Extracellular Matrix Overview
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Questions and Answers

What is the primary structural composition of Chondroitin sulfate?

  • D-Glucoronic acid + D-galactose
  • D-Glucoronic acid + Galactosamine (correct)
  • L-iduronic acid + Galactosamine
  • D-Glucuronic acid + Glucosamine

    • Which GAG does NOT contain uronic acid?

  • Keratan sulfate (correct)
  • Chondroitin sulfate
  • Heparin
  • Dermatan sulfate

    • Which of the following GAGs is primarily responsible for maintaining corneal transparency?

  • Chondroitin sulfate
  • Dermatan sulfate
  • Hyaluronic acid
  • Keratan sulfate I (correct)

    • What is a key function of Heparin in the body?

    <p>Serving as an anticoagulant</p> Signup and view all the answers

    Which GAG aggregates primarily in cartilage and plays a role in its compressibility?

    <p>Chondroitin sulfate</p> Signup and view all the answers

    Which GAG can be degraded by an enzyme known as hyaluronidase?

    <p>Hyaluronic acid</p> Signup and view all the answers

    Where is Heparan sulfate predominantly found?

    <p>As a ubiquitous component of cell surface</p> Signup and view all the answers

    Which of the following is NOT a known function of hyaluronic acid?

    <p>Regulation of osmotic pressure in blood vessels</p> Signup and view all the answers

    Which GAG has multiple sulfate groups and is known for its role as an anticoagulant?

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

    In which type of connective tissue is Keratan sulfate II predominantly found?

    <p>Loose connective tissues</p> Signup and view all the answers

    What is one of the main functions of glycosaminoglycans in connective tissues?

    <p>To act as a natural lubricant in the joints</p> Signup and view all the answers

    Which glycosaminoglycan is specifically known for binding large amounts of water?

    <p>Chondroitin sulfates</p> Signup and view all the answers

    What outcomes are associated with hereditary enzyme deficiencies related to glycosaminoglycans?

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

    Which of the following symptoms is NOT typically associated with mucopolysaccharidosis?

    <p>Severe muscle hypertrophy</p> Signup and view all the answers

    What structural feature do glycosaminoglycans possess that contributes to their function?

    <p>Repeating disaccharide units</p> Signup and view all the answers

    What is the primary function of the hyaluronidase enzyme present in semen?

    <p>To degrade the gel surrounding the ovum</p> Signup and view all the answers

    Which of the following characteristics is unique to hyaluronic acid compared to other glycosaminoglycans (GAGS)?

    <p>Non-sulfated</p> Signup and view all the answers

    What type of genetic inheritance is primarily associated with mucopolysaccharidoses (MPS)?

    <p>Autosomal recessive</p> Signup and view all the answers

    What enzyme deficiency is responsible for Hurler's syndrome?

    <p>Alpha-L-iduronidase</p> Signup and view all the answers

    Which of the following features is NOT associated with dysotosis multiplex?

    <p>Increased height</p> Signup and view all the answers

    What distinguishes Hunter's syndrome from Hurler's syndrome?

    <p>It is due to a deficiency of iduronate sulfatase</p> Signup and view all the answers

    What is a common consequence of the accumulation of glycosaminoglycans in mucopolysaccharidoses?

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

    What enzyme deficiency is implicated in the structural abnormalities and mental retardation observed in the 5-year-old boy?

    <p>Alpha-L-iduronidase</p> Signup and view all the answers

    How does Sanfilipo's syndrome primarily manifest in affected individuals?

    <p>Mental retardation with mild structural features</p> Signup and view all the answers

    Which of the following is not a known feature of mucopolysaccharidoses?

    <p>Hyperactive behavior</p> Signup and view all the answers

    Which class of biomolecules primarily provides structural support in the extracellular matrix (ECM)?

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

    What is a significant consequence of GAGS accumulation in mucopolysaccharidoses?

    <p>Skeletal deformities and mental retardation</p> Signup and view all the answers

    What type of sugar forms the repeating disaccharide units in glycosaminoglycans (GAGs)?

    <p>Amino sugars and uronic acids</p> Signup and view all the answers

    What is one major function of glycosaminoglycans in the extracellular matrix?

    <p>Water binding and producing a gel-like matrix</p> Signup and view all the answers

    Which of the following is NOT a component of the extracellular matrix?

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

    Which of the following statements correctly describes glycosaminoglycans?

    <p>They consist of large complexes of negatively charged carbohydrates.</p> Signup and view all the answers

    What type of cells secrete the extracellular matrix components?

    <p>Connective tissue cells</p> Signup and view all the answers

    Which glycosaminoglycan is primarily associated with forming proteoglycans?

    <p>Chondroitin sulfate</p> Signup and view all the answers

    What is the enzyme defect responsible for Hurler's Syndrome?

    <p>a-L-iduronidase</p> Signup and view all the answers

    Which mucopolysaccharidosis is associated with the accumulation of keratan sulfate?

    <p>Morquio's Syndrome</p> Signup and view all the answers

    What symptom is not typically associated with MPS I (Hurler Syndrome)?

    <p>Severe skeletal deformities</p> Signup and view all the answers

    Which of the following mucopolysaccharidoses is X-linked?

