Cells Alive 6: Cell Death Flashcards

1
Q

Necrosis

A

Non-Programmed cell death, non-physiological process

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2
Q

Apoptosis

A

Programmed Cell Death, Homeostatic mechanism, can also occur as a defence mechanism

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3
Q

Autophagy

A

Survival mechanism that can lead to cell death

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4
Q

What causes Necrosis?

A

Accidental death following an injury such as trauma or lack of blood supply, the cells burst and the release of cell content causes inflammation

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5
Q

How does apoptosis occur?

A

by the process of phagocytosis, it is controlled and there is no inflammation

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6
Q

What proteins break down the cells in apoptosis?

A

Caspases

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7
Q

How does the extrinsic pathway of apoptosis work?

A

Death receptor binds to death ligand, this triggers the activation of caspases and proteins that form the disc complex, caspase 8 triggers caspase 3, 6 and 7

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8
Q

What is DISC?

A

death inducing signalling complex

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9
Q

What is the intrinsic pathway of apoptosis?

A

Signalling/ Trigger occurs from inside the cell, e.g. radiation or toxins to activate caspases

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10
Q

What is a negative signal?

A

Absence of growth factors or hormones or any factor that supresses apoptosis

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11
Q

What is a positive signal?

A

Radiation, Toxins Viral infection (not receptor-mediated)

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12
Q

What does cytochrome C mediate?

A

The production of cast base 9

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13
Q

What is Autophagy?

A

Cell self-eating process, induced by starvation- it degrades cytplamsic constituents and organelles in the lysosome

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14
Q

What is an example of apoptosis?

A

Removal of a tadpoles tail to become a frog

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15
Q

What is the purpose of apoptosis?

A

To destroy cells that represent a threat to the entirety of the organism, e.g cells infected with viruses, cells with DNA damage and potentially cancer cells

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16
Q

What do initiator caspases activate

A

a cascade that activates effector caspases

17
Q

What do effector caspases do?

A

Cleave cellular components, such as the nuclear lamina, activate DNAses and other structural proteins

18
Q

What are some negative signals that trigger the intrinsic pathway?

A

absence of growth factors/ hormones, loss of factors that usually suppress apoptosis

19
Q

What are some positive signals that trigger the intrinsic pathway?

A

Radiation, Toxins, hypoxia
Changes in mitochondrial membrane
2) Opening of the MPT pore
3) Release in the cytoplasm if mitochondrial proteins (e.g. cyt C)
4) Binding of Cyt C to pro-caspase 9 leading to its activation

20
Q

What modulates the events of the intrinsic pathway?

A
  • Bcl2, Bcl-X-anti-apoptotic
  • Bax, Bid, Bad-pro-apoptotic
    They regulate the release of Cyt C from the mitochondria
21
Q

What caspase does the intrinsic pathway activate?

A

Caspase 9

22
Q

How is autophagy different to apoptosis?

A

Has markers, ULK, Beclin, and LC3