Fibers and Hydroxy Amino Acids
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Questions and Answers

What substance is hydroxylated to form hydroxyproline and hydroxylysine?

  • Serine
  • Glycine
  • Lysine (correct)
  • Proline (correct)

    • Which type of fibers is the most abundant protein in the human body?

  • Reticular fibers
  • Elastic fibers
  • Collagen fibers (correct)
  • Myofibrils

    • Which of these is NOT one of the main types of fibers mentioned?

  • Elastic fibers
  • Collagen fibers
  • Reticular fibers
  • Neurofibers (correct)

    • What is the length of a tropocollagen unit?

    <p>280 nm</p> Signup and view all the answers

    Which of the following types of collagen is most commonly studied?

    <p>Type I collagen</p> Signup and view all the answers

    How many types of collagen have been described?

    <p>28</p> Signup and view all the answers

    What is the width of a tropocollagen unit?

    <p>1.5 nm</p> Signup and view all the answers

    What structural feature is unique to collagen fibers?

    <p>Triple helix formation</p> Signup and view all the answers

    What is the primary structural characteristic of fibrillar collagen types I, II, and III?

    <p>They have subunits that aggregate to form large fibrils clearly visible under microscopy.</p> Signup and view all the answers

    Which statement accurately describes collagen type I?

    <p>It is the most abundant collagen and forms large, eosinophilic bundles.</p> Signup and view all the answers

    What type of interactions are primarily responsible for the aggregation of tropocollagen molecules into fibrils?

    <p>Hydrogen and hydrophobic interactions.</p> Signup and view all the answers

    What is the periodicity of the transverse striations observed in collagen fibrils?

    <p>64 nm, determined by the overlapping arrangement of tropocollagen molecules.</p> Signup and view all the answers

    What role does lysyl oxidase play in collagen structure?

    <p>It catalyzes the covalent cross-linking of collagen fibrils.</p> Signup and view all the answers

    What is the primary function of plasma cells within connective tissue?

    <p>Synthesis of antibodies</p> Signup and view all the answers

    Which type of mast cell proteoglycan is found in connective tissue mast cells?

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

    What distinguishes mucosal mast cells from connective tissue mast cells?

    <p>Type of proteoglycan present</p> Signup and view all the answers

    How does adipose tissue contribute to body temperature regulation?

    <p>By storing neutral fats</p> Signup and view all the answers

    What cellular characteristic helps identify a typical plasma cell?

    <p>Compact coarse heterochromatin in the nucleus</p> Signup and view all the answers

    Which connective tissue is characterized as the most abundant and helps support epithelial tissue?

    <p>Areolar tissue</p> Signup and view all the answers

    What type of immune capability is associated with macrophages, mast cells, and plasma cells in connective tissue?

    <p>Defensive capabilities</p> Signup and view all the answers

    Which of the following properties does NOT describe mast cells?

    <p>Nucleus lacking a distinct shape</p> Signup and view all the answers

    What are the two primary components identified in the structure discussed?

    <p>Elastin and tubular microfibrils</p> Signup and view all the answers

    Which statement correctly describes the initial development of the components?

    <p>Microfibrils appear first, followed by elastin formation.</p> Signup and view all the answers

    What is the molecular weight of proelastin when secreted?

    <p>70,000</p> Signup and view all the answers

    Which of the following tissues is NOT primarily involved in elastin production?

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

    How does elastin differ in resistance compared to collagen fibers?

    <p>Elastin is more resistant to boiling and trypsin digestion.</p> Signup and view all the answers

    What type of interactions stabilize the tertiary and quaternary structure of elastin?

    <p>Hydrophobic interactions between nonpolar peptide chains</p> Signup and view all the answers

    Which characteristic of elastin contributes to its unique structural properties compared to collagen?

    <p>Elastin contains nonpolar peptide chains.</p> Signup and view all the answers

    Which feature primarily differentiates elastin from collagen fibers in terms of structural composition?

    <p>Elastin consists of amorphous regions rather than a defined structure.</p> Signup and view all the answers

    Which glycosaminoglycan is primarily associated with high levels of interaction with collagen type II?

    <p>Chondroitin 6-sulfate</p> Signup and view all the answers

    What is the repeating disaccharide unit found in Hyaluronic acid?

