Chapter 3 - Apoptosis - To be continued...

Question 1

T or F: Apoptosis is ATP-dependent process

Answer 1

TRUE

Question 2

Apoptotic changes of a cell:

Answer 2

Cell shrinkage

Chromatin condensation

Membrane blebbing

Question 3

Morphologic features of apoptosis:

Answer 3

Eosinophilic cytoplasm and basophilic nucleus

Pyknosis and karyorrhexis

Question 4

In Apoptosis, the cell membrane typically remains…

Answer 4

Intact, without significant inflammation

Question 5

Sensitive indicator of apoptosis:

Answer 5

DNA laddering (fragments in multiples of 180 bp)

Question 6

Under what conditions does intrinsic (or mitochondrial) apoptosis occur?

Answer 6

Tissue remodeling during embryogenesis and exposure to noxious stimuli (eg, radiation, toxins, hypoxia)

Question 7

Intrinsic Apoptosis Pathway: BAX and BAK are…

Answer 7

Proapoptotic

Question 8

Intrinsic Apoptosis Pathway: Bcl-2 and Bcl-xL are…

Answer 8

Antiapoptotic

Question 9

BAX and BAK: mechanism

Answer 9

Pores in the mitochondrial membrane → release of cytochrome C → activation of caspases

Question 10

Bcl-2: mechanism

Answer 10

Keeps mitochondrial membrane impermeable

Question 11

Bcl-2 overexpression results in…

Answer 11

Tumorigenesis

Question 12

Example of Bcl-2 overexpression

Answer 12

Follicular lymphoma - t[14; 18]

Question 13

Extrinsec Apoptosis Pathway: 2 ways

Answer 13

1. FasL - Fas (CD95) OR TNF-α - receptor

2. T cytotoxic releasing Perforin and Granzyme B

Question 14

Fas-FasL interaction: example

Answer 14

Thymic medullary negative selection

Question 15

Defective Fas-FasL interactions cause…

Answer 15

Autoimmune lymphoproliferative syndrome

Question 16

What is the final common target of the intrinsic and extrinsic pathways of apoptosis?✅

Answer 16

Activation of caspases (cytosolic proteases)

Question 17

What might be seen on DNA gel electrophoresis of a sample containing genetic material from apoptotic cells?✅

Answer 17

Fragments in multiples of 180 bp (DNA laddering)

Question 18

Differentiate between pyknosis and karyorrhexis✅

Answer 18

Pyknosis is nuclear shrinkage; karyorrhexis is nuclear fragmentation by endonuclease action at internucleosomal regions

Question 19

What steps result in the formation of apoptotic bodies after caspase activation?✅

Answer 19

Cellular shrinkage, chromatin condensation, nuclear fragmentation, cytoskeletal dispersion → cytoplasmic bleb → attached with ligands for macrophage cell receptors → apoptotic bodies

Question 20

What is the consequence of Fas mutation in regard to negative selection in the thymus?✅

Answer 20

Increased number of self-reacting lymphocytes due to failure of clonal deletion

Question 21

A decrease in IL-2 after a completed immunologic reaction causes apoptosis of proliferating effector cells through the…

Answer 21

Intrinsic pathway