L1 Flashcards
Lecture one
intercellular communication =
cell signalling which is a multistep process
step 1 of cell signalling
synthesis of signal molecule
step 2 of cell signalling
release of signal molecule
step 3 of cell signalling
transport of signal molecule to target - signal will be degraded on the way
step 4 of cell signalling
detection of signal (reception) by target cell by a receptor
step 5 of cell signalling
response by target cell - the action the signal said it’d do
step 6 of cell signalling
some form of feedback - signal has been received
Possible chemical nature of signal
- steroid (e.g. testosterone)
- amino acid
- amine
- gas
- peptide
- protein
water soluble or lipid soluble?
can be stored in lipid vesicles within the signalling cell
water soluble
water soluble or lipid soluble?
rapid release via exocytosis
water soluble
water soluble or lipid soluble? why?
travels in blood without a carrier
water soluble
because blood is watery so don’t need to bind to a carrier molecule to travel in blood
water soluble or lipid soluble? why?
cannot enter target cell
water soluble
can’t cross cell membrane because of the phospholipid bilayer
water soluble or lipid soluble? why?
message transduced via cell surface receptor
water soluble
because ligand cannot enter cell itself
water soluble or lipid soluble?
cannot be stored in lipid vesicles within the signalling cell
lipid soluble
water soluble or lipid soluble? why?
slow response
lipid soluble
because it must be made on demand
water soluble or lipid soluble? why?
travels in blood with a carrier protein
lipid soluble
because blood is watery - may be longer lasting
water soluble or lipid soluble? why?
can enter cells by crossing membrane
lipid soluble
can cross phospholipid bilayer
water soluble or lipid soluble? why?
acts on intracellular receptors
lipid soluble
directly regulates gene expression as it can enter the cell
juxtacrine 1.0
specificity achieved by
direct contact i.e. doesn’t have to leave a cell, travel and enter another cell
juxtacrine 2.0
specificity achieved by
receptor expression and direct contact
autocrine
specificity achieved by
selective receptor expression and rapid degradation of signal molecule
paracrine
specificity achieved by
selective receptor expression and rapid degradation of signal molecule, only cells that have the right receptor will receive the signal
endocrine
specificity achieved by
selective receptor expression, only cells with the right receptor will receive the signal
neuronal
specificity achieved by
precise contacts and rapid removal of neurotransmitter to prevent diffusion, ignores other neurons beelines for the right ones
neuroendocrine
specificity achieved by
important in regulation of the endocrine system
why is this ligand sent?
grow
if cell divided and cells are half the size of the original need to grow
why is this ligand sent?
divide
to make more of a cell
why is this ligand sent?
die
if cells are cancerous or diseased, cells will send messages to die
why is this ligand sent?
change
change form or differentiate
why is this ligand sent?
become active
contract, move, fire an AP, release a signal of its own, make more of something e.g. a hormone, break down more of something
How do the signals’ effects occur
- receptor activation by a signal may change the amount or the activity of specific proteins which then mediate an effect
- proteins provide the structure of the cell (structure reflects function)
- enzymes do the activity
if you want a cell to do something you want to target what the proteins do as cells can’t do the right thing without the right structure/can do what you want if you give it the right structure
what alters can be made to change the activity of a gene? (2)
- alter gene expression of specific proteins (turning specific genes on or off)
- alter the activity of specific proteins
cell signalling often does both