    <p>D-Glucoronic acid and D-Glucosamine</p> Signup and view all the answers

    Which glycosaminoglycan is most associated with the aorta and the lung?

    <p>Heparan Sulfate</p> Signup and view all the answers

    Which glycosaminoglycan has low levels of interaction primarily with collagen type I?

    <p>Dermatan Sulfate</p> Signup and view all the answers

    Which repeating disaccharide unit characterizes Chondroitin 4-sulfate?

    <p>D-Glucoronic acid and D-Galactosamine</p> Signup and view all the answers

    Which glycosaminoglycan is unique to the cornea?

    <p>Keratan Sulfate (cornea)</p> Signup and view all the answers

    What type of acid forms the repeating unit for Dermatan Sulfate?

    <p>D-Glucoronic acid or L-iduronic acid</p> Signup and view all the answers

    What is the primary function of glycosaminoglycans in relation to collagen?

    <p>To aid in electrostatic interactions</p> Signup and view all the answers

    Study Notes

    Types of Fibers in Connective Tissue

    • Hydroxyproline and Hydroxylysine: Byproducts of proline and lysine hydroxylation, important for collagen stability.
    • Main Types of Fibers:
      • Collagen fibers
      • Reticular fibers
      • Elastic fibers

    Collagen Fiber Structure

    • Tropocollagen: Protein unit that polymerizes to form collagen fibrils, consisting of three intertwined polypeptide chains in a triple helix.
    • Distribution: Collagen distributes unevenly, determining the properties of connective tissue.
    • Types of Collagen: 28 types are known; the most common include types I, II, III, IV, V, VII, IX, XII, XIV.

    Aggregation and Packing of Collagen

    • Microfibrillar Subunits: Tropocollagen molecules aggregate to form microfibrils, packed to create collagen fibrils, enhanced by hydrogen bonds and hydrophobic interactions.
    • Covalent Cross-links: Strengthened through covalent bonds catalyzed by lysyl oxidase.

    Characteristics of Collagen Fibrils

    • Appearance: Thin and elongated structures, variable diameters (20 to 90 nm), with striations indicating periodicity (64 nm).
    • Composition: Includes an amorphous central region containing elastin, surrounded by a sheath of 14 nm tubular microfibrils.

    Elastin

    • Production: Secreted as proelastin (70,000 MW), polymerizes into elastin, mainly produced by fibroblasts.
    • Properties: Resistant to boiling and extraction, touted for its unique nonpolar peptide chains stabilizing its structure.

    Cells in Connective Tissue

    • Mast Cells:

      • Oval to round (20-30 µm) cells, cytoplasm filled with basophilic granules.
      • Release leukotrienes, contain heparin (connective tissue mast cells) or chondroitin sulfate (mucosal mast cells).
      • Possess specific receptors for IgE, playing a role in immune responses.

    • Plasma Cells:

      • Large, oval-shaped cells with basophilic cytoplasm rich in rough endoplasmic reticulum (RER).
      • Responsible for antibody synthesis, with eccentrically located nuclei.

    • Adipose Cells:

      • Specialized for neutral fat storage and thermoregulation.
      • Help maintain body temperature, influenced by protein types, fiber characteristics, and ground substance in connective tissue.

    Types of Connective Tissues

    • Connective Tissue Proper:
      • Loose Connective Tissue:
        • Also known as areolar tissue, fills spaces between fibers and muscle sheaths, supports epithelial tissue.
      • Dense Connective Tissue: Dense fiber arrangements, forms tendons and ligaments.

    Glycosaminoglycans (GAGs)

    • Hyaluronic Acid: Found in umbilical cord, synovial fluid, cartilage.
    • Chondroitin Sulfates (4 & 6): High levels in cartilage, bone, and skin, with varying interactions with collagen types II and I.
    • Dermatan and Heparan Sulfates: Found in skin, aorta, and other tissues, with intermediate interactions mainly with collagen types III and IV.
    • Keratan Sulfate: Present in cornea and cartilage.

    Summary of Connective Tissue Function

    • Connective tissue plays crucial roles in structural support, immune response, and tissue repair and regulation.

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    [HISTO]LEC_006_CONNECTIVE TISSUES.pdf

    Description

    Explore the properties and types of fibers while delving into the roles of hydroxyproline and hydroxylysine in biochemical processes. This quiz covers key concepts related to the hydroxylation of proline and lysine and their importance in biological systems.

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