Lecture 22: Apoptosis Flashcards

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1
Q

What is apoptosis?

A

Programmed cell death

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2
Q

What is tissue homeostasis?

A

Maintaining a balance between proliferation and cell death

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3
Q

What are some ways apoptosis is used in the body?

A

Nervous system to match the number of nerve cells to target cells
Immune system in clonal selection

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4
Q

What are some features of normal homeostasis?

A

Responsible of elimination of cells in embryonic development
Cell turnover in healthy adult tissues
Physiological involution and atrophy of tissues

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5
Q

What are some features of pathological apoptosis?

A

Can be triggered by tissues
Spontaneous in untreated cancer
Contributes to chemotherapy induced tumour regression

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6
Q

How does the intrinsic apoptosis pathway occur?

A

Using internal stress

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7
Q

How does the extrinsic apoptosis pathway occur?

A

Using external signals

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8
Q

What is the process of cytochrome c release in the intrinsic apoptosis pathway?

A
  1. CC released from mitochondria into cytosol
  2. Membrane asymmetry lost so internal marker externalised
  3. Membrane integrity lost so DNA dye enters cell
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9
Q

What is the process of downstream events and caspase activation in the intrinsic apoptosis pathway?

A
  1. Cytochrome release
  2. Apoptosome assembly
  3. Caspase activation
  4. Proteolysis of substrates
  5. DNA digestion
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10
Q

What is the main premise of upstream events in intrinsic apoptosis?

A

Controlling the pore

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11
Q

What do pro death factors aim to do in intrinsic apoptosis?

A

Open the pore

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12
Q

What do pro survival factors aim to do in intrinsic apoptosis?

A

Keep pore closed

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13
Q

What is the Bcl-xL inhibitor?

A

It suppresses the pro survival function
The pore is more likely to stay open

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14
Q

What does the Bcl-xL inhibitor do in relation to chemotherapy?

A

It sensitises cancer cells to taxol-induced apoptosis

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15
Q

What is the process of elimination of T cells recognising self antigens? (EXTRINSIC)

A
  1. T cells recognising self antigens must be eliminated
  2. T cell binds to APC expressing self and FasL is expressed
  3. FasL binds to Fas receptor
  4. Apoptosis
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16
Q

What occurs when there are defects in the Fas pathway?

A

Autoimmune syndrome