Sect 9 Quiz Mixed Hard
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Questions and Answers

Which of the following best describes stem cells?

  • Specialized cells that cannot divide
  • Cells that only exist in embryos
  • Undifferentiated cells capable of self-renewal and differentiation (correct)
  • Cells that have no defined function

    • Apoptosis is a form of programmed cell death that occurs when a cell is damaged.

    True

    What is meant by 'cell lineage'?

    The developmental history of a cell from its birth until its final differentiation into a specialized cell type.

    Which type of stem cells have the highest potential for differentiation?

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

    The process of a cell dividing into two identical cells is known as __________ cell division.

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

    Fetal stem cells are less powerful than adult stem cells.

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

    Which of the following cell types is NOT a category of stem cells?

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

    What stage do human embryos reach where each cell can form every tissue?

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

    Match the terms to their correct definitions:

    <p>Apoptosome = A protein complex responsible for activating caspases Caspases = Enzymes that execute the cell death program Embryonic stem cells = Cells that can become any cell type in the body Bcl-2 family = Proteins that regulate apoptosis</p> Signup and view all the answers

    Embryonic stem cells are derived from the __________ of an early-stage embryo.

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

    Multipotent stem cells can differentiate into any cell type in the body.

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

    Match the following types of stem cells with their characteristics:

    <p>Fetal stem cells = More powerful than adult stem cells Embryonic stem cells = Most potential for differentiation Adult stem cells = Multipotent and involved in cell replacement Induced stem cells = Reprogrammed adult cells</p> Signup and view all the answers

    What is a key characteristic of iPS cells?

    <p>Induced pluripotent stem cells can be generated from adult cells and can differentiate into any cell type.</p> Signup and view all the answers

    What term describes stem cells that can give rise to all embryonic tissues but not extraembryonic tissues?

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

    Adult stem cells can be grown indefinitely in culture.

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

    Which transcription factors are crucial for maintaining the pluripotency of embryonic stem cells?

    <p>Oct4, Sox2, and Nanog</p> Signup and view all the answers

    What is the primary characteristic of multipotent cells?

    <p>They can develop into multiple, but not all, cell types.</p> Signup and view all the answers

    Intestinal stem cells proliferate and generate all types of epithelial cells within the intestine.

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

    Where are stem cells located in the intestinal epithelium?

    <p>Deep in the intestinal wall in pits called crypts.</p> Signup and view all the answers

    Hematopoietic stem cells replenish all necessary _____ cells.

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

    Match the following terms with their descriptions:

    <p>Multipotent cells = Can develop into multiple cell types Pluripotent cells = Can develop into any cell type Transiently amplifying cells = Rapidly divide and produce restricted progenitor cells Niche = Specialized environment that supports stem cells</p> Signup and view all the answers

    What significantly controls the proliferation and differentiation of stem cells in niches?

    <p>Signaling pathways</p> Signup and view all the answers

    Intestinal epithelial cells are only regenerated when damaged.

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

    What is the turnover rate of intestinal epithelium cells in humans?

    <p>Every 5 days</p> Signup and view all the answers

    What is the primary role of enterocytes when the Notch signal is present?

    <p>To differentiate into absorptive enterocytes</p> Signup and view all the answers

    Paneth cells are produced every 3-6 weeks from Lgr5+ cells.

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

    What distinguishes tuft cells from other intestinal cells?

    <p>They are chemosensory cells.</p> Signup and view all the answers

    The main function of goblet cells is to secrete ________.

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

    Which factor is NOT involved in deriving induced pluripotent stem (iPS) cells?

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

    Match the following cell types with their functions:

    <p>Goblet cells = Secrete mucus M cells = Take up intestinal antigens Paneth cells = Secrete antimicrobial proteins iPS cells = Can differentiate into various cell types</p> Signup and view all the answers

    What type of cell division do many yeasts and fungi undergo?

    <p>Symmetric cell division</p> Signup and view all the answers

    Telocytes are the primary source of growth factors necessary for stem cell self-renewal.

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

    What is a requirement for asymmetric cell division to occur?

    <p>The parental cell must become polarized before division.</p> Signup and view all the answers

    All daughter cells produced by asymmetric cell division are identical in size and shape.

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

    What are the three components of the conserved apoptotic pathways in vertebrate cells?

    <p>Membrane-bound regulatory proteins, cytosolic regulatory proteins, apoptotic proteases.</p> Signup and view all the answers

    Without trophic factors, vertebrate cells undergo __________.

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

    Match the following terms with their descriptions:

    <p>Caspases = Apoptotic proteases in vertebrates Cell polarity determinants = Asymmetrically localized mRNAs, proteins, and lipids Signal transduction pathway = Initiates the regulation of the cytoskeleton Apoptosis = Programmed cell death</p> Signup and view all the answers

    What is the first step in generating polarized cells?

