Types of apoptosis: programmed cell death

Question 1

What is apoptosis?

Answer 1

Regulated programmed cell death

Question 2

What are the 2 types of apoptosis?

Answer 2

Pathological, physiological

Question 3

What happens to cell size in apoptosis?

Answer 3

Shrinkage

Question 4

What happens to the nucleus in apoptosis?

Answer 4

Becomes fragmented

Question 5

Give 2 ways in which apoptosis is different from necrosis?

Answer 5

Apoptosis doesn’t trigger inflammatory response

Apoptosis keeps membrane integrity intact

Question 5

Are cell membranes affected in apoptosis?

Answer 5

Membranes remain intact

Question 6

Why does apoptosis occur during the menstrual cycle?

Answer 6

Endometrium breakdown in response to hormone withdrawal

Question 7

Give 2 reasons why lymphocytes undergo apoptosis in germinal centres?

Answer 7

They fail to express useful antigen receptors, or target ‘self’

Question 8

How can genotoxic stress trigger apoptosis in 2 ways?

Answer 8

DNA repair mechanisms fail, so apoptosis occurs to prevent malignancy development

Dysfunctional p53 tumour suppressor gene causes DNA damage that triggers apoptosis

Question 9

How can ER trigger apoptosis?

Answer 9

Misfolded proteins accumulate in ER, causing stress

Question 10

What 3 stimuli trigger the intrinsic/mitochondrial pathway?

Answer 10

Cell injury, DNA damage, loss of hormone stimulation

Question 11

In the intrinsic/mitochondrial pathway, what anti-apoptotic molecule is inactivated?

Answer 11

BCL-2

Question 12

In the intrinsic/mitochondrial pathway, what does the inactivation of BCL-2 stimulate?

Answer 12

Cytochrome C leaks from inner mitochondrial matrix into cell cytoplasm

Question 13

In the intrinsic/mitochondrial pathway, what does cytochrome C activate?

Answer 13

Initiator then executioner Caspases (proteases that break down cell proteins)

Question 14

In the extrinsic/death receptor initiated pathway, what activates caspases?

Answer 14

FAS ligand binds to FAS death receptor on target cell

Question 15

What kind of lymphocytes activate the extrinsic/death receptor initiated pathway?

Answer 15

Lymphocytes that respond to ‘self’

Question 16

How can Tumour Necrosis Factor activate the extrinsic/death receptor initiated pathway?

Answer 16

TNF binds to TNF receptor on target cell

Question 17

What molecule do viruses and normal cells produce that blocks apoptosis, and what specific molecule is blocked?

Answer 17

FLIP blocks enzyme pro-caspase 8

Question 18

In apoptotic cells, how does the plasma membrane change so that it is recognised by macrophages?

Answer 18

Phosphatidylserine flips to face outwards

Question 19

What do apoptotic cells secrete to recruit macrophages?

Answer 19

Soluble factors

Question 20

What 2 substances coat/bind apoptotic cells to attract macrophages?

Answer 20

Coated by thrombospondin, bind to C1q

Question 21

How are apoptotic bodies formed, and what do they become ligands of?

Answer 21

Form from cytoskeleton and nucleus after they are degraded by caspases, then become ligands of macrophage receptors

Question 22

What receptor and protein interact in necroptosis?

Answer 22

TNF receptor, Receptor-Interacting Protein (RIP) kinase

Question 23

Does necroptosis have similar features to apoptosis or necrosis?

Answer 23

Both

Question 24

What is pyroptosis?

Answer 24

Cell death with fever/pyrexia, as it is a highly inflammatory form of apoptosis

Question 25

What condition sometimes triggers pyroptosis?

Answer 25

Microbial infection which is associated with fever due to release of IL-2

Question 26

Which cytosolic protein is activated in pyroptosis, which further activates caspases?

Answer 26

Inflammasome: danger-sensing protein

Question 27

What kind of infection can cause cells to be killed directly by apoptosis as well as promoting an immune response?

Answer 27

Viral infection

Question 28

When do T cells cause apoptosis?

Answer 28

Tumour, transplant rejection

Question 29

When duct obstruction occurs, what cells undergo apoptosis?

Answer 29

Atrophic cells