Apoptosis Flashcards
What are the 2 ways cells die?
Necrosis & Apoptosis
What is necrosis?
associated with external damage
What is apoptosis?
programmed cell-death
How many cells die a day?
50 billion cells per day
When does necrosis?
Physical damage
- trauma e.g. cuts & burns
- extreme temperatures e.g. frostbite
Toxins
- external e.g. snake venom
- internal e.g. bacterial toxins
- acute hypoxia/ischemia e.g. stroke
When does apoptosis occur (physiological situations)?
Physiological situation:
- tissue size maintenance
- developmental cell loss - growth
- removal of immune cells
- hormone - dependent involution
- inappropriate interactions - anoikis
When does does apoptosis occur (pathological situations)?
- DNA damage e.g. radiation, exidative stress
- Virally infected cells
What are reversible characteristics of necrosis?
- membrane integrity compromised
- organelle and cell swelling
What are irreversible characteristics of necrosis?
- increased intracellular calcium
- autolysis
- cell bursting (cell lysis)
- elicits an inflammatory response
What type of cell death is brain ischaemia?
- both necrosis & apoptosis involved
- cells in middle die via necrosis
- cells at edge die through apoptosis
- this restricts spread of cell death
What is an example of developmental apoptosis?
Digit formation in mice - apoptosis is initiated through the release of local signal proteins
What genes are a good model for studying apoptotic pathways?
Ced genes
What do Ced genes?
involved in the apoptotic signal to engulfment of apoptotic cell by phagocytes
What are caspases?
The executioner of cell death - essential for apoptosis
What amino acid is at the active site of a caspase?
cysteine
