Apoptosis

Question 1

Define: Necrosis

Answer 1

Cell death that is not part of the program.

The cell death event is catastrophic.

Question 2

List the basic steps of necrosis

Answer 2

1. Swelling begins in the mitochondria
2. The cell can no longer generate ATP b/c the mito cannot maintain ion gradients
3. The plasma membrane’s ion pumps fail and water floods in, cell swells and bursts
4. Pro-inflammatory molecules are released and an immune response occurs

Question 3

Define: Apoptosis

Answer 3

Programmed cell death

Question 4

List the common components of apoptosis

Answer 4

1. Nuclear collapse and loss of cell volume
2. Cleavage of DNA (DSB)
3. “Eat me” signals from PS on the cell surface
4. Cell splits into apoptotic bodies
5. Cell is phagocytosed by macrophages

Question 5

What enzyme moves PS to the outer leaflet of the plasma membrane during PCD?

Answer 5

Scramblase

Question 6

What is the main difference between apoptosis and necrosis?

Answer 6

Apoptotic cells never lose membrane integrity. Therefore they do not release any of their cellular content and do not trigger an immune response

Question 7

How is annexin V used experimentally?

Answer 7

Annexin V binds to PS on the surface of the cell and can be tagged with a fluorescent probe to monitor early apoptotic cells

Question 8

Explain the importance of the discovery that thymocyte apoptosis is inhibited by actinomycin d.

Answer 8

Actinomycin D inhibits transcription. If radiation-induced apoptosis does not occur in the presence of AD then it is not the process of radiation itself that kills the cells. It is that radiation is telling the cell to kill themselves by up regulation of specific proteins involved in apoptosis.

Question 9

What is morphogenetic death?

Answer 9

An apoptotic phenomenon that determines the final shape of body parts and organs
ex. Limb and nervous system development, gut epithelium turn over

Question 10

Every cell division is matched with —-

Answer 10

Cell death. 1:1

Question 11

Autoimmune lymphoproliferative syndrome

Answer 11

Cells divide at the normal rate, but are not undergoing apoptosis correctly.

Mutations in Fas or FasL.

Can be treated with radiation.

Question 12

Caspase 9 is involved with which apoptotic pathway?

Answer 12

Intrinsic.

Question 13

Caspase 8 is involved with which apoptotic pathway?

Answer 13

Extrinsic.

Question 14

What is the role of BCL-2 and BCL-XL?

Answer 14

They guard the mitochondria membrane - anti-apoptotic

Question 15

Pro-apoptotic proteins are…?

Answer 15

Bim, PUMA replace BCL-2 and BCL-XL on the mitochrondria membrane. This allows BAX and BAK to act on the membrane.

Question 16

What molecule is released from the mitochondria during the intrinsic pathway of PCD?

Answer 16

Cytochrome C.

It then activates Apaf-1 to activate cas 9 and downstream cas 3.

Question 17

Cas 9 and cas 8

Answer 17

A signal caspase

Question 18

Cas 3

Answer 18

The executioner caspase

Question 19

What proteins are involved in the extrinsic pathway?

Answer 19

FasL, Fas, FADD, Caspase-8, caspase-3

Question 20

Which cell type is most sensitive to radiation?

Answer 20

Lymphocytes

Question 21

How is FLIP related to caspase-8?

Answer 21

FLIP is proteolytically-inactive and competes with caspase-8 for FADD binding and prevents it’s activation.