Question 1

Which of the following best distinguishes apoptosis from necrosis at the cellular level?

Accepted Answer

Apoptosis is characterized by cell shrinkage, chromatin condensation, and membrane blebbing, while necrosis is characterized by cell swelling and plasma membrane rupture.

Question 2

During embryonic development, apoptosis is crucial for which of the following processes, as shown in the images of developing digits?

Accepted Answer

Removal of webbing between digits to form individual fingers and toes

Question 3

Which of the following steps is required for the activation of initiator caspases during apoptosis?

Accepted Answer

Dimerization and subsequent cleavage of procaspase monomers

Question 4

What is the primary function of executioner caspases in the apoptotic pathway?

Accepted Answer

To cleave a wide variety of cellular proteins, leading to the morphological and biochemical changes seen in apoptosis

Question 5

DNA fragmentation during apoptosis is a result of which molecular event?

Accepted Answer

Activation of CAD (caspase-activated DNase) following cleavage of its inhibitor by executioner caspase-3

Question 6

In the extrinsic pathway of apoptosis, what is the role of the Fas receptor?

Accepted Answer

It recruits adaptor proteins to form the death-inducing signaling complex (DISC), leading to caspase-8 activation

Question 7

What is the significance of cytochrome c release from mitochondria in the intrinsic pathway of apoptosis?

Accepted Answer

It binds Apaf-1, leading to apoptosome formation and activation of initiator caspase-9

Question 8

Which of the following best describes the function of Bcl2 family proteins in apoptosis?

Accepted Answer

They regulate mitochondrial outer membrane permeabilization, controlling the release of cytochrome c.

Question 9

A mutation that causes overexpression of XIAP (X-linked inhibitor of apoptosis protein) would most likely result in which of the following cellular outcomes?

Accepted Answer

Inhibition of caspase activity and resistance to apoptosis

Question 10

Which of the following scenarios best illustrates the importance of apoptosis in maintaining tissue homeostasis?

Accepted Answer

Programmed cell death of immune cells after an infection has been cleared

Question 11

A patient is found to have a mutation in the gene encoding Apaf-1, rendering it nonfunctional. Which step in the intrinsic apoptotic pathway would be directly affected?

Accepted Answer

Formation of the apoptosome and activation of caspase-9

Question 12

Which equation best represents the dimerization and activation of initiator caspases in the apoptotic pathway?

Accepted Answer

$$2 	imes 	ext{procaspase monomer} ightarrow 	ext{initiator caspase dimer}$$

Question 13

A researcher treats cells with a drug that blocks the activity of executioner caspases. Which of the following would most likely be observed?

Accepted Answer

Accumulation of uncleaved cellular proteins and lack of typical apoptotic morphology

Question 14

Which of the following is a direct consequence of mitochondrial outer membrane permeabilization (MOMP) during apoptosis?

Accepted Answer

Release of cytochrome c into the cytosol

Question 15

In a scenario where a cell expresses a mutant Bcl2 protein that cannot bind Bax or Bak, what is the most likely outcome?

Accepted Answer

Increased mitochondrial outer membrane permeabilization and enhanced apoptosis

Question 16

Which of the following best explains why apoptosis is considered a 'clean' form of cell death compared to necrosis?

Accepted Answer

Apoptotic cells are rapidly engulfed and digested by phagocytes, preventing inflammation.

Question 17

A scientist observes that after UV treatment, cells show diffuse cytochrome c-GFP signal in the cytosol rather than being localized to mitochondria. What does this indicate?

Accepted Answer

Cytochrome c has been released from mitochondria, indicating activation of the intrinsic apoptotic pathway.

Question 18

Which of the following is a multi-step process that integrates both extrinsic and intrinsic apoptotic pathways?

Accepted Answer

Activation of caspase-8 by Fas receptor, which then cleaves Bid to activate mitochondrial cytochrome c release

Question 19

Which of the following best describes the role of Smac/DIABLO and Omi in apoptosis?

Accepted Answer

They antagonize IAPs (inhibitor of apoptosis proteins) like XIAP, promoting caspase activation.

Chapter 18: Cell Death – Apoptosis and Necrosis

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