Apoptosis: Programmed Cell Death
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Questions and Answers

What is the role of ced-3 and ced-4 genes in cell death?

  • They are involved in cell growth
  • They are required for cell death (correct)
  • They are involved in cell division
  • They inhibit cell death

    • What is the function of CED-3 protein?

  • It cleaves after aspartate residues (correct)
  • It cleaves after alanine residues
  • It cleaves after serine residues
  • It cleaves after glutamate residues

    • What is the name of the mammalian homologue of CED-3 identified in 1993?

  • Caspase-1 alpha
  • Apaf-1 (apoptotic protease activating factor)
  • ICE (interleukin-1L converting enzyme) (correct)
  • Caspase-9

    • What is the function of CED-4 protein?

    <p>It interacts with both CED-3 and CED-9 proteins</p> Signup and view all the answers

    What is the role of ced-9 gene in cell death?

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

    What is the name of the mammalian homologue of CED-4?

    <p>Apaf-1 (apoptotic protease activating factor)</p> Signup and view all the answers

    What is the characteristic of apoptotic cells?

    <p>They are shrunken and develop blebs</p> Signup and view all the answers

    What is the role of Apaf-1 in regulating caspase activity?

    <p>It mediates cytochrome c-dependent activation of caspase-9</p> Signup and view all the answers

    What is the function of tumour suppressor p53?

    <p>Transcriptional activator of the human bax gene.</p> Signup and view all the answers

    What is the role of apoptosis in pathology?

    <p>Apoptosis is a mechanism in pathology.</p> Signup and view all the answers

    What is the function of Nedd2 (caspase-2) precursor?

    <p>Dimerization and autoprocessing requires both the prodomain and the carboxyl-terminal regions.</p> Signup and view all the answers

    What is the role of apoptosis in kidney development?

    <p>Apoptosis is involved in the coordination of early kidney development.</p> Signup and view all the answers

    What is the role of antioxidant supplements?

    <p>Antioxidant supplements are used to prevent gastrointestinal cancers.</p> Signup and view all the answers

    What is the role of phagocytosis in apoptosis?

    <p>Phagocytosis is involved in the recognition of cells undergoing apoptosis.</p> Signup and view all the answers

    What is the role of p53 in apoptosis?

    <p>p53 induces apoptosis.</p> Signup and view all the answers

    What is the role of apoptosis in shaping developing tissues?

    <p>Apoptosis is involved in shaping developing tissues.</p> Signup and view all the answers

    What is the primary role of apoptosis in development?

    <p>Eliminating specific populations of cells at different stages of embryogenesis</p> Signup and view all the answers

    Which of the following is a consequence of a critical failure of apoptosis?

    <p>Survival of cells after mutagenic DNA damage</p> Signup and view all the answers

    What is the role of apoptosis in the immune system?

    <p>Negative selection of T-cells</p> Signup and view all the answers

    What is the consequence of dysregulated apoptosis in the gastrointestinal tract?

    <p>Increased risk of liver cancer</p> Signup and view all the answers

    What is the primary source of reactive oxygen species (ROS)?

    <p>Normal cellular metabolism</p> Signup and view all the answers

    What is the role of apoptosis in cancer therapy?

    <p>Initiating apoptosis in cancer cells</p> Signup and view all the answers

    What is the consequence of oxidative stress in carcinogenesis?

    <p>Increased risk of cancer</p> Signup and view all the answers

    What is the role of apoptosis in maintaining the normal gut epithelial function?

    <p>Essential for maintaining the normal gut epithelial function</p> Signup and view all the answers

    What is the potential role of antioxidants in preventing the development of cancer?

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

    What is the term used to describe the process of cell death that is associated with diseases?

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

    Which of the following is a type of cell death that is not regulated by the cell?

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

    What is the main function of apoptosis?

    <p>To eliminate unnecessary or damaged cells</p> Signup and view all the answers

    What is the name of the nematode worm that has been used to study programmed cell death?

    <p>Caenorhabditis elegans</p> Signup and view all the answers

    Which of the following is a mechanism of cell death in hypoxia/reoxygenation injury?

    <p>Endonuclease activation</p> Signup and view all the answers

    What is the name of the receptors that initiate apoptosis?

    <p>Both A and B</p> Signup and view all the answers

    What is the term used to describe the process of cell death that is induced by glucocorticoids in thymocytes?

    <p>Glucocorticoid-induced thymocyte apoptosis</p> Signup and view all the answers

    What is the characteristic of the cell membrane during apoptosis?

    <p>It bulges outward</p> Signup and view all the answers

    Which of the following is a regulator of apoptosis?

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

    What happens to the organelles during apoptosis?

    <p>They remain intact</p> Signup and view all the answers

    What is the purpose of the 'phase of decision' in apoptosis?

    <p>To trigger the execution phase</p> Signup and view all the answers

    What is the term used to describe the study of cell death?

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

    What is the final stage of apoptosis?

    <p>Phagocytosis and DNA degradation</p> Signup and view all the answers

    What can initiate apoptosis?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of apoptosis during development?

    <p>To eliminate unnecessary cells</p> Signup and view all the answers

    Study Notes

    Apoptosis: Programmed Cell Death

    • Apoptosis, or programmed cell death, is a physiological process in which an organism eliminates unnecessary or damaged cells.
    • It is a predominant form of physiological cell death and plays a crucial role in normal development and disease.
    • Apoptosis is characterized by cell membrane blebbing, cell shrinkage, nuclear fragmentation, and chromatin condensation.
    • Organelles are almost intact, and changes in cell surface molecules ensure that the apoptotic cell is immediately recognized and phagocytosed by neighboring cells without inducing inflammation.

    Cell Death in Caenorhabditis elegans

    • In Caenorhabditis elegans, protein products of three genes are involved in cell death: ced-3, ced-4, and ced-9.
    • Ced-3 and ced-4 are required for cell death, while ced-9 antagonizes their killing activity.
    • Ced-3 encodes a cysteine protease, a caspase, which cleaves after aspartate residues.

    Mammalian Homologues of CED-3 and CED-4

    • The first mammalian homologue of CED-3 was identified in 1993 as ICE (interleukin-1 beta converting enzyme), now called caspase-1.
    • A mammalian homologue of CED-4 has been identified as Apaf-1 (apoptotic protease activating factor), which interacts with both CED-3 and CED-9 proteins.

    Apoptosis in Development and Disease

    • Apoptosis plays a crucial role in sculpting the shape and organization of organs during development.
    • It is essential for maintaining normal gut epithelial function and is involved in various pathological conditions of the gastrointestinal tract, such as inflammatory bowel disease and liver cancer.
    • Apoptosis is also involved in negative selection in the immune system and in the elimination of cells after mutagenic DNA damage.

    Apoptosis and Oxidative Stress

    • Reactive oxygen species (ROS) generated by cells as by-products of normal metabolism can play a role in carcinogenesis.
    • Oxidative stress may stimulate the development of cancer, and dietary antioxidants may prevent cancer development.

    Regulation of Apoptosis

    • Apoptosis can be initiated by various physiological and pathological stimuli, which act through receptors, biochemical agents, or DNA damage and cell membrane disruption.
    • The death receptor system, including Fas receptors and TNF receptors, can initiate apoptosis.
    • Two signaling pathways, the intrinsic and extrinsic pathways, lead to apoptosis and can overlap.

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    Explore the process of apoptosis, a natural mechanism of eliminating damaged cells, crucial for normal development and disease prevention.

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