Lecture 20
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Questions and Answers

What is the correct order of organization in multicellular organisms?

  • Tissues → Organs → Organ Systems → Body → Cells
  • Body → Organ Systems → Organs → Tissues → Cells
  • Cells → Tissues → Organs → Organ Systems → Body (correct)
  • Organs → Tissues → Cells → Body

    • What is the main component of animal connective tissues?

  • Extracellular matrix (correct)
  • Collagen fibrils
  • Osteocytes
  • Cells

    • What is the main function of collagen in animal connective tissues?

  • Providing tensile strength (correct)
  • Providing cushioning
  • Providing flexibility
  • Providing structural support

    • What type of modification occurs to collagen during its synthesis?

    <p>Glycosylation and acetylation</p> Signup and view all the answers

    What is the precursor to collagen?

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

    Why doesn't procollagen proteinase cleave procollagen inside the fibroblast?

    <p>Because the unstructured ends of procollagen prevent proteinase activity</p> Signup and view all the answers

    What happens to epithelial cells when apical bundles of actin filaments contract?

    <p>They narrow at their apex</p> Signup and view all the answers

    What is the fate of a vesicle in a developing animal?

    <p>Its fate depends on the orientation of contraction of the epithelial sheet</p> Signup and view all the answers

    What type of proteins binds to the dense plaque of intracellular linker proteins on the cytoplasmic side of the plasma membrane?

    <p>Cadherin proteins</p> Signup and view all the answers

    What is the function of hemidesmosomes in an epithelial cell?

    <p>To anchor the intermediate filaments to the basal lamina</p> Signup and view all the answers

    Why are integrins used in hemidesmosomes instead of cadherins?

    <p>Because integrins are specific to the basal lamina</p> Signup and view all the answers

    What is the earliest tube that forms in a developing embryo?

    <p>Neural tube</p> Signup and view all the answers

    How do integrins inform the cell that it is anchored to the extracellular matrix?

    <p>By undergoing a conformational change</p> Signup and view all the answers

    What triggers the switch to an active conformation in integrins?

    <p>Binding to fibronectin or intracellular adaptor proteins</p> Signup and view all the answers

    What do polysaccharides and proteins in tissues do, according to the text?

    <p>Fill spaces and resist compression</p> Signup and view all the answers

    What is the role of glycosaminoglycans (GAGs) in tissues?

    <p>Fulfilling the role of resisting compression</p> Signup and view all the answers

    What characterizes Hyaluronan as a glycosaminoglycan?

    <p>Consists of a single long chain with up to 25,000 repeated disaccharide units</p> Signup and view all the answers

    Why are the negative charges on glycosaminoglycans (GAGs) important to their function?

    <p>Affect the interaction with other extracellular matrix components</p> Signup and view all the answers

    What is a characteristic of oncogenes?

    <p>They act in a dominant manner.</p> Signup and view all the answers

    What happens to the function of tumor suppressor genes in cancer cells?

    <p>It is lost.</p> Signup and view all the answers

    What is a common feature of the key regulatory pathways perturbed in human cancers?

    <p>They regulate cell growth and proliferation.</p> Signup and view all the answers

    What type of mutations can convert a proto-oncogene into an oncogene?

    <p>Gain-of-function mutations.</p> Signup and view all the answers

    What is a characteristic of tumor suppressor genes?

    <p>They generally act in a recessive manner.</p> Signup and view all the answers

    What is the result of a loss-of-function mutation in a tumor suppressor gene?

    <p>The function of the gene is lost.</p> Signup and view all the answers

    What do gap junctions provide neighboring cells with?

    <p>Direct channel of intercytosolic communication</p> Signup and view all the answers

    Which protein assemblies penetrate the apposed membranes of adjacent cells in gap junctions?

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

    What do stem cells have the ability to do in terms of lineage production?

    <p>Renew themselves and produce terminally differentiated lineages</p> Signup and view all the answers

    Where does renewal occur continuously in the mammalian intestine?

    <p>In the epithelial lining</p> Signup and view all the answers

    What type of cells are primarily renewed from stem cells in the epidermis?

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

    Which type of stem cells are found in red bone marrow and give rise to various blood cell types?

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

    What maintains the proliferation of stem cells in the precursor cells of the intestinal crypts?

    <p>Wnt signaling pathway</p> Signup and view all the answers

    What protein interacts with the GPCR frizzled in the Wnt signaling pathway?

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

    Which cell types increase in production during an infection due to hemopoietic stem cells?

    <p>White blood cells (leukocytes)</p> Signup and view all the answers

    What allows stem cells of different types to be maintained in culture?

    <p>Culturing techniques</p> Signup and view all the answers

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