Cellular Biology I - Cell Death Mechanisms
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What is a characteristic feature of autophagic cell death?

  • Condensation of chromatin
  • Presence of phagocytes engulfing the cells
  • Formation of necrotic tissue
  • Massive autophagic vacuolization of the cytoplasm (correct)

    • What process marks the completion of the autophagic pathway?

  • Release of cytosolic Ca2+
  • Separation of daughter nuclei during mitosis
  • Degradation of autophagosome content by lysosomes (correct)
  • Formation of protein aggregates

    • Which cell death modality is specifically induced by the loss of attachment to the substrate?

  • Mitotic catastrophe
  • Corneification
  • Excitotoxicity
  • Anoikis (correct)

    • What happens during excitotoxicity in neurons?

    <p>There is an opening of Ca2+-permeable channels</p> Signup and view all the answers

    Which of the following describes mitotic catastrophe?

    <p>Cell death characterized by multinucleation during failed mitosis</p> Signup and view all the answers

    What is the main characteristic that distinguishes apoptosis from necrosis?

    <p>Apoptosis is orderly and highly regulated.</p> Signup and view all the answers

    What triggers necrosis as opposed to apoptosis?

    <p>Direct damage to the cell.</p> Signup and view all the answers

    Which of the following best describes programmed cell death?

    <p>A cleanly executed cellular death mechanism.</p> Signup and view all the answers

    What does the Nomenclature Committee on Cell Death (NCCD) aim to clarify?

    <p>The morphological and biochemical interpretations of cell death.</p> Signup and view all the answers

    Which of the following options is a feature of apoptotic cell death?

    <p>Induced by physiological signals.</p> Signup and view all the answers

    How can cell death be categorized based on its triggering mechanisms?

    <p>Based on signal dependency and specific triggers.</p> Signup and view all the answers

    Which cellular process is likely to lead to permanent plasma membrane permeabilization?

    <p>Necrosis.</p> Signup and view all the answers

    Which of the following is NOT a common cause of necrosis?

    <p>Predetermined genetic signals.</p> Signup and view all the answers

    What is the defining characteristic of a cell undergoing apoptosis?

    <p>fragmentation into apoptotic bodies</p> Signup and view all the answers

    Which of the following processes indicates irreversible cell death?

    <p>massive activation of caspases</p> Signup and view all the answers

    What is the role of caspases in apoptosis?

    <p>to cleave specific proteins leading to cell disassembly</p> Signup and view all the answers

    Which pathway is initiated when a cell senses stress and kills itself?

    <p>intrinsic pathway</p> Signup and view all the answers

    What morphological change is associated with a dead cell?

    <p>complete fragmentation of the nucleus</p> Signup and view all the answers

    What initiates the clearance of apoptotic cells by neighboring cells?

    <p>exposure of phosphatidylserine residues</p> Signup and view all the answers

    Which of the following is NOT classified as a type of cell death mentioned?

    <p>necrotic cell death</p> Signup and view all the answers

    What is a characteristic feature of cells undergoing immunogenic cell death?

    <p>activation of immune pathways</p> Signup and view all the answers

    How does the extrinsic pathway of apoptosis differ from the intrinsic pathway?

    <p>It is triggered by signals from other cells.</p> Signup and view all the answers

    Which alteration signifies that a cell has crossed the point-of-no-return?

    <p>permeabilization of the mitochondrial outer membrane</p> Signup and view all the answers

    Which initiator caspase activates downstream effector caspases in the intrinsic pathway?

    <p>Caspase-9</p> Signup and view all the answers

    What role does cytochrome c play in apoptosis?

    <p>It forms the apoptosome with APAF1.</p> Signup and view all the answers

    Which of the following correctly describes initiator caspases?

    <p>They are activated through dimerization and cleavage.</p> Signup and view all the answers

    Which pro-apoptotic signal is NOT mentioned as an inducer in the content?

    <p>Interferon</p> Signup and view all the answers

    What initiates the extrinsic pathway of apoptosis?

    <p>Interaction of surface receptors with their ligands</p> Signup and view all the answers

    Which of these is a role of effector caspases?

    <p>Cleaving target proteins post-activation</p> Signup and view all the answers

    What is the result of membrane contraction during apoptosis?

    <p>Formation of membrane introflexions</p> Signup and view all the answers

    Which initiator caspase is specifically associated with the extrinsic pathway?

    <p>Caspase-8</p> Signup and view all the answers

    What occurs to caspases during activation?

    <p>They dimerize and undergo proteolytic cleavage.</p> Signup and view all the answers

    Which statement accurately describes pro-caspases?

    <p>They must be cleaved to become active.</p> Signup and view all the answers

    What mediates the formation of membrane protrusions in cells?

    <p>Pannexin 1</p> Signup and view all the answers

    Which type of cell death leads to the fragmentation into apoptotic bodies?

    <p>Apoptosis</p> Signup and view all the answers

    What activates necroptosis?

    <p>Death receptor-ligand binding</p> Signup and view all the answers

    What happens during necrosis?

    <p>Cell contents are released due to membrane breakdown</p> Signup and view all the answers

    What is NOT a characteristic of necroptosis?

