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Molecular Basis Of Disease/ Microbiology And Immunology > Cell Death And Cell Damage > Flashcards

Cell Death And Cell Damage Flashcards

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Biology 101 flashcards
1
Q

What is the purpose of necrosis?

A

Removes damaged cells from an organism

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2
Q

Why does necrosis cause acute inflammation?

A

Clear cell debris via phagocytosis

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3
Q

What are the causes of necrosis?

A 
Lack of blood supply as a result of: 
Injury
Infection
Cancer
Infarction
Inflammation
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4
Q

What is the step by step of necrosis?

A

injurious agent or event

  • > lack of oxygen prevents ATP production
  • > cells swell due to influx of water
  • > lysosomes rupture: enzymes degrade other organelles and nuclear material haphazardly
  • > cellular debris is released, triggering inflammation
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5
Q

What are the three changes in the microscopic appearance of necrosis?

A

Nuclear, cytoplasmic and biochemical

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6
Q

What are the nuclear changes that happen in necrosis?

A

Chromatin condensation
Fragmentation of the nucleus
Dissolution of the chromatin by DNAase

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7
Q

What are the cytoplasmic changes that happen in necrosis?

A

Opacification: protein denaturation and aggregation

Complete digestion of cells by enzymes causing cells to liquefy

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8
Q

What are the biochemical changes that happen in necrosis?

A

Release of enzymes such as creatinine kinase or lactate dehydrogenase and other proteins like myoglobin

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9
Q

Why are biochemical changes useful in a clinical setting?

A

Measure the extent of tissue damage

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10
Q

What are the functions of apoptosis?

A

Deletion of superfluous, injected or transformed cells

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11
Q

What is apoptosis involved in?

A 
Embryogenesis
Metamorphosis
Normal tissue turnover
Endocrine-dependent tissue atrophy
Variety of pathological conditions
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12
Q

What is the step by step of apoptosis?

A

Programmed cell death of one or a few cells

  • > cells shrink as the cytoskeleton is disassembled
  • > orderly packaging of organelles and nucelar fragments into membrane bound vesicles
  • > new molecules are expressed on vesicular membranes that stimulate phagocytosis without an inflammatory response
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13
Q

Is necrosis reversible?

A

Initial events are reversible, later ones are not

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14
Q

Is apoptosis reversible?

A

No

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15
Q

What are the cytoplasmic changes in apoptosis?

A

Shrinkage of cell
organelles packaged into membrane vesicle
Phagocytosis of cell fragments by macrophages and adjacent cells
No leakage of cytosolic components

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16
Q

What are the nuclear changes in apoptosis?

A

Nuclear chromatin condenses on nuclear membranes

DNA cleavage

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17
Q

What are the biochemical changes in apoptosis?

A

Expression of charged sugar molecules on the outer surface of cell membranes
Protein cleavage by proteases

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18
Q

What are the two types of apoptosis?

A

Intrinsic and extrinsic

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19
Q

What causes intrinsic apoptosis (specifically)?

A 
DNA damage
interruption of the cell cycle
Inhibition of protein synthesis
Viral infection
Change in redox state
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20
Q

What causes extrinsic apoptosis?

A

Survival factors
Extracellular signals
Tcell or natural killer

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21
Q

What are caspases?

A

Cysteine proteases

22
Q

What is the caspase cascade?

A

Initiator caspases (8 and 9) activate other caspases which both cleave cytosolic proteins and activate more proteases which also cleave nuclear lamin

23
Q

What are the effects of caspase activation?

A 
Morphological changes: 
Shrinkage
Chromatin condensation
DNA fragmentation 
plasma membrane blebbing
24
Q

What do initiator caspases do?

A

Activate themselves when in close proximity

25
Q

What is extrinsic apoptosis induced by?

A

Ligand binding to receptors, causing receptor dimer(or multimer)isation

26
Q

What are involved in ligand induced multimerisation?

A

Ligand
Receptor
Death adaptor
Procaspase-8

27
Q

Which parts of ligand induced multimerisation share a death domain?

A

Receptor and death adaptor

28
Q

Which parts of ligand induced multimerisation share the death effector domain?

A

Death adaptor and procaspase-8

29
Q

What is an example of ligand induced multimerisation?

A

Tumour necrosis factor (TNF)

30
Q

What does TNF do?

A

Binds to TNFreceptor - creates an environment for oligomerisation with other death domains
Causes FADD binding which forms an environment with a high concentration of death effector domain
Causes procaspase-8 binding
Causes autoproteolysis, activating the caspase and initiating the caspase cascade

31
Q

What is intrinsic apoptosis induced by?

A

Cytochrome C release from the mitochondria

32
Q

What does FADD stand for?

A

FAS- associated protein with death domain

33
Q

What is cytochrome C?

A

Mitochondrial matrix protein

34
Q

What is involved in cytochrome C induced apoptosis?

A

Cytochrome C, APAF-1, procaspase-9

35
Q

What does APAF-1 stand for?

A

Apoptotic protease activating factor

36
Q

What is APAF-1 made up of?

A

Cytochrome C binding site
APAF domain
Caspase recruitment domain

37
Q

What is procaspase-9 made up of?

A

Caspase recruitment domain and protease domain

38
Q

What is an apoptosome?

A

The whole cytochrome C induced apoptosis complex

39
Q

How is the mitochondrial release of Cytochrome C regulated?

A

BCL-2 family protein pore

40
Q

Are BCL-2 proteins pro or anti-apoptotic?

A

Can be either

41
Q

What BCL-2 family proteins are anti-apoptotic?

A

BCL-2, BCL (and more!)

42
Q

What is the job of anti-apoptotic BCL-2 proteins?

A

Repress cytochromes

43
Q

Which of the BCL-2 family are pro-apoptotic?

A

BAX, BID, BAD etc

44
Q

What is the function of pro-apoptotic BCL-2 proteins?

A

Facilitate cytochrome C release

45
Q

What is the BH3 domain used for?

A

To allow the BCL-2 family proteins to form dimers

46
Q

What regulates BCL-2 proteins?

A

TP53, growth factors

47
Q

How does TP53 regulate BCL-2 proteins?

A

Increases BAX, so more membrane pore insertion

  • > not enough BCL-2 to block the channels
  • > cytochrome c is released
  • > cell death
48
Q

How do growth factors regulate BCL-2 proteins?

A

Activate PKB, which phosphorylates BAD

  • > phosphorylated BAD can’t bind to BCL-2 so cytochrome c isn’t released
  • > cell survives
49
Q

What happens if only BAX is present?

A

Cytochrome C is released

50
Q

What happens if BAX and BCL-2 is released?

A

Cytochrome C remains in the mitochondria

Molecular Basis Of Disease/ Microbiology And Immunology (57 decks)

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