Apoptosis: Mechanisms and Regulation in Cell Biology

Question 1

What is a defining characteristic of apoptosis?

Accepted Answer

Programmed and controlled cell death

Answer

Uncontrolled release of cellular contents

Answer

Absence of caspase activation

Answer

Lack of mitochondrial involvement

Question 2

How do the different members of the Bcl-2 family of proteins influence the cell's decision between survival and apoptosis?

Accepted Answer

Pro-apoptotic members trigger apoptosis by activating caspases, while anti-apoptotic members prevent apoptosis by binding to and neutralizing pro-apoptotic members.

Answer

Both pro- and anti-apoptotic members trigger apoptosis by activating caspases.

Answer

Both pro- and anti-apoptotic members prevent apoptosis by binding to and neutralizing caspases.

Answer

Pro-apoptotic members prevent apoptosis by binding to and neutralizing anti-apoptotic members.

Question 3

Which of the following is NOT a characteristic of apoptosis?

Accepted Answer

Increased cell proliferation

Answer

Cell shrinkage

Answer

DNA fragmentation

Answer

Mitochondrial swelling

Question 4

Which caspase is known as the 'executioner caspase' and is responsible for cleaving vital cellular proteins?

Accepted Answer

Caspase-3

Answer

Caspase-8

Answer

Caspase-9

Answer

Caspase-10

Question 5

Which Bcl-2 family member is anti-apoptotic and inhibits the release of cytochrome c from mitochondria?

Accepted Answer

Bcl-2

Answer

Bax

Answer

Bad

Answer

Bak

Question 6

Which of the following is a trigger for the intrinsic pathway of apoptosis?

Accepted Answer

Mitochondrial dysfunction

Answer

DNA damage

Answer

Fas ligand binding

Answer

TNF-alpha signaling

Question 7

What is the role of the death receptor in the extrinsic pathway of apoptosis?

Accepted Answer

Binds to ligands and triggers caspase activation

Answer

Releases cytochrome c from mitochondria

Answer

Activates the JNK signaling pathway

Answer

Inhibits caspase activity

Question 8

Which characteristic is NOT associated with apoptosis?

Accepted Answer

Necrosis

Answer

Energy-dependent process

Answer

Programmed cell death

Answer

Chromatin condensation

Question 9

Which enzyme family is central to the execution phase of apoptosis?

Accepted Answer

Caspases

Answer

Proteases

Answer

Kinases

Answer

Phosphatases

Question 10

Which member of the Bcl-2 family promotes apoptosis?

Accepted Answer

Bax

Answer

Bcl-2

Answer

Bcl-xL

Answer

Mcl-1

Question 11

Which molecule is a key regulator of the extrinsic pathway of apoptosis?

Accepted Answer

TNF-alpha

Answer

Bax

Answer

Cytochrome c

Answer

Caspase-3

Question 12

What is the function of FLIP in apoptosis?

Accepted Answer

Inhibiting apoptosis

Answer

Promoting apoptosis

Answer

Activating caspases

Answer

Degrading cytochrome c

Question 13

What is the role of phagocytes in apoptosis?

Accepted Answer

Removing apoptotic cells

Answer

Activating caspases

Answer

Inhibiting apoptosis

Answer

Releasing cytochrome c

Question 14

How do cellular signaling pathways regulate apoptosis to maintain tissue balance and prevent uncontrolled cell growth?

Accepted Answer

Cellular signaling pathways can trigger or block apoptosis based on the cellular context.

Answer

Apoptosis occurs independently of cellular signaling pathways.

Answer

Apoptosis is always advantageous to the organism.

Answer

Apoptosis pathways are independent of cell cycle regulation.

Question 15

Discuss the mechanisms of action of cellular inhibitors, such as FLIP and IAPs, in regulating apoptosis. Describe their potential implications for therapeutic interventions.

Accepted Answer

FLIP inhibits caspase-8 and IAPs inhibit caspase-9, effectively blocking the apoptotic cascade.