    <p>Progression dependent on caspase activity</p> Signup and view all the answers

    What type of signaling molecules do dying cells emit to attract phagocytes?

    <p>Find-me signals</p> Signup and view all the answers

    What is a feature of necroptosis compared to necrosis?

    <p>It progresses as a form of programmed necrosis</p> Signup and view all the answers

    Which consequence is associated with necrosis?

    <p>Inflammatory response</p> Signup and view all the answers

    What role do phagocytes play after cell death?

    <p>They eliminate the debris of dead cells</p> Signup and view all the answers

    Which organelle undergoes swelling during necrosis?

    <p>Mitochondria</p> Signup and view all the answers

    Study Notes

    Cellular Biology I - Cell Death Mechanisms

    • Cell Death: Irreversible degeneration of vital cellular functions, culminating in loss of integrity (permanent plasma membrane permeabilization or fragmentation) occurring as a decision to maintain tissue homeostasis.
    • Immunogenic Cell Death: A final decision by the cell to maintain tissue homeostasis, a process crucial for tissue maintenance.
    • Types of Cell Death:
      • Lysosomal Cell Death: A form of cell death involving lysosomal enzymes.
      • Apoptosis: Programmed cell death, an orderly and highly regulated process maintaining tissue homeostasis. Often characterized by DNA damage.
      • Pyroptosis: A form of programmed cell death involving inflammatory responses.
      • Necroptosis: Unregulated (non-programmed) cell death. Characterized by swelling of the cell, breakdown of the membrane, and inflammation.
      • Ferroptosis: A form of cell death caused by iron accumulation.
      • Oxeiptosis: Cell death mediated by oxidative stress
      • Parthanatos: A form of programmed necrosis resulting from DNA damage. -NETosis: A form of programmed cell death that involves the formation of neutrophil extracellular traps (NETs).
      • Autosis: Self-destructive cellular degradation of organelle components.
      • Entosis: One cell engulfing another cell.
      • Alkaliptosis: Cell death triggered by an increase in intracellular pH; characterized by cell membrane disruption.

    Morphological Criteria for Cell Death

    • Membrane Integrity: Loss of integrity in the plasma membrane; this is often assessed with vital dyes (e.g., PI).
    • Cellular Fragmentation: Breakdown of a cell into discrete bodies(apoptotic bodies).
    • Phagocytosis: Adjacent cells engulfing the corpse.

    Necrosis

    • Characteristics: Unprogrammed, overwhelming insult, extreme physical/chemical stress or osmotic shock.
    • Morphological changes: Swelling of cell and organelles, membrane breakdown, and leakage of contents.
    • Outcome: Inflammation is induced by cellular components and death.
    • Types of Necrosis:
      • Coagulative: Protein denaturation
      • Liquefactive: Degradation/breakdown to liquid
      • Caseous: Granular appearance

    Apoptosis - Intrinsic Pathway

    • Initiation: Occurs when a cell senses internal stress or damage involving mitochondria, DNA damage, endoplasmic reticulum stress , and hypoxia (low oxygen) inducing cell death.
    • Key Players:
      • Bcl-2 family members: Regulate mitochondrial outer membrane permeabilization (MOMP), including BAX, BAK, BID ,and p53.
      • Mitochondria: Release of cytochrome c
      • Apaf-1: Activates Procaspase-9.
      • Executioner caspases: (Caspases-3, 6, and 7) lead to cell disassembly.

    Apoptosis - Extrinsic Pathway

    • Initiation: External signals (e.g., death receptors, TNF, TRAIL) induce apoptosis involving extracellular triggers.
    • Key players:
      • Death receptors: (e.g., Fas, TNF Receptor, TRAIL receptors).
      • Adaptor proteins: FADD, TRADD
      • Initiator caspases: (e.g., Caspase-8) activating the cascade.
      • Executioner caspases: (e.g., Caspases-3, 6, and 7) lead to cell disassembly.

    Caspase Cascade

    • Caspases: Cysteine proteases that cleave specific proteins leading to cellular disassembly.
    • Initiator caspases: trigger the apoptosis cascade and activate downstream effectors.
    • Effectors: Activate downstream caspases and induce cell death.

    Other Cell Death Modalities

    • Necroptosis: A form of programmed necrosis, triggered by death receptors, foreign microbial nucleic acids.
    • Pyroptosis: Programmed cell death related to pathogen inflammation
    • Autophagic cell death: Elimination of damaged or unneeded cell components through lysosomal fusion.
    • Ferroptosis: Cell death involving iron accumulation/oxidative stress
    • Mitotic catastrophe: Excessive/abnormal cell division leading to cell death.
    • Anoikis: Programmed cell death that induces cell detachment
    • Excitotoxicity: Result of overstimulation causing excessive calcium influx
    • Corneification: Final stage of epidermal cell differentiation.

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    Cell Death Mechanisms 2024-25 PDF

    Description

    Explore the various mechanisms of cell death, including apoptosis, necroptosis, and ferroptosis, essential for maintaining tissue homeostasis. This quiz covers definitions, processes, and types of cell death crucial for cellular biology. Test your knowledge on how these cell death mechanisms impact tissue maintenance and responses to damage.

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