
an 2) AUTOCRINE response :star:
cell produces signalling molec.
it secretes and binds to exactly the same cell
signall to a cell that is next to us
3) paracrine :star: signal released by the call
release the signal ino local area>>>
it diffuses and binds to nearby receptors
4) juxtacrine :star: signal stays attached to the cell membrane
only signal to the exactly the cell that next to us
the receptors are bound on one cell and
the signalling molecules are bound to another cell
usefull for how nerves grow in the developing brain
they find their way by touching other cells by juxtacrine signalling
5) synaptic signalling :star:
how all or most of the cells in the body work
we have very long cellular projection(sth that sticks out)
and we project to the cells that we want to influence
we have our receptors on our target cells
biochemical messengers stored in our neurons
we can achieve large distances because our cells can project their cytoplasm large distances away
7- benefits and limitations
long distance signalling
faraway communication
slow
accumulating in our blood and
getting into the part of body where it is needed
it is going to be a time delay
more generalised
communicating with lots of cell types
need much greater amounts of the signalling moleculed
get diluted in blood
short distance signalling
main benefit: super fast and super presize
time for diffusion of the sig. molec. is very small an it is super precise : you can make contact to the cell that you want to talk to
dont have concentration issues with this
we can dump 100
neurotransmitters into a sinaps
they all going to bind to receptors
becaus. they are not being diluted in blood (which is a real problem in long distance signalling)