Answer

FLIP and IAPs activate caspases, leading to increased apoptosis.

Answer

FLIP and IAPs regulate apoptosis by modulating mitochondrial permeability.

Answer

FLIP and IAPs are not involved in apoptosis regulation.

Question 16

Which enzyme family is essential for the execution phase of apoptosis?

Accepted Answer

Caspases

Answer

Kinases

Answer

Proteases

Answer

Phosphatases

Question 17

Which of the following is a pro-apoptotic Bcl-2 family member?

Accepted Answer

Bak

Answer

Bcl-2

Answer

Bcl-xL

Answer

Bcl-w

Question 18

Which of the following is NOT a regulator of apoptosis?

Accepted Answer

TGF-alpha

Answer

p53

Answer

TRAIL

Answer

c-FLIP

Question 19

Which of the following is NOT a characteristic of apoptosis?

Accepted Answer

Characterized by uncontrolled cell rupture

Answer

Programmed cell death

Answer

Orchestrated cellular dismantling

Answer

Involves engulfment by phagocytes

Question 20

Which enzyme family is crucial in the execution phase of apoptosis?

Accepted Answer

Caspases

Answer

Kinases

Answer

Proteases

Answer

Ligases

Question 21

Which protein from the Bcl-2 family promotes apoptosis?

Accepted Answer

Bak

Answer

Bcl-2

Answer

Bcl-xL

Answer

Mcl-1

Question 22

Which of the following is characteristic of the extrinsic pathway of apoptosis?

Accepted Answer

Ligand binding to death receptors

Answer

Initiated by caspase activation

Answer

Independent of mitochondrial events

Answer

Requires the presence of cytochrome c

Question 23

What is the primary role of IAPs (Inhibitors of Apoptosis Proteins) in apoptosis regulation?

Accepted Answer

Block caspases and prevent cell death

Answer

Activate caspases and trigger cell death

Answer

Bind to Smac/DIABLO and prevent its release

Answer

Interfere with the formation of the apoptosome

Question 24

Which of the following consequences is associated with the activation of PARP-1 (Poly(ADP-ribose) polymerase-1) during apoptosis?

Accepted Answer

Energy depletion

Answer

DNA repair

Answer

Cell cycle arrest

Answer

Caspase inhibition

Question 25

Which Bcl-2 family protein functions primarily as an anti-apoptotic factor?

Accepted Answer

Bcl-2

Answer

Bax

Answer

Bak

Answer

Bim

Question 26

What process results in the characteristic ladder-like pattern of fragmented genomic DNA observed during apoptosis?

Accepted Answer

DNA laddering

Answer

DNA translation

Answer

DNA methylation

Answer

DNA replication

Question 27

During apoptosis, what is the function of phosphatidylserine translocation to the outer leaflet of the plasma membrane?

Accepted Answer

Marking the cell for recognition and phagocytosis

Answer

Maintaining cell membrane integrity

Answer

Inhibiting death receptor signaling

Answer

Activating caspases

Question 28

Which molecule released from mitochondria during intrinsic apoptosis is a potent activator of apoptosomes?

Accepted Answer

Cytochrome c

Answer

Smac/DIABLO

Answer

XIAP

Answer

Bcl-2

Question 29

What is a central role of Bcl-2 family proteins in apoptosis?

Accepted Answer

Regulating the permeability of the mitochondrial outer membrane

Answer

DNA repair

Answer

Protein synthesis

Question 30

Which of the following is the primary initiating event of the intrinsic apoptosis pathway?

Accepted Answer

Cytochrome c release from mitochondria

Answer

Caspase-3 activation

Answer

TNF-alpha secretion

Answer

Fas ligand binding

Question 31

Which of the following proteins is a member of the Bcl-2 family that promotes apoptosis?

Accepted Answer

Bax

Answer

Survivin

Answer

Mcl-1

Answer

Bcl-2

Question 32

Which of the following caspases is a key executioner caspase in apoptosis?

