Extracellular Matrix and Glycosaminoglycans
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Questions and Answers

Which characteristic distinguishes hyaluronic acid from other glycosaminoglycans (GAGS)?

  • It is non-sulfated. (correct)
  • It contains up to 50,000 disaccharide units.
  • It has covalently bound disaccharides.
  • It is made up of GlcNAc and GICA.

What is a primary cause of Hurler's syndrome?

  • Accumulation of heparan sulfate.
  • X-linked inheritance pattern.
  • Deficiency of N-acetyltransferase.
  • Deficiency of alpha-L-iduronidase. (correct)

Which of the following features is NOT characteristic of Dysotosis Multiplex?

  • Excessive growth and no mental retardation. (correct)
  • Lipid-like substance deposition in tissues.
  • Abnormal facial features.
  • Severe developmental abnormalities in cartilage.

How does Hunter syndrome differ from Hurler's syndrome?

<p>The enzyme deficiency in Hunter syndrome is iduronate sulfatase. (B)</p> Signup and view all the answers

Which statement accurately describes Sanfilippo syndrome?

<p>It involves a deficiency of one of four enzymes, predominantly hydrolases. (A)</p> Signup and view all the answers

Which glycosaminoglycan is unique for lacking uronic acid in its structure?

<p>Keratan sulfate (C)</p> Signup and view all the answers

What is the primary role of chondroitin sulfate in cartilage?

<p>Forms proteoglycans aggregates (D)</p> Signup and view all the answers

Which of the following statements about heparin is correct?

<p>It serves as an anticoagulant. (D)</p> Signup and view all the answers

Which glycosaminoglycan serves a key function in maintaining corneal transparency?

<p>Keratan sulfate I (A)</p> Signup and view all the answers

What is the main function of hyaluronic acid in the joints?

<p>Acts as a shock absorber and lubricant (D)</p> Signup and view all the answers

What is the significance of the highly hydrated structure of hyaluronic acid?

<p>Enhances shock absorption (D)</p> Signup and view all the answers

Which of the following is true about dermatan sulfate?

<p>Contains L-iduronic acid + Glucosamine. (C)</p> Signup and view all the answers

What is the enzyme defect associated with Mucopolysaccharidosis I (Hurler Syndrome)?

<p>α-L-iduronidase (A)</p> Signup and view all the answers

Which glycosaminoglycan is primarily involved in the structure of the extracellular matrix?

<p>Heparan sulfate (A)</p> Signup and view all the answers

Which glycosaminoglycans are primarily accumulated in Mucopolysaccharidosis II (Hunter Syndrome)?

<p>Dermatan sulfate and heparan sulfate (A)</p> Signup and view all the answers

Which of the following is a characteristic of keratan sulfate II?

<p>Present in loose connective tissues. (A)</p> Signup and view all the answers

What distinguishes hyaluronidase in its function?

<p>It degrades β(1→4) linkages in hyaluronic acid. (C)</p> Signup and view all the answers

What is the primary characteristic of Sanfilippo Syndrome?

<p>Severe mental retardation with little structural change (D)</p> Signup and view all the answers

Which enzyme deficiency causes Morquio Syndrome?

<p>Galactose-6-sulfatase (D)</p> Signup and view all the answers

Which of the following is NOT a symptom associated with Hurler Syndrome?

<p>Clear vision (D)</p> Signup and view all the answers

In the context of cancer, how does hyaluronic acid contribute to tumor spread?

<p>By promoting cell migration through ECM (B)</p> Signup and view all the answers

What characterizes the structural aspect of glycosaminoglycans (GAGs)?

<p>Long chains of sugar carbohydrates (B)</p> Signup and view all the answers

Which syndrome is characterized as an X-linked disorder?

<p>Hunter Syndrome (A)</p> Signup and view all the answers

The primary defect in Mucopolysaccharidosis VI (Maroteaux-Lamy's Syndrome) affects which enzyme?

<p>N-acetylglucosamine-4-sulfatase (C)</p> Signup and view all the answers

What underlying issue leads to the symptoms of chondrodystrophies?

<p>Defect in the sulphation of growing GAG chains (D)</p> Signup and view all the answers

Which of the following correctly describes the structure of glycosaminoglycans?

<p>Long unbranched chains composed of repeating disaccharide units (B)</p> Signup and view all the answers

Which of the following is NOT a type of mucopolysaccharidosis?

<p>Klinefelter syndrome (C)</p> Signup and view all the answers

What is a characteristic symptom of Hurler syndrome?

<p>Enlarged head and facial features (B)</p> Signup and view all the answers

Which glycosaminoglycan is typically associated with lubrication in joints?

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

What is a common physical symptom seen in Sanfilippo syndrome?

<p>Enlarged spleen and liver (B)</p> Signup and view all the answers

Which of the following details is true about Hunter syndrome?

<p>It has a milder phenotype compared to Hurler syndrome. (C)</p> Signup and view all the answers

What is the primary role of glycosaminoglycans in connective tissues?

<p>To support cellular and fibrous components (D)</p> Signup and view all the answers

What kind of enzymes are responsible for the degradation of glycosaminoglycans?