    <p>MPS II</p> Signup and view all the answers

    The lack of which enzyme is responsible for Sanfilippo's Syndrome?

    <p>One of four degradative enzymes</p> Signup and view all the answers

    Which of the following statements regarding Mucopolysaccharidosis III (Sanfilippo Syndrome) is correct?

    <p>It primarily results in mental retardation with little structural change.</p> Signup and view all the answers

    What type of structural changes are common in MPS I (Hurler Syndrome)?

    <p>Unusual facial features and skeletal abnormalities</p> Signup and view all the answers

    Which mucopolysaccharidosis results from a defect in N-acetylglucosamine-4-sulfatase?

    <p>Maroteaux-Lamy's Syndrome</p> Signup and view all the answers

    How does heparan sulfate affect tumor cell behavior?

    <p>It reduces adhesiveness of tumor cells on their surface.</p> Signup and view all the answers

    What is the primary consequence of GAG accumulation in mucopolysaccharidosis?

    <p>Mental retardation and skeletal deformities</p> Signup and view all the answers

    Study Notes

    Extracellular Matrix (ECM)

    • ECM is a collection of extracellular molecules secreted by cells.
    • It provides structural and biochemical support to surrounding cells.
    • Composition of ECM varies between multicellular structures.
    • Functions include cell adhesion and cell-to-cell communication.

    Glycosaminoglycans (GAGs)

    • GAGs are large complexes of negatively charged heteropolysaccharide chains.
    • They have a special ability to bind large amounts of water.
    • GAGs produce a gel-like matrix, forming the basis of the body's ground substance surrounding cells.

    Composition of ECM

    • ECM is composed of structural proteins, specialized proteins, and proteoglycans.
    • Structural proteins include collagen and elastin.
    • Specialized proteins include fibrillin, fibronectin, and laminin.
    • Proteoglycans are a compound of protein bonded to a mucopolysaccharide group.

    Functions of ECM

    • Binding and packing of tissues (connective tissue proper)
    • Connecting, anchoring, and supporting the body and organs.
    • Transport of metabolites between capillaries and tissues.
    • Essential for processes like growth, wound healing, and fibrosis.
    • Defense against infection.
    • Repair of injury via cell proliferation and fiber formation.
    • Fat storage (linked to age, sex, nutrition, and disease).
    • Role in development, inflammatory states, and cancer cell spread.

    Functions of GAGs

    • Major component of the extracellular matrix.
    • Form a gel-like matrix, acting as a cushion.
    • Attract water and increase viscosity.
    • Lubricate joints.
    • Provide flexibility and elasticity to cartilage.

    Classification of GAGs

    • GAGs are classified as sulfate-free (e.g., hyaluronic acid) and sulfate-containing (e.g., chondroitin sulfate, keratan sulfate, heparin, and heparan sulfate, dermatan sulfate).

    Specific GAG examples

    • Hyaluronic acid: Sulfate-free, important component of synovial fluid, vitreous humor, and connective tissues.
    • Chondroitin sulfate: Found in cartilage.
    • Keratan sulfate: Found in the cornea and loose connective tissues.
    • Heparin: Intracellular, functions as an anticoagulant and lipoprotein lipase activator.
    • Heparan sulfate: A component of basement membranes and cell surfaces.
    • Dermatan sulfate: Found in skin, cardiac valves, and blood vessels.

    Mucopolysaccharidoses (MPS)

    • Rare inborn errors in the degradation of glycosaminoglycans
    • Hereditary disorders (usually autosomal recessive, except for MPSII which is X-linked)
    • Lysosomal hydrolases for GAGs are deficient.
    • GAGs accumulate, leading to symptoms such as skeletal and extracellular matrix deformities, and mental retardation.

    Examples of MPS diseases

    • Hurler syndrome (MPS I): Deficiency in α-L-iduronidase activity.
    • Hunter syndrome (MPS II): Deficiency in iduronate-2-sulfatase activity.
    • Sanfilippo syndrome (MPS III): Deficiency in one of the four enzymes needed to break down heparan sulfate.
    • Morquio syndrome (MPS IV): Deficiency in galactosamine-6-sulfatase, or N-acetylgalactosamine-6-sulfatase leads to accumulation of keratan sulfate.
    • Scheie syndrome (MPS I): milder form of Hurler syndrome.
    • Maroteaux-Lamy syndrome (MPS VI): Deficiency in N-acetylgalactosamine-6-sulfatase.
    • Sly syndrome (MPS VII): Deficiency in β-glucuronidase.

    Dysotosis Multiplex

    • Severe abnormalities in the development of cartilage and bone (chondrodystrophic skeletal changes)
    • Deposition of a lipid-like substance in various tissues.

    Association of GAGs with Cancer

    • Increased production of hyaluronic acid frequently observed in tumor cells.
    • Lower heparan sulfate levels associated with a lack of adhesiveness in some tumor cells.

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    Description

    This quiz offers an overview of the Extracellular Matrix (ECM), its composition, and its key functions in tissue support and cell communication. Additionally, it covers Glycosaminoglycans (GAGs) and their role in forming the matrix. Test your understanding of these crucial biological components.

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