Accepted Answer

Caspase-3

Answer

Caspase-8

Answer

Caspase-9

Answer

Caspase-12

Question 33

What is the primary function of the death receptor pathway in apoptosis?

Accepted Answer

To initiate the extrinsic apoptosis pathway

Answer

To release cytochrome c from mitochondria

Answer

To activate caspase-3

Answer

To inhibit the Bcl-2 family of proteins

Question 34

Which of the following is a morphological characteristic of apoptosis?

Accepted Answer

Cell shrinkage and membrane blebbing

Answer

Increased protein synthesis

Answer

DNA replication

Answer

Cell cycle arrest

Question 35

What is the main function of the protein p53 in apoptosis?

Accepted Answer

To promote apoptosis in response to cellular stress

Answer

To activate caspases

Answer

To release cytochrome c from mitochondria

Answer

To inhibit apoptosis in response to growth factor deprivation

Question 36

What is the fundamental difference between apoptosis and necrosis?

Accepted Answer

Apoptosis is a regulated and controlled form of cell death, while necrosis is an uncontrolled form.

Answer

Apoptosis occurs in response to external stimuli, while necrosis occurs in response to internal stimuli.

Answer

Apoptosis results in cell shrinkage, while necrosis results in cell swelling.

Question 37

Which of the following is NOT a characteristic of apoptosis?

Accepted Answer

Involves rupture of the cell membrane

Answer

Cell membrane remains intact

Answer

Cells shrink and fragment

Answer

Nucleus condenses

Question 38

Which of the following is a key initiator caspase in the extrinsic pathway of apoptosis?

Accepted Answer

Caspase-8

Answer

Caspase-6

Answer

Caspase-3

Answer

Caspase-9

Question 39

Which of the following proteins is a pro-apoptotic member of the Bcl-2 family?

Accepted Answer

Bax

Answer

Bcl-xL

Answer

Mcl-1

Answer

Bcl-2

Question 40

What is the function of the mitochondrial membrane permeabilization (MMP) pathway in apoptosis?

Accepted Answer

Releases cytochrome c into the cytosol

Answer

Inhibits caspase-3

Answer

Activates caspase-8

Answer

Prevents DNA fragmentation

Question 41

What is the role of the unfolded protein response (UPR) in apoptosis?

Accepted Answer

Can induce apoptosis if stress is prolonged or severe

Answer

Always inhibits apoptosis

Answer

Prevents protein misfolding

Answer

Activates caspase-3

Question 42

What is the primary role of the apoptotic body?

Accepted Answer

Removal of apoptotic cell remnants by phagocytes

Answer

Prevention of secondary necrosis

Answer

Initiation of caspase-3 activation

Answer

Activation of the immune response

Question 43

Which molecule, released from the mitochondria, is a crucial trigger for the intrinsic apoptosis pathway?

Accepted Answer

Cytochrome c

Answer

Fas ligand

Answer

Bcl-2

Answer

TNF-alpha

Question 44

What is the primary function of caspases during apoptosis?

Accepted Answer

Break down cellular components by proteolytic cleavage

Answer

Permeabilize the mitochondrial outer membrane

Answer

Inhibit anti-apoptotic proteins

Answer

Initiate DNA fragmentation

Question 45

Which Bcl-2 family protein promotes apoptosis by increasing mitochondrial permeability?

Accepted Answer

Bax

Answer

Bcl-XL

Answer

Bcl-2

Answer

Mcl-1

Question 46

What is the primary role of inhibitor of apoptosis proteins (IAPs) in apoptosis regulation?

Accepted Answer

Directly inhibit caspase activity

Answer

Trigger DNA fragmentation

Answer

Promote mitochondrial outer membrane permeabilization

Answer

Activate caspases

Question 47

What is a potential consequence of excessive apoptosis?

