Apoptosis

Question 1

What is apoptosis?

Answer 1

Programmed cell death

Biochemical events lead to cell changes and death

These changes include; blebbing,cell shrinkage, nuclear fragmentation

Question 2

Apoptosis aims for…

Answer 2

No inflammation

Intact cell membrane

Single cells/small clusters of cells

Cell shrinkage & convolution

Question 3

What is the intrinsic pathway of apoptosis?

Answer 3

Initiates apoptosis through a diverse array of non-receptor-mediated stimuli that produce intracellular signals that act on targets within the cell

Question 4

Give negative and positive factors of the intrinsic pathway of apoptosis;

Answer 4

Positive- radiation, toxins, hyperthermia, infections, free radicals

Negative- withdrawal of factors, loss of apoptotic suppression

Question 5

What can apolitical proteins cause?

Answer 5

Mitochondrial swelling through the formation of membrane pores

Permeability of the mitochondrial membrane and cause apoptotic effectors to leak out

Question 6

Where does the control and regulation of apoptoc mitochondrial events occur?

Answer 6

Through members of the Bcl-2 family of proteins

Question 7

What is the function of the Bcp-2 family of proteins?

Answer 7

Governs mitochondrial membrane permeability and can be either pro-apoptotic or anti-apoptotic

Question 8

How many genes have been identified in the Bcp-2 family?

Answer 8

25 genes

Question 9

During apoptosis what is released from the mitochondria?

Answer 9

Cytochrome c through the actions of the proteins Bax & bak

Question 10

How is the protein complex apoptosome created?

Answer 10

Cytochrome c binds with apoptic protease activating factor -1(Apaf-1) & ATP

then bind to pro-Caspase-9

Question 11

What are caspases?

Answer 11

Family of protease enzymes playing essential roles in programmed cell death

Question 12

What are apoptotic caspases are subcategorised as?

Answer 12

Initiator caspases

Executioner caspases

Once activated they produce a chain resson activating several other executioner caspases

Question 13

Extrinsic signalling pathways initiate…

Answer 13

Apoptosis involving transmembrane receptor-mediated interactions

Question 14

Two theories of the direct initiation of apoptotic mechanisms in mammals have been suggested;

Answer 14

• TNF-induced model

• Fas-Fas ligand-mediated model

Question 15

Describe the TNF pathway of the extrinsic pathway;

Answer 15

TNFa is a cytokine produced mainly by activated macrophages and is the major extrinsic mediator of apoptosis

Question 16

Most cells in the human body have two receptors for TNF;

Answer 16

TNFR1

TNFR2

Question 17

Give an example of 2 death receptors;

Answer 17

DR4

DR5

these receptors bind to the protein TRAIL and mediate apoptosis

Question 18

When what the term Apoptosis first used?

Answer 18

1972

Question 19

What is the first apoptosis signal?

Answer 19

The fas receptor - transmembrane protein of the TNF family which binds the fas ligand

Question 20

What results in the interaction between Fas and FasL?

Answer 20

Formation of DISC (death inducing signalling complex)

Question 21

Describe what happens in type 1 cells associated with the Fas pathway;

Answer 21

Processed caspase-8 directly activated other members of the caspase family, and triggers the execution of apoptosis of the cell

Question 22

Describe what happens in type 2 cells associated with the Fas pathway;

Answer 22

The Fas disc starts a feedback loop, spirals into increasing release of proapoptic factors from mitochondria and the amplified activation of caspase-8

Question 23

Describe what happens in type 2 cells associated with the Fas pathway;

Answer 23

The Fas disc starts a feedback loop, spirals into increasing release of proapoptic factors from mitochondria and the amplified activation of caspase-8