Apoptosis and Necrosis Flashcards
Necrosis is ____ death. Rapid cell swelling and lysis are characteristic features. It is usually due to damage to the _______. It usually occurs when cells are exposed to an unfavorable physical or chemical environment that causes trauma to the cell.
Apoptosis is ______ cell death or ‘‘death with dignity’’ that is mediated by an internally coded suicide program. It maintains membrane integrity and does not spills its contents.
Accidental death
Cell membrane
Programmed
An influx of water and extracellular ions leads to swelling of the organelles, especially mitochondria, rough ER and nucleus. Eventually, this swelling lysis the plasma membrane and all of its content is released. This process is very pro inflammatory. That process refers to :
Necrosis
Nuclear changes in necrosis can occur in 3 steps which can be identified on microscopy. What are they?
Karyolysis : basophilia of the chromatin fades (loss of DNA because of enzymatic degradation Pyknosis : irreversible chromatin condensation (shrinking nuclei with increased basophilia Karyorrhexis : fragmentation of the nucleus which will totally disappear in 1-2 days
Apoptosis is a rapid, highly regulated activity that shrinks and eliminates defective and unneeded cells. It results in small membrane -enclosed apoptotic bodies which quickly undergo ______ by neighboring cells. Apoptic cells do not rupture and release their contents!
Phagocytosis
Do apoptosis cells rupture ?
No
and they do not release their content
Which process induces caspase cascade activation?
Apoptosis
Does fragmentation of the nucleus occur in apoptosis ? What about damage to the plasma membrane
yes
no
Does the cell shrink vs swell during apoptosis ?
Shrink
In what process does damage to the plasma membrane occur ?
Necrosis
What is plasma membrane blebbing and in what cell death process does it occur ?
Molecules such as phosphatidylserine translocate from the cytoplasmic surface to the outer surface of the membrane. This changes the physical property of the membrane.
What is the role of SMAC/Diablo and cytochrome C ?
What is the role of Bcl-2 family of proteins
•The B-cell lymphoma 2 (Bcl-2) family consist of a_nti-apoptotic and pro-apoptotic members_. It is the most important protein family that regulates apopotosis.
It regulates the release of death promoting factors from mitochondria, activated by either external signal or irreversible internal damage.
Bcl-2 proteins induce a process with the following features :
.
Loss of mitochondrial function and caspase activation
Fragmentation of DNA
Shrinkage of nuclear and cell volumes
Formation and phagocytic removal
Cell membrane changes such as ‘’blebbing’’
Apoptosis can be triggered by intrinsic or extrinsic pathways. Describe them.
Intrinsic : loss of nutrients, oncogenes, tumor suppressors (p53)
Extrinsic : free radicals, oxidants, UV, cytokines,,,,,
What is the consequence of having more cell division than cell death or the opposite ?
Cell accumulation disorders
- Cancer ; Lupus ; glomerulnoephritis, viral infections..
Cell loss disorders
- AIDS ; Alzheimer’s ; Parkinson’s , aplasic anemia, MI..
True or false. The process of necrosis is irreversible.
False - if the the normal cell just started swelling, it will be able to recover.
Once it has got too swollen though, the membrane will disintegrate and the content will spill. At this point, the process is irriversible.
The decrease in cell volume is due to the shrinking of the cytoplasm in the apoptosis process. In this cas, the cytoplasm gets rearranged parallel to the cell surface.