<p>Lysosomal hydrolases (B)</p> Signup and view all the answers

Which of the following accurately describes an outcome of hereditary enzyme deficiencies related to mucopolysaccharidoses?

<p>Accumulation of complex carbohydrates in tissues (C)</p> Signup and view all the answers

What are the repeating units that constitute the structure of glycosaminoglycans?

<p>Amino sugar and uronic sugar (A)</p> Signup and view all the answers

Which type of glycosaminoglycan is primarily involved in the structural composition of cartilage?

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

What is a common characteristic of Hurler syndrome?

<p>Accumulation of dermatan and heparan sulfate (C)</p> Signup and view all the answers

Which enzyme deficiency is associated with Hunter syndrome?

<p>Iduronate-2-sulfatase (D)</p> Signup and view all the answers

Which of the following symptoms is NOT typically associated with Sanfilippo syndrome?

<p>Corneal clouding (A)</p> Signup and view all the answers

Which type of glycosaminoglycan is NOT commonly found in the extracellular matrix?

<p>Laminin (A)</p> Signup and view all the answers

What is the main biochemical function of glycosaminoglycans within the extracellular matrix?

<p>Provide structural framework (A)</p> Signup and view all the answers

Which type of glycosaminoglycan is significant for its ability to bind large amounts of water?

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

Flashcards

Glycosaminoglycans (GAGs)

Long, unbranched polysaccharide chains with repeating disaccharide units (sugar + sugar).

GAG Structure

Repeating disaccharide units of uronic acid and glycosamine, forming long chains.

GAG Function

GAGs bind water to form a gel-like matrix supporting surrounding cells.

Extracellular Matrix (ECM)

A collection of molecules secreted by cells that provides structural and biochemical support.

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ECM Composition

Made of fibrous proteins (collagen, elastin) and glycosaminoglycans (GAGs), forming a complex mesh.

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Proteoglycan

A protein bonded to a glycosaminoglycan (GAG).

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Uronic Acid

A type of sugar in GAGs.

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Glycosamine

A type of sugar found in GAGs

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Chondroitin Sulfate Function

A major GAG in cartilage, tendons, and ligaments, forming proteoglycan aggregates, crucial for structural integrity and weight-bearing properties.

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Keratan Sulfate Types

Two types (KSI and KSII) of Keratan Sulfate, KSI found in the cornea, maintaining transparency, while KSII is in loose connective tissues.

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Heparin's Role

An intracellular GAG, mainly a natural anticoagulant, found in mast cells.

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Dermatan Sulfate Location

GAG found in skin, heart valves, and blood vessels, contributing to shape and structure.

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Heparan Sulfate Location

An extracellular GAG, a key component of basement membranes and cell surfaces.

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Hyaluronic Acid Composition

A sulfate-free GAG composed of glucoronic acid and glucosamine, found widely in tissues and fluids.

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Hyaluronic Acid Function

A lubricant and shock absorber in joints, influencing cell migration and wound healing.

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Hyaluronic Acid Structure

Long chains of repeating disaccharide units of GIcA and GlcNAc, crucial in its function.

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GAG Anticoagulant

Heparin's function as an anticoagulant.

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GAG roles in tissues

GAGs form an important component of connective tissues like cartilage, tendons, ligaments, and vitreous humor; they determine charge selectiveness of the renal glomerulus.

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What are Glycosaminoglycans?

Long, unbranched chains of repeating sugar units (disaccharides), found in connective tissues like cartilage and ligaments.

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What are Glycosaminoglycans made of?

Glycosaminoglycans are made up of repeating disaccharide units, which are two sugars linked together.

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What are some examples of Glycosaminoglycans?

Some examples of Glycosaminoglycans include chondroitin sulfate, keratan sulfate, dermatan sulfate, hyaluronic acid, heparin, and heparan sulfate.

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What is the function of Glycosaminoglycans?

Glycosaminoglycans provide structural support, bind water, and act as lubricants in connective tissues.

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How do Glycosaminoglycans bind water?

Glycosaminoglycans are negatively charged, attracting positively charged water molecules, creating a gel-like substance.

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What are the effects of Glycosaminoglycan deficiency?

Deficiencies in Glycosaminoglycans can lead to a group of genetic disorders called Mucopolysaccharidoses.

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What are Mucopolysaccharidoses?

A group of genetic disorders caused by the inability to break down Glycosaminoglycans, leading to their build-up in the body.

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What are some symptoms of Mucopolysaccharidoses?

Symptoms include enlarged head, lips, cheeks, tongue, and nose, frequent respiratory infections, and enlarged liver and spleen.

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What are some examples of Mucopolysaccharidoses?

Examples include Hurler syndrome, Hunter syndrome, Sanfilippo syndrome, and Sly syndrome.

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How are Mucopolysaccharidoses diagnosed?

Diagnosis is often made through genetic testing and observation of physical symptoms.

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Hyaluronidase

An enzyme found in semen that breaks down the gel surrounding the egg, allowing sperm to penetrate. This is essential for fertilization.

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Hyaluronic Acid vs. Other GAGs

Hyaluronic acid stands out from other GAGs because it lacks sulfation, is not covalently bound to proteins, and has unique