Accepted Answer

Tissue atrophy

Answer

Tumor development

Answer

Autoimmune disorders

Answer

Tissue hyperplasia

Question 48

Which of the following represents a potential therapeutic application of inducing apoptosis?

Accepted Answer

Cancer treatment

Answer

Wound healing

Answer

None of the above

Answer

Immunosuppression

Question 49

How does the endoplasmic reticulum (ER) contribute to apoptosis?

Accepted Answer

ER stress can trigger the unfolded protein response, which can lead to caspase activation and apoptosis

Answer

Synthesizes apoptotic proteins and releases death receptors

Answer

Releases cytochrome c and induces mitochondrial outer membrane permeabilization

Question 50

Which of the following is NOT a characteristic of apoptosis?

Accepted Answer

Cell swelling and bursting

Answer

DNA fragmentation into nucleosomal units

Answer

Formation of apoptotic bodies, membrane-bound vesicles containing cellular debris

Answer

Activation of caspases, a family of proteases

Question 51

The intrinsic pathway of apoptosis is primarily initiated by:

Accepted Answer

Mitochondrial dysfunction, leading to the release of cytochrome c

Answer

Release of lysosomal enzymes, which can trigger cell death in some cases but are not the primary trigger for intrinsic apoptosis

Answer

Activation of granzyme B, a serine protease released by cytotoxic T lymphocytes

Answer

Binding of death receptors, such as TNF receptor 1, to their ligands

Question 52

Which family of proteins plays a central role in regulating the intrinsic pathway of apoptosis?

Accepted Answer

Bcl-2 family

Answer

TNF receptor family, involved in the extrinsic pathway of apoptosis

Answer

NF-κB family, involved in inflammation and immune responses

Answer

MAPK family, primarily involved in signal transduction pathways

Question 53

What is the primary function of caspases in apoptosis?

Accepted Answer

Degradation of cellular proteins, dismantling the cell in a controlled manner

Answer

Synthesis of new proteins, a process that is downregulated during apoptosis

Answer

Activation of DNA repair mechanisms, a process separate from apoptosis

Answer

Induction of cell cycle arrest, a mechanism of temporary growth stoppage, not the primary function of caspases

Question 54

A mutation in the gene encoding Bax, a pro-apoptotic member of the Bcl-2 family, would most likely lead to:

Accepted Answer

Increased cell survival, as Bax promotes apoptosis and its dysfunction inhibits the process

Answer

Induction of necrosis, a form of cell death distinct from apoptosis

Answer

Increased susceptibility to apoptosis, the opposite of the expected outcome

Answer

No change in cell fate, as Bax plays a significant role in apoptosis regulation

Question 55

A patient presents with a genetic disorder characterized by increased resistance to apoptosis. Which of the following conditions might they be predisposed to?

Accepted Answer

Cancer, as uncontrolled cell proliferation can occur due to failure to eliminate damaged or abnormal cells

Answer

Viral infection,  apoptosis is a mechanism to control viral spread, not a cause of increased susceptibility

Answer

Autoimmune disease,  apoptosis is involved in immune tolerance, not a direct consequence of resistance

Answer

Neurodegenerative disease,  apoptosis is often implicated in neurodegenerative diseases, not a consequence of resistance

Question 56

Which of the following is an example of a protein that can inhibit apoptosis?

Accepted Answer

Bcl-2

Answer

Cytochrome c, a mitochondrial protein that promotes apoptosis

Answer

Caspase-3, an executioner caspase involved in apoptosis

Answer

Bax, a pro-apoptotic protein

Question 57

A researcher is studying a new drug that promotes apoptosis in cancer cells. What is the most likely mechanism of action of this drug?

Accepted Answer

Activation of pro-apoptotic proteins and inhibition of anti-apoptotic proteins, leading to a shift towards apoptosis

Answer

Inhibition of protein synthesis, which could have a general cytotoxic effect but not specifically target apoptosis

Answer

Induction of DNA replication, a process that would promote cell growth, not apoptosis