cell fate and responding to signals Flashcards
what leads to cell death
no signals or not appropiate one
what does the death signal lead to
activation of suicide proteins and the cell dies
what does no death signal lead to?
sicicide proteins being inactive and the cell lives, it engulfs the other cells which have been told to die
why does cell death need to be controlled?
contain the contents
lysosomes for example would be bad if spilled out
what mediates death signals?
specific extracellular ligands that bind to specific cell surface receptors initiating intracellular signals
what does CED9 do without death signals
stays active which iactivated other CED proteins
what does CD9 do with death signals
becomes inactive
allows other CED proteins to become active and bring about changes in the cell for death
what is cell growth
getting bigger and increaasing size involved synthesis of new proteins and membrane lipids metabolism replication of DNA increase organelles
what is growth controlled by?
growth factors
contact with adjacent cells
nutrient availability
key features of cell proliferation
replication of DNA and divison o make two daughter cells
follows a growth phase
difference between cell growth and proliferation
cell growth doesnt increase cell number
proliferation does
describe the positive growth stimulating pathway
growth factor binds to tyrosine-kinase receptor causes G-protein to phosphylate protein cascade stimulated goes to nucleus tranciptional factor is produced affects gene expression proteins made to stimulate cell cycle
deescribe the negative growth inhibition pathway
growth inhibition factor binds to a receptor
causes G-protein to be phosphylated
protein-kinase cascade
transciption factor made
can be defective or missing a proteins meanin trasciption cant be activated
cell cycle inhibited and division stopped
where do growth signals come in the cycle cycle
G1
what is the cell cycle checkpoint?
traacks the pathway and biochemical chechpoints along the way to ensure cells are okay
how does the cell cycle progres?
at each stage checkpoints are removed
if they arent, cell knows somethin wrong so cant continue
where does the G1 chekcpoint come from?
outside the cell
what is cell differentiation
process by whch cells become specialsed types of cells
usually involves tem ceasing to proliferate
process of muscle differetiation?
stem cells differentiate into a myoblast
expression of other muscle speicific genes causes more differentiation and proteins to be made
fusion of budles of myoblasts
the cell cycle inhibited and a muscle made
one a gene level, how is a muscle made?
signal comes to the gene, stimulates transciption
MyoD protein factor can bind activating lots of things
master control factors then regulate other factors and proteins
what type of extercellular inputs can there be?
ECM cell-cell hormones growth factors cytokines
what type of intacellular signals can there be?
protein kinase
cAMP
ion changes
G-proteins
what type of cel fates can there be from signals?
growth
survivial
death/ apoptosis
differntiation
