Cell death

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What are examples of cell death?
necrosis- accidental death following acute insult-trauma cells swell and burst, contents release causes inflammation

programmed cell death eg. apoptosis cells die in organised way and are engulfed and digested, requires ATP, no inflammation
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What is neurodegeneration?
when cells die when they are not supposed to eg. some drugs can induce cell death when they are not meant to die
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Why is programmed cell death needed?
-essential for proper development as mitosis: cells of the tail in tadpole need to die by apoptosis to make the tail disappear. Removal of interdigital webs undergoes apoptosis during limb development.
-brain formation- surplas cells be eliminated by apop
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What are features of apoptosis?
-cell surface has a bleb appearance
-shrinkage of cell and nucleus
-cleavage of nuclear proteins
-cleavage of nuclear DNA
-condensation of chromatin
-nucleus fragmentation
-cleavage of cytoskeleton
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Why does a ladder shape appear during apoptosis?
The DNA is being cleaved in the internucleosomal place. The protein that is cleaving the DNA strand is cutting the DNA in between nucleosomes with a distance cut of 200 BP as approximately 200 BP around histone
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What are on the outside of cells which attracts macrophages?
signals and this causes it to be engulfed
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What are caspases?
key proteins for cellular destruction. They are cell death proteases
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What are caspases called when usually inactive on a cell?
procaspases
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Why dont we want caspases activated on a cell?
as it will cause the cell to die
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What are caspases activated by?
cleavage
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What happens once they are activated?
small numbers of initiator caspase activates a cascade which generates lots of effector caspases
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What do effector caspases do?
they cleave cellular components like the nuclear lamina, activate DNases and other structural proteins. Now activation of capsases are complete and are irreversible
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Once procaspases are activated by cleavage what happens?
there will be cleavage sites in the protein
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What are the two pathways that cell death can occur from?
intrinsic pathway which happens inside the cell and extrinsic pathway which happens outside the cell
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What happens in intrinsic pathway?
-It is switched on by stress and damaged mitochondria releases cytochrome c -electron carrier
-cytochrome c in the cytoplasm activates one of the initiator caspases which activates the cascade
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What happens in extrinsic pathway?
proteins from other cells bind to death receptors on the cell surface and they aggregate and cause caspase 9 to be cleaved which activates the cascade
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Other cards in this set

Card 2

Front

What is neurodegeneration?

Back

when cells die when they are not supposed to eg. some drugs can induce cell death when they are not meant to die

Card 3

Front

Why is programmed cell death needed?

Back

Preview of the front of card 3

Card 4

Front

What are features of apoptosis?

Back

Preview of the front of card 4

Card 5

Front

Why does a ladder shape appear during apoptosis?

Back

Preview of the front of card 5
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