Cell Death Flashcards
(49 cards)
What are the two main forms of cell deah
Apoptosis
Necrosis
What is apoptosis?
Programmed cell death
What is necrosis?
Cell death by injury
When does apoptosis occur?
Development
Immune response - destruction of excess cells
Cancer therapy - eliminate tumour cells
What happens if there is too much apoptosis?
Neurodegenerative disease
What are the features of an apoptotic cell?
- Cell compaction
- Blebbing and scrambling of membranes
- Chromatin condensation
- DNA fragmentation
- Cell fragmentation into membrane bound pieces
- Engulfment by macrophages
Does apoptosis trigger an inflammatory response?
No
Does necrosis trigger an inflammatory response?
Yes
What causes the inflammatory response in necrosis?
Neutrophils, macrophages and other innate cells
What is the inflammatory system alerted by in necrosis?
Danger signals released by dying cells (DAMPs)
What are the morphological features of necrosis?
- Increasing translucent cytoplasm
- Swelling of organelles
- Condensation of chromatin into small patches
- Increased cell volume leading to disruption of plasma membrane
Why does a cell undergo apoptosis
- if a cell has sustained a large amount of damage which cannot be repaired or would take a large amount of energy to do so
- the cell has outlived it’s usefulness
- the cell has become senescent
- the death of the cell is needed for the organism to reach it’s final embryonic development
- the death of a cell is necessary for maintaining part of a physiological process of an organism
Syndactylyl
The cells in the interdigital space which have failed to undergo apoptosis and therefore the outcome is that the foetus is born with webbed hands and feet
Which cell can be used for apoptosis?
cytotoxic T cells
how are initiator caspases activated?
Protein:protein interactions
How are effector caspases activated?
proteolytic cleavage
During apoptosis activation, where does proteolytic cleavage occur?
Death-effector domain
Where are death effector domains present?
Procaspases
Proteins which regulate caspase activity
Give an example of a protein which regulates caspase activity
FAS-associating death domain-containing protein (FADD)
Function of FADD
recruits procaspase 8 and 10 to the death induced signalling complex (DISC)
How does procaspase recruitment occur
The interaction between DED of the procaspase and the adaptor molecules associated with TNF receptor
Function of caspase 3
Cuts DNA
Function of caspase 6
mediates nuclear shrinkage during inflammation
Function of caspase 8
linked to two cells which are together, if one is not functional then the signal is sent to caspase 8
