Fibrous Proteins
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Questions and Answers

Which type of proteins have a long cylindrical shape and low solubility in water?

  • Globular proteins
  • Structural proteins
  • Fibrous proteins (correct)
  • Enzymatic proteins
  • What is a common characteristic of fibrous proteins?

  • Enzymatic activity
  • High solubility in water
  • Irregular secondary structure
  • Regular secondary structure (correct)
  • Which of the following is an example of a fibrous protein?

  • Collagen (correct)
  • Amylase
  • Hemoglobin
  • Insulin
  • Which organ/tissue has collagen fibers that are arranged at an angle to each other to resist mechanical shear from any direction?

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

    How many distinct types of collagen are found in the human body?

    <p>More than 25</p> Signup and view all the answers

    What is the main function of collagen in the human body?

    <p>To provide structural strength</p> Signup and view all the answers

    Which type of collagen is a major component of the basal lamina?

    <p>Type IV</p> Signup and view all the answers

    What is the repeating banding pattern observed in collagen fibrils?

    <p>64 nm</p> Signup and view all the answers

    Which type of collagen is involved in Classical Ehlers Danlos Syndrome?

    <p>Type V</p> Signup and view all the answers

    Which type of collagen is found in the dermis, bone, tendon, dentin, fascias, sclera, organ capsules, and fibrous cartilage?

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

    Which type of collagen is involved in the structural maintenance of expansible organs such as smooth muscle, endoneurium, arteries, uterus, liver, spleen, kidney, and lung?

    <p>Type III</p> Signup and view all the answers

    Which type of collagen is a major component of the basal lamina in epithelial and endothelial tissues?

    <p>Type IV</p> Signup and view all the answers

    Which amino acid is frequently found in the X position of the repeating triplets in collagen?

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

    What is the primary role of glycine in the collagen helix?

    <p>To provide flexibility to the helix</p> Signup and view all the answers

    How many residues are there per turn in the helices of collagen?

    <p>3</p> Signup and view all the answers

    Which amino acid is responsible for conferring rigidity to the collagen triple helix?

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

    Which amino acid is involved in H-bond formation that helps to stabilize the collagen triple helix?

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

    Which amino acid is the site of attachment of carbohydrate moieties in collagen?

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

    Which modification is essential for enhancing the stability and function of collagen chains?

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

    What facilitates the assembly of collagen chains into a triple helical structure?

    <p>Molecular chaperones</p> Signup and view all the answers

    Where are the mature collagen molecules secreted into?

    <p>Extracellular matrix</p> Signup and view all the answers

    Which of the following is required for the post-translational hydroxylation of proline and lysine in collagen synthesis?

    <p>Molecular oxygen, iron, and Vitamin C</p> Signup and view all the answers

    Which process involves the glycosylation of hydroxylysine residues in collagen synthesis?

    <p>O glycosidic bonds to galactose and glucose</p> Signup and view all the answers

    What is the role of Vitamin C (Ascorbate) in collagen synthesis?

    <p>It is required for the post-translational hydroxylation of proline and lysine</p> Signup and view all the answers

    Which direction does the winding of the triple helix occur in collagen formation?

    <p>From the carboxyl terminus towards the amino terminus</p> Signup and view all the answers

    What initiates the winding of the triple helix in collagen formation?

    <p>Folding of carboxy-terminal globular domains</p> Signup and view all the answers

    What is the order of events in collagen formation?

    <p>Formation of disulfide bonds, folding of carboxy-terminal globular domains, winding of the triple helix</p> Signup and view all the answers

    Which organelle is responsible for the release of completed procollagen from the cell?

    <p>Golgi apparatus</p> Signup and view all the answers

    What is the role of N- and C- procollagen peptidases in collagen formation?

    <p>They remove the terminal pro-peptides, releasing the triple helix tropocollagen molecule</p> Signup and view all the answers

    How is completed procollagen released from the cell?

    <p>Via exocytosis</p> Signup and view all the answers

    Which enzyme catalyzes the conversion of lysine residues into its aldehyde derivative allysine in collagen fibrils?

    <p>Lysyl oxidase</p> Signup and view all the answers

    What is the primary role of cross-linking in the fibrillar array of collagen molecules?

    <p>To enhance the tensile strength</p> Signup and view all the answers

    What is the function of lysyl oxidase in collagen synthesis?

    <p>To promote the formation of cross-links</p> Signup and view all the answers

    Which of the following is a consequence of the overlapping individual triple strands in collagen fibril formation?

    <p>Regular axial periodic pattern</p> Signup and view all the answers

    What is the key characteristic of the mesoscopic structures formed during collagen fibril formation?

    <p>Micron length</p> Signup and view all the answers

    What is the significance of the staggered arrangement of collagen triple strands in fibril formation?

