Apoptosis Flashcards
What is apoptosis? where is it observed?
- cell dying
- removal of cells
- active form of regulation by death of cell.
- deaths mediated by the apoptoyic machinery
it is observed in multicellular animals , maybe protozoans
what is active cell suicide ?
a mechanism used by Multi-cellular animals to remove cell that are in excess, in the way or potentially dangerous
- cells are engulfed when dead
why is there a need to get rid of cells?
body building :
- neural tube formation
- separation of digits( separation of webbed fingers)
- loss of superfluous structures (e.g. tail from tadpole for frog)
Maintaining the machine:
- keeping cell number constant/ safety in numbers - nervous system development
- homeostatic control of cell numbers
better dead than wrong (elimination of potentially dangerous cells ):
- T and B cell development
- viral infections
- cancer surveillance( apoptosis can prevent cancer!)
programmed cell death is required for the normal pathology of diseases?
inappropriate inactivation of the death program in:
- cancer
- autoimmune diseases
inappropriate activation of the death program in :-
- chronic neurodegenerative diseases
- stroke
- myocardial heart infarction
- AIDS
- hepatic diseases
What is programmed cell death ? where is it observed in?
- type of death in which a cell , in response to specific signals undergoes a regulated and reproducible series of events that will lead to its death !
- it is observed in : animals , plants , fungi, prokaryotes
What is the difference Apoptosis and Necrosis?
Apoptosis - programmed cell death
- cell shrinkage
- most organelles not affected until late in the process
- chromatin condensation
- plasma membrane integrity maintained
- break up of cell into apoptotic bodies
- no inflammation
Necrosis - unprogrammed cell death
- cell swelling
- early organellar dysfunction
- limited chromatin marginalization
- loss of plasma membrane integrity
- cell lysis
- inflammation
What are types of cell death ?
Programmed cell death
- apoptosis
- Autophagy
Unprogrammed Cell death
- necrosis
What is Necrosis ?
- cell injury resulting in premature death of the cell.
what the morphological features of apoptosis?
- chromatin condensation and marginalisation
- cell shrinkage associated with membrane blebbing
- most organelles not affected until late in the process
- break up of cell into membrane bound - ‘apoptotic bodies’
Purposes of clearing apoptotic cells?
- recycle cellular contents
- prevent release of potential toxic intracellular contents into the medium
- modulate the immune system
- insure that the death program gets completed
Biochemical features of apoptosis?
- cleavage of genomic DNA into oligonucleosomal fragments (DNA ladder)
- exposure of phosphatidylserine on the cell surface
- Release of Proteins from the intermembrane space of mitochondria
- proteolytic processing / cleavage of over 100 proteins.
What is a scramblase?
- Scramblases- is a protein responsible for the translocation of phospholipid
What are flippases?
Scramblases are members of the general family of transmembrane lipid transporters known as flippases.
What effect does PS (phosphatidylserine) have on apoptosis?
phosphatidylserine (PS) exposure during apoptosis requires inhibition of Flippase(s) and activation of Scramblase(s)
How does protein cleavage during apoptosis work?
- protein cleavage during apoptosis is specific and selective ( cleavage is causes by caspases- cysteine proteases that play essential roles in apoptosis, necrosis, and inflammation. )