    <p>Exposing cells to a spatial clue.</p> Signup and view all the answers

    The mitotic spindle's position can affect the fate of the daughter cells.

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

    Asymmetric cell division involves the unequal distribution of cell contents, such as __________ and proteins.

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

    What is the primary function of caspases once activated?

    <p>Cleavage of specific intracellular substrates</p> Signup and view all the answers

    Caspase activation can occur without the binding of CED-4 and Apaf-1.

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

    What happens to apoptotic cells during the process of apoptosis?

    <p>They shrink, condense, and fragment into membrane-bound apoptotic bodies.</p> Signup and view all the answers

    Bcl-2 family proteins include both pro- and anti-______ proteins.

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

    Which proteins promote caspase activation and cell death by escaping into the cytosol?

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

    The Bcl-2 protein facilitates apoptosis by preventing the oligomerization of Bax and Bak.

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

    What triggers the oligomerization of Bax and Bak proteins?

    <p>Environmental stress or activation of BH3-only proteins.</p> Signup and view all the answers

    Match each protein to its role in apoptosis:

    <p>Bax = Pro-apoptotic protein that forms channels in the mitochondrial membrane Bcl-2 = Anti-apoptotic protein that inhibits Bax and Bak Puma = BH3-only protein that promotes apoptosis 14-3-3 protein = Sequesters phosphorylated Bad</p> Signup and view all the answers

    Study Notes

    Stem Cells, Cell Asymmetry, and Cell Death

    • Learning Objectives: Define apoptosis, apoptosome, asymmetric/symmetric cell division, Bcl-2 family, caspases, cell fate, cell lineage, embryonic stem cells, iPS cells, multipotent, pluripotent, progenitor cells, stem cell, stem-cell niche survival signals, and totipotent. Differentiate stem cell categories. Discuss key stem cells in the intestinal stem cell niche. Compare apoptosis and necrosis.

    • Cell Lineage: Developmental history of a cell from birth to final division and differentiation is its cell fate. Cell lineage traces the birth order of cells as they progressively become more specific in development. Examples include the nematode worm C. elegans.

    • Stem Cells: Unspecialized cells capable of self-renewal and generating specialized cells. Four main types: adult stem cells (derived from adult tissues), fetal stem cells (from fetuses), embryonic stem cells (from blastocysts), and induced pluripotent stem cells (iPS) (adult cells reprogrammed).

    • Totipotent Cells: Human embryos at the 8-cell stage, each still capable of forming all embryonic and extraembryonic tissues (e.g., placental).

    • ES Cells: At the blastocyst stage, a distinctive inner cell mass can form embryonic stem cells (ES cells) that have the potential to generate all embryonic tissues, but not extraembryonic tissues. ES cells are pluripotent.

    • Pluripotency of ES Cells: Controlled by factors like DNA methylation, chromatin regulators, microRNAs, and transcription factors (Oct4, Sox2, Nanog).

    • Adult Stem Cells: Multipotent, capable of differentiating into various cell types within a specific tissue, but less versatile than ES cells. Important for tissue maintenance and repair.

    • Polarized Cells: Cells that develop a distinct orientation. Cells use receptors to sense cues, initiate signal transduction pathways, and reorganize their cytoskeleton.

    • Cell Polarity Determinants: MRNAs, proteins, and lipids organized in a non-uniform, localized way within the cell. This organization leads to different fate determinants in daughter cells during the cell division.

    • Cell Death (Apoptosis): Programmed cell death in vertebrates, with three components: membrane-bound regulatory proteins, cytosolic regulatory proteins, and apoptotic proteases (caspases).

    • Apoptotic Pathways: Activated caspases cleave specific intracellular substrates leading to cell demise. Other proteins (CED-4 and Apaf-1) are essential for caspase activation. Apoptotic cells shrink, condense, and fragment. They are engulfed, versus necrotic cells.

    • Bcl-2 Family Proteins: Transmembrane proteins containing pro- and anti-apoptotic members. Pro-apoptotic Bcl-2 family members (Bax and Bak) form channels in the mitochondrial membrane leading to cell death, while anti-apoptotic members (Bcl-2, Bcl-XL) prevent oligomerization of Bax/Bak and cell death.

    • Fas-mediated Apoptosis: Binding of extracellular death signals (e.g., TNFα and Fas Ligand) to their respective receptors triggers the caspase cascade.

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    Description

    Test your understanding of stem cells, including their types, functions, and roles in development. Explore concepts like apoptosis, cell asymmetry, and the significance of various stem cell niches. This quiz will help reinforce your knowledge of cellular processes.

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