    <p>Contributes to D-banding pattern</p> Signup and view all the answers

    Which enzyme is responsible for the degradation of collagen during tissue remodeling or in response to growth/injury of tissue?

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

    What happens to collagen during degradation?

    <p>It is broken into smaller fragments</p> Signup and view all the answers

    What is the effect of a mutation that interferes with the ability of collagen to form cross-linked fibrils?

    <p>It almost certainly affects the stability of collagen</p> Signup and view all the answers

    Which of the following is NOT a function of collagen in maintaining homeostasis?

    <p>Initiating the formation of blood clots</p> Signup and view all the answers

    What is the role of collagen in wound healing?

    <p>Serving as a scaffold for cellular migration</p> Signup and view all the answers

    How does collagen contribute to vascular health?

    <p>Providing structural support to arterial walls</p> Signup and view all the answers

    Which type of collagen is primarily affected in Classical Ehlers Danlos Syndrome?

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

    Which type of collagen is primarily affected in the Vascular type of Ehlers Danlos Syndrome?

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

    Which enzyme is responsible for the pathogenesis of the Kyphoscoliotic type of Ehlers Danlos Syndrome?

    <p>Lysyl hydroxylase</p> Signup and view all the answers

    Which type of Ehlers Danlos Syndrome is the most common?

    <p>Hypermobile EDS (hEDS)</p> Signup and view all the answers

    What is the genetic basis for Classical EDS (cEDS)?

    <p>COL5A1, COL5A2</p> Signup and view all the answers

    Which type of collagen is primarily affected in Vascular EDS (vEDS)?

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

    Which type of Osteogenesis Imperfecta is characterized by fractures secondary to minor trauma in infancy?

    <p>Type I - Osteogenesis imperfecta tarda</p> Signup and view all the answers

    Which type of Osteogenesis Imperfecta is more severe and results in death in utero or neonatally from pulmonary hypoplasia?

    <p>Type II - Osteogenesis imperfecta congenita</p> Signup and view all the answers

    Which type of Osteogenesis Imperfecta is characterized by similar mutations at the Gly position, causing deformities but not lethality?

    <p>Type III - Osteogenesis imperfecta</p> Signup and view all the answers

    Which of the following is a symptom of scurvy, a condition resulting from vitamin C deficiency?

    <p>All of the above</p> Signup and view all the answers

    Which protein gives tissues and organs the capacity to stretch without tearing?

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

    Where is elastin found in the body?

    <p>All of the above</p> Signup and view all the answers

    Which statement about collagen is correct?

    <p>Collagen has a repeating structure of (Gly-X-Y)n.</p> Signup and view all the answers

    What is the primary function of elastin in the human body?

    <p>To allow stretching of tissues without tearing.</p> Signup and view all the answers

    Where is tropoelastin synthesized in the cell?

    <p>In the rough endoplasmic reticulum.</p> Signup and view all the answers

    Which protein is responsible for elastogenesis?

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

    What is the molecular weight of elastin?

    <p>64 - 66 kDa</p> Signup and view all the answers

    Which cross-link is unique to elastin?

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

    Which of the following characteristics is NOT exhibited by mature, extracellular elastin?

    <p>Has a very low turnover rate</p> Signup and view all the answers

    What is the primary function of mature, extracellular elastin?

    <p>To provide structural support to organs and tissues</p> Signup and view all the answers

    Which of the following is a key characteristic of the conformation of mature, extracellular elastin?

    <p>Random coil conformations</p> Signup and view all the answers

    Which enzyme is responsible for the degradation of elastin in the extracellular space?

    <p>Neutrophil elastase</p> Signup and view all the answers

    What is the clinical significance of emphysema in individuals with genetic absence of α1-antitrypsin?

    <p>Emphysema is more severe in these individuals</p> Signup and view all the answers

    What is the primary symptom of emphysema?

    <p>Shortness of breath</p> Signup and view all the answers

    Which of the following is NOT a characteristic of α-keratins?

    <p>They are found in the outer epidermal layer of mammals</p> Signup and view all the answers

    What is the result of the tandem repetition of a 7-residue segment in α-keratins?

    <p>Formation of a super-helical structure containing 2 polypeptide chains</p> Signup and view all the answers

    What is the role of the polar edge in α-keratins?

    <p>Interacts with water on the outside of the superhelix</p> Signup and view all the answers

    Which structure is formed when two keratin α chains combine in a coiled coil formation?

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

    How many protofilaments combine to form a filament (protofibril)?

    <p>4</p> Signup and view all the answers

    What is the primary cause of changes in hair wave appearance during permanent waving?

    <p>Breakage of disulfide bonds</p> Signup and view all the answers

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