Cell Death Flashcards
Ways cells can die
Apoptosis or necrosis
What is necrosis?
When cell’s defences are overcome. Due to unexpected/accidental cell damage
Which process of cell death is uncontrolled?
Necrosis
Problems with necrosis
Debris may damage surrounding cells
What can cause necrosis to occur?
Physical damage Restriction in blood supply Infections Acute toxicity Rapid loss in cell energy
What is apoptosis?
Controlled cell death
When does apoptosis occur?
Developmental cell loss
Senescence
Chronic toxicity
Removal of growth factors
Can both processes of cell death ever be involved in the death of a cell?
Yes, in a brain ischaemia.
Cells in middle die through necrosis
Cells on outside die through apoptosis
Examples of when apoptosis is occurring
Formation of digits in humans
Tadpole –> frog, tail cells die
In the C. elegans (nematode worm), how many cells die during development?
131 cells die
How many genes are involved in apoptosis? What kind of genes are they?
10
CED genes
What are the 4 key genes in apoptosis?
1) EGL-1
2) CED9
3) CED4
4) CED3
What is the pathway of the CED genes?
EGL-1 –| CED9 –| CED4 –> CED3 –> cell death
What does EGL-1 do?
Initiate apoptosis by inhibiting CED9
What does does a decrease in CED9 cause?
Massive cell death
What does a decrease in CED3 and CED4 cause?
Excess adult cells
What does CED9 do?
Prevent cell death
What does CED3 do?
Cause cell death
What does CED4 do?
Cause cell death
Which CED gene/s cause cell death?
CED3 and CED4
Which CED gene/s prevent cell death?
CED9
What are caspases?
Executioners of/Carry out cell death
What would happen if there was no caspase acitivity?
No apoptosis
What process activates caspases?
Proteolysis
Which caspase is important in development?
Caspase 3
Three ways in which caspase 3 is important in development
Breaks down:
- lamin A
- huntingtin
- DNA repair enzymes e.g. PARP
What is the intrinsic pathway for apoptosis?
Cytochrome c is released from mitochondira
Binds to APAF-1 and caspase 9 which triggers a cascade
What does cytochrome c bind to?
APAF-1 and caspase 9
What does caspase 3 break down?
Breaks down:
- lamin A
- huntingtin
- DNA repair enzymes e.g. PARP
