Apoptosis

Question 1

What is apoptosis? where is it observed?

Answer 1

• 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

Question 2

what is active cell suicide ?

Answer 2

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

Question 3

why is there a need to get rid of cells?

Answer 3

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!)

Question 4

programmed cell death is required for the normal pathology of diseases?

Answer 4

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

Question 5

What is programmed cell death ? where is it observed in?

Answer 5

• 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

Question 6

What is the difference Apoptosis and Necrosis?

Answer 6

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

Question 7

What are types of cell death ?

Answer 7

Programmed cell death

• apoptosis
• Autophagy

Unprogrammed Cell death
- necrosis

Question 8

What is Necrosis ?

Answer 8

• cell injury resulting in premature death of the cell.

Question 9

what the morphological features of apoptosis?

Answer 9

• 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’

Question 10

Purposes of clearing apoptotic cells?

Answer 10

• recycle cellular contents
• prevent release of potential toxic intracellular contents into the medium
• modulate the immune system
• insure that the death program gets completed

Question 11

Biochemical features of apoptosis?

Answer 11

• 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.

Question 12

What is a scramblase?

Answer 12

• Scramblases- is a protein responsible for the translocation of phospholipid

Question 13

What are flippases?

Answer 13

Scramblases are members of the general family of transmembrane lipid transporters known as flippases.

Question 14

What effect does PS (phosphatidylserine) have on apoptosis?

Answer 14

phosphatidylserine (PS) exposure during apoptosis requires inhibition of Flippase(s) and activation of Scramblase(s)

Question 15

How does protein cleavage during apoptosis work?

Answer 15

• protein cleavage during apoptosis is specific and selective ( cleavage is causes by caspases- cysteine proteases that play essential roles in apoptosis, necrosis, and inflammation. )

Question 16

What do we know about programmed cell death during C.Elegans development?

Answer 16

in this experiment all the timings and identity of cell deaths are known

• programmed cell deaths are seen in many different cell types (e.g. neurons , muscle and hypoderms)
• programmed cell death

in an experiment the results:
- ced -3 , 4 promote cell death , ced-9- promotes cell survival

Question 17

What are the stages of apoptosis?

Answer 17

-living cell - then living cell destined to die - excretion - apoptotic cell recognition - phagocytosis - degregation

Question 18

How do engulfment genes work?

Answer 18

-they act into redudant , partially overlapping pathways.

Question 19

What is P53?

Answer 19

• The P53 is a trancription factor mutated in more than 50% of all cancer cells.

Question 20

What does beth and aimee do when in the library ?

Answer 20

A. listen to christmas music
B. eat lots of great snacks and muffins
C. apoptose….
D. all of the above !!!