mitochrondria: cell death Flashcards
what is apoptosis>
programmed cell death
what is necrosis?
uncontrolled cell death
cells swell up and burst contents
what is necrosis assocated with?
disease
what causes necrosis
cells encounter toxin and then burst releasing this to neighbouring cells
what happens during necrosis?
lose membrane integrity/ control of membrane cell swells cytoplasm dilutes, slow reactions cells lyse loss of cell components inflammation endosomes and lysosomes released DNA degraded
what happens during apoptosis
membrane blebbs but remains in control
cells still viable
careful breakdown of nucleus and components
cell is packaged into small vesicles and contained
what happens to apoptosis fragements?
macrophages can digest the small fragments
how is cell death key in embryo development
it sculpts the tissue
eg. digit making
how is cell death used in the immune system ?
destroys self reacting cells
stops autoimmune issues
destroys virus infected cells
how is cell death used in homeostasis?
counter balance cell division and removal of old or damaged cells
replace with new instead of repearing
how is cell death used in cancer?
radiothereapy drugs work through inducing apoptosis
many cancer cells have defects in apoptosis pathway making them reistant
what are the two ways apoptosis is triggered?
receptor mediated
mitochondrai mediated
how does the receptor mediated pathway work>
recieve correct ligand and this triggers the death pathway
it is extrincically controlled
how does the mitochondrai control cell death?
intrisinic pathway
can be activated by variety of cell stresse
which cell stresses can lead to mitochondrial acttivated cell death?
free radicals DNA damage viral infection membrane damage loss of survival signals
what are caspases?
family of proteases existing in an inactive form of pro-enzymes in cells
how many caspases are there??
12
what do caspases do?
activate other caspases in a cascade.
how do caspases work in activating other caspases?
they cleave the pro-domain and activae the caspase to work
two types of caspases?
initiator
effector
what does an initiator caspase do?
activated other caspases
single caspase can activate lots of others in the cell
what does an affector caspase do?
called executeres
they break down cellular components such as the cytoskeleton and DNA
activation of these is the point of no return in process of apoptosis
how is the plasma membrane involved in cell death
key lipids are made on the inside and the membrane can flip over to reveal this
what causes the membrane to flip over?
caspases
