Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOC 341 > Lecture 22: Apoptosis-programmed cell death > Flashcards

Lecture 22: Apoptosis-programmed cell death Flashcards

1
Q

Programmed Cell Death

A

• Programmed cell death is a vital process to the overall good of a multicellular organism

  • Apoptosis is one form of programmed cell death
  • Up to half of the neurons in a developing vertebrate organism die soon after they are formed (target selection)
  • Some tissues are formed and most are maintained at a consistent size by selective apoptosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Morphological changes during apoptosis

A
  • Cells shrink in size
  • Chromatin condenses and fragments
  • The cytoskeleton disassembles
  • The nuclear envelope collapses
  • The cell surface distends or “blebs”
  • The plasma membrane is chemically altered to promote phagocytosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

____ results from acute injury and the cells typically swell and burst causing an inflammatory response.

A

Cell necrosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

_____ are essentially degraded from the inside out without damage to neighboring cells

A

Apoptotic cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Cell death is induced by the absence or low amounts of “_______”

A

survival factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Biochemical changes associated with apoptosis

A
  • DNA fragmentation
  • Loss of phospholipid asymmetry in the plasma membrane.

– Phosphatidylserine flips to the outer leaflet

  • Cell surface modifications that promote phagocytosis
  • Loss of Proton Motive force in mitochondria
  • Some of these changes can be detected in dying cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

_____ that are activated as a result of apoptosis cut genomic DNA into a characteristic ladder patterns due to cleavage in the linker regions between nucleosomes

A

Endonucleases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does the TUNEL assay detect apoptosis?

A

The newly generated DNA ends that result from genomic cleavage can be detected in cells by modifying the ends of DNA with a fluorescent nucleotide.

TUNEL=TdT mediated dUTP nick end labeling

TdT=terminal deoxynucleotide transferase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

____ is responsible for the apoptosis that is involved in limb formation

A

BMP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The primary mechanism of destruction is the activation of proteases called ____ (active site cys, cleave at specific asp residues)

A

caspases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Not all caspases are involved in apoptosis, some are important for the _____

A

inflammatory response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

An activation cascade is thought to be set in motion by _____ that are activated in response to a signal through their _____.

A

initiator caspases

caspase recruitment domain (CARD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Once activated, these initiator caspases propagate the cascade of activation through ______

A

executioner caspases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Caspases involved in inflamation

A

– Caspase 1 (Interleukin-1 converting enzyme, ICE), 2, 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Initiator caspases

A

– Extrinsic pathway

• Caspases 8, 10

– Intrinsic pathway

• Caspases 2, 9

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Executioner Caspases

A

– Caspases 3, 6, and 7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Activation of Caspases

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Caspase Cascade

A
19
Q

How do caspases trigger DNA fragmentation

A

-executioner caspases cleave iCAD, cleave iCAD releases CAD which cuts DNA between nucleosomes

20
Q

Extrinsic pathway

A

– Activation of Cell surface receptors (death receptors)

21
Q

Intrinsic pathway

A

– Triggered in response to injury or stress

– DNA damage

– Lack of oxygen, nutrients, or survival signals

22
Q

Extrinsic pathway of Apoptosis

A
  • Cell surface receptors (death receptors) activate the extrinsic pathway
  • Single span membrane proteins with an extracellular ligand binding domain and an intracellular death domain
  • Receptors are homotrimers of the tumor necrosis factor (TNF) family
  • Includes the TNF receptors itself and the Fas death receptor
23
Q

Induction of apoptosis by extracellular stimuli

A

Extrinsic pathway by activation of Fas death receptors

24
Q

Intrinsic Pathway of Apoptosis

A
  • Depends on the release of mitochondrial intermembrane space proteins into the cytosol
  • The release of cytochrome c, the electron carrier between ETS complex III and cytochrome oxidase, can trigger apoptosis
  • Released cytochrome c binds to a procaspase activating adapter called Apaf-1 (apoptotic protease activating factor), driving its oligomerization into a wheel like heptamer called the apoptosome
  • The aggregated Apaf-1 binds and activates caspase-9 by induced proximity
  • This initiator caspase-9 activates downstream executioner caspases
25
Q

Induction of apoptosis by intracellular stimuli

A
26
Q

_____ proteins control the release of cytochrome c from mitochondria

A

Bcl-2 (B-cell lymphoma-2)

27
Q

_____ inhibit apoptosis (anti-apoptotic)

A

(Bcl-2 and BclXL)

28
Q

Other family members _____ promote apoptosis (pro-apoptotic)by increasing cytochrome c release from mitochondria.

A

(Bax and Bac)

29
Q

anti-apoptotic Bcl2 family proteins have:

A

all 4 BH domains

30
Q

pro-apoptotic Bcl2 family proteins have

A

BH 1-3 domains

31
Q

BH3 only pro-apoptotic proteins include:

A

Bad, Bim, Bid, Puma, Noxa

32
Q

___ is tightly bound to the mitochondrial membrane even in the absence of an apoptotic signal

A

Bak

33
Q

___ is mainly located in the cytosol an translocates to the mitochondria in response to an apoptotic signal

A

Bax

34
Q

Upon activation, Bax and Bak generate….

A

pore-forming proteins in the mitochondrial outer membrane

35
Q

Bcl2 mechanism of cytochrome C release

A
36
Q

Bcl-2 and Bcl-XL

A

• Located on the cytosolic surface of the mitochondrial outer membrane

• Binds to bax to prevent bax oligomerization

37
Q

BH3 only proteins

A
  • proapoptotic
  • Binds to Bcl2 to inhibit their ability to bind and inhibit Bak or Bax
38
Q

____ is transcriptionally upregulated in the absence of cell survival signals

A

Bim

39
Q

___ and ___ are transcriptionally upregulated in response to DNA damage

A

Puma and Noxa

40
Q

Bid is cleaved to tBid by activated ___ coordinating the extrinsic and intrinisic pathways in some cells

A

caspase 8

41
Q

Inhibitors of Apoptosis (IAPs)

A

• Caspase inhibitors

  • Used by viruses to prevent the host cell form committing suicide prior to viral replication
  • IAPs can be countered by anti-IAPs in some cells
  • Anti-IAPs bind to IAP and prevent them from inhibiting caspase
  • Genetic manipulation of IAP or anti-IAPs have dire consequneces in flies indicating the delicate balance needed for apoptosis during development
42
Q

Three methods of survival factor inhibition of apoptosis

A
  1. increased production of anti-apoptotic Bcl2 family protein
  2. inactivation of pro-apoptotic BH3-only protein
  3. inactivation of anti-IAPs
43
Q

Apoptotic cells are cleared by ____

A

phagocytosis

BIOC 341 (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions