Cellular Differentiation and Stem Cells
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Cellular Differentiation and Stem Cells

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Questions and Answers

What is the primary result of apoptosis in the interdigital tissue of a developing mouse embryo?

  • Elimination of tissue between digits (correct)
  • Regeneration of digits
  • Promotion of muscle development
  • Increased cell proliferation

    • Which pathway is activated by internal signals during apoptosis?

  • Extrinsic pathway
  • Secondary pathway
  • Receptor-mediated pathway
  • Intrinsic pathway (correct)

    • What role does thyroid hormone play during the metamorphosis of a tadpole into a frog?

  • Stimulates tail regeneration
  • Enhances growth of limbs
  • Induces apoptosis in tail cells (correct)
  • Increases feeding behavior

    • What initiates the extrinsic apoptosis pathway?

    <p>External signals from other cells</p> Signup and view all the answers

    What is released by Bax and Bak to activate the apoptosome in the intrinsic pathway?

    <p>Cytochrome c</p> Signup and view all the answers

    Which of the following statements about apoptosis is true?

    <p>It can regulate cell numbers and eliminate damaged cells.</p> Signup and view all the answers

    What is the consequence of mitochondrial DNA damage?

    <p>Mitochondrial dysfunction</p> Signup and view all the answers

    Which caspase is activated by the apoptosome during apoptosis?

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

    What is the main role of transcription factors in gene expression?

    <p>To bind to specific genes and regulate their transcription</p> Signup and view all the answers

    Which type of stem cells can give rise to any of the 220 cell types found in an embryo?

    <p>Totipotent stem cells</p> Signup and view all the answers

    How do pluripotent stem cells differ from totipotent stem cells?

    <p>Pluripotent stem cells can give rise to all cell types of the body but not placenta</p> Signup and view all the answers

    Which of the following statements about cell potency is true?

    <p>Cell potency is the ability of stem cells to differentiate into specialized cell types</p> Signup and view all the answers

    What occurs as a result of the action of transcription factors in a cell?

    <p>Cells specialize into specific types based on gene expression</p> Signup and view all the answers

    Which type of stem cells has the capacity to develop into a limited subset of cell types?

    <p>Multipotent stem cells</p> Signup and view all the answers

    What is the primary characteristic of stem cells that distinguishes them from other cell types?

    <p>They can divide and renew themselves for extended periods.</p> Signup and view all the answers

    What function do transcription factors serve in relation to RNA polymerase?

    <p>They regulate the binding of RNA polymerase to genes on DNA</p> Signup and view all the answers

    In what way do all body cells share a common feature despite their differentiation?

    <p>They contain the entire genome of the organism</p> Signup and view all the answers

    Which of the following best describes the process of cellular differentiation?

    <p>Cells undergo changes to become more specialized for specific functions.</p> Signup and view all the answers

    Which type of cell is primarily responsible for secreting mucus in the gastrointestinal tract?

    <p>Goblet cells</p> Signup and view all the answers

    What role do transcription factors play in stem cell differentiation?

    <p>They regulate the genes that influence the differentiation pathway.</p> Signup and view all the answers

    What distinguishes embryonic stem cells from adult stem cells?

    <p>Embryonic stem cells have a wider differentiation potential than adult stem cells.</p> Signup and view all the answers

    Cells that absorb nutrients in the gastrointestinal tract share a origin with which other type of specialized cell?

    <p>Goblet cell</p> Signup and view all the answers

    Which statement about stem cells is false?

    <p>They can only reproduce in very specific environments.</p> Signup and view all the answers

    What is a major change that occurs in a cell during differentiation?

    <p>Cells may change shape and metabolic activity.</p> Signup and view all the answers

    What is the primary function of endonuclease G during apoptosis?

    <p>To cause DNA fragmentation</p> Signup and view all the answers

    Which phase involves the recognition of apoptotic cells by macrophages?

    <p>Phagocytic phase</p> Signup and view all the answers

    What happens during the degradation phase of apoptosis?

    <p>Apoptotic bodies are formed</p> Signup and view all the answers

    What leads to the depolarization and swelling of mitochondria in apoptosis?

    <p>Permeability transition pore complex activity</p> Signup and view all the answers

    Which of the following accurately describes a morphological change occurring during apoptosis?

    <p>Chromatin condensation occurs</p> Signup and view all the answers

    Which enzymes are primarily activated during the degradation phase of apoptosis?

    <p>Effectors caspases 3, 6 and 7</p> Signup and view all the answers

    What is displayed on the outer cell membrane to signal phagocytosis during apoptosis?

    <p>Phosphatidyl serine</p> Signup and view all the answers

    What are the typical outcomes of mitochondrial dysfunction during the apoptotic process?

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

    Which type of cells can be induced to reenter the cell cycle by growth factors?

    <p>Stabile cells</p> Signup and view all the answers

    What is the primary distinction between pluripotent and totipotent stem cells?

    <p>Totipotent cells can differentiate into any cell needed for organism development, while pluripotent cells cannot support full development.</p> Signup and view all the answers

    Which of the following cells has lost all capacity for proliferation?

    <p>Cardiac muscle cells</p> Signup and view all the answers

    Which type of stem cell is limited to differentiating into a small number of cell types?

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

    What is the function of transcription factors in cellular differentiation?

    <p>To activate or repress gene expression affecting the cell's proteome.</p> Signup and view all the answers

    Modern biological theories of aging do NOT include which one of the following categories?

    <p>Genetic theories</p> Signup and view all the answers

    Which of the following statements is true regarding cellular aging based on programmed theories?

    <p>It proposes that aging follows a specific biological timetable.</p> Signup and view all the answers

    Which cells continuously divide and include surface epithelial cells of the skin?

    <p>Labile cells</p> Signup and view all the answers

    Study Notes

    Cellular Differentiation

    • Cells differentiate to become specialized, leading to changes in size, shape, function, and metabolic activity.
    • Tissues are organized communities of cells with specific functions.
    • The endothelial tissue lining the gastrointestinal tract contains cells with various roles like nutrient absorption and mucus secretion.

    Stem Cells

    • Stem cells differentiate into various cell types.
    • Stem cells can:
      • Self-renew over a long time
      • Are unspecialized
      • Become specialized cells like muscle, blood, and brain cells

    Stem Cell Potency

    • Stem cell potency refers to their ability to differentiate.
    • Totipotent stem cells (omnipotent) can form any cell type in an embryo and extra-embryonic cells.
    • Pluripotent stem cells differentiate into any human cell type except extra-embryonic cells.
    • .Multipotent stem cells have limited differentiation potential, typically within a specific lineage.

    Transcription Factors in Differentiation

    • Transcription factors regulate gene expression by binding to DNA and promoting or hindering gene transcription.
    • They are responsible for the specialization of cells into various cell types.

    Proliferative Capability of Cells

    • Labile cells, like skin and gut epithelial cells, continuously divide.
    • Stable cells, like liver, kidney, and pancreatic cells, divide when exposed to growth factors.
    • Permanent cells, like nerve and cardiac muscle cells, do not typically divide.

    Cellular Aging

    • Aging theories include programmed and damage or error theories.
    • Programmed theory suggests aging follows a biological timetable, potentially regulated by gene expression changes affecting maintenance, repair, and defense mechanisms.
    • Damage or error theories posit that aging is caused by accumulating damage or errors in cells and tissues.

    Apoptosis

    • Apoptosis is a programmed cell death that can be induced by signals from other cells.
    • It plays a crucial role in development, such as the removal of interdigital tissue during limb development.
    • Apoptosis is also essential for regulating cell numbers and eliminating damaged cells.

    Apoptosis Pathways

    • Apoptosis is triggered by two primary pathways:
      • The intrinsic (mitochondrial) pathway: triggered by internal signals like cell stress or DNA damage.
      • The extrinsic (death receptor) pathway: activated by external signals from other cells.

    Key Events in the Intrinsic Pathway

    • Bax and Bak form pores in mitochondrial membranes, releasing cytochrome c.
    • Released cytochrome c activates procaspase 9, forming the apoptosome.
    • Activated caspase 9 triggers downstream caspases, leading to cell death.

    Key Events in Apoptosis

    • The cellular cortex (actin microfilaments) and the nucleus are disassembled by caspases.
    • Endonuclease G fragments DNA.
    • Apoptosis Inducing Factor (AIF) condenses chromatin and fragments DNA.
    • The permeability transition pore complex in mitochondrial membranes leads to depolarization, uncoupling of oxidative phosphorylation, swelling, ATP depletion, and ultimately cell death.

    Stages of Apoptosis

    • Activation phase: signal reception and activation of caspases.
    • Execution phase: mitochondrial release of pro-apoptotic factors executioner caspases activation, and dismantlement of the cell.
    • Degradation phase: cell dismantling, DNA fragmentation, and formation of apoptotic bodies.
    • Phagocytic phase: removal of apoptotic bodies by macrophages without inflammation.

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    Life Sciences I - Cell Biology - Apoptosis - PDF

    Description

    Explore the fascinating processes of cellular differentiation and the role of stem cells in development. This quiz covers key concepts like stem cell potency and the impact of transcription factors. Test your understanding of how cells specialize and form tissues in the body.

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