Week One Flashcards

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1
Q

What is cellular stress response

A

Referred to the complex set of signalling reaction’s in cells ranging from activation of pathways that promote cell survival to eliciting programmed cell death that eliminated damaged cells

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2
Q

What are the three groups of stress

A

Environmental
Physiological
Pathological

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3
Q

What are examples of environmental stress

A

cell surroundings temperature, oxidants, change in concentration of ions outside the cells

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4
Q

What are examples of physiological stress

A

regular life cycle or cell functioning responses to growth factors, hormones (gym workout)

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5
Q

What are examples of pathological stress

A

Associated with many diseases cancer tissues, low ph due to high metabolic rate, fever,diabetes

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6
Q

what is adapative stress response

A

They want to activate specific signaling mechanisms to restore homeostasis choice between cell survival and cell death is a central conceptual point for signaling mechanisms

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7
Q

What is common cell responses

A

There are common cell responses to stress chaperons, global reduction of protein translation, and glycosylation and remodelling cellular cytoskeleton

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8
Q

What are the three common components of adaptive stress response pathways

A

Sensor
Trandcuer
Transcrption factors

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9
Q

What is the sensor

A

Protein that physically interacts with TF in the cytosol under normal conditions and stops it from moving into the nucleus or degrades it so it can not interact with stress sensitive genes

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10
Q

What is the transducer

A

It is an enzymatic protien that is activated by stress and covalently modify the TF/sensor complex which inhibit sensor function the TF then goes into the nucleus which the cell needs the genes for the stress response or apoptosis

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11
Q

What happened with Transgensic mice

A

Delte genes encoding the sensor or the TF compontents demonstrated serious biological consequences

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12
Q

What was found when the genetic information on the sensor was deleted

A

It was leathal in all cases

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13
Q

What does it mean when you knock out the sensor

A

Removes the negative feedback on TF and TF is overexpressed

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14
Q

What happens when you delete only TF

A

Animals can surrvive

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15
Q

What happens when you delete both the sensor and TF

A

It is lethal crosstalk between different signalling pathways

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16
Q

What is a common response of cells to stress

A

Global reduction of protein synthesis helping cells to not waste energy needed to overcome stress

17
Q

What is the mechanisms that leads to the overall decrease in protiein synthesis

A

Phosphorylation of the alpha subunit of elF2 which is induced by stress specefic kinases

18
Q

What is elF2

A

A trimeric GTP-binding protein that delivering initiator methionyl-tRNA to the small 40S ribsomal complex for initation

19
Q

What can bind to the elf2a subunit

A

GDP or GTP

20
Q

What does GTP-elf2 complex bind to

A

Met-tRNAi

21
Q

What is the 43S preinitation complex

A

The elF2 complex that is bound to Mer-tRNAi and associates with the 40S ribosmoal subunit and additional regulatory factors

22
Q

What happens when with stress induced phosphorylation of elF2

A

It lowers general protien translation which allows cells to correct the stress damage and ATF4

23
Q

How is the translation of stress related proteins such as ATF4 is stimulated, while the global protein synthesis is reduced or inhibited

A

Delayed translation reinitation upstream open reading frames

24
Q

What happens in non-stressed conditions

A

Low levels of elF2-P and high levels of elF2-GTP. Ribsome binds to the ATF4 and translation of uORF1 which then initates the next uORF2 which overlaps out of rame with ATF4 it then misses the start codon so you no longer have ATF4

25
Q

What happens during cellular stress

A

More elF2-P low elF2-GtP . Translation initation complex is not assembled. It takes longer for the 40s ribsomal unit to reacuire a new elF2 that you need for uORF2 the ribsome scans pass it that the ATF4 scan past it

26
Q

What is no stress condtions

A

High elf2-GTP Low elF2a-P

27
Q

What is Stress condtions

A

Low elF2-Gtp and High elF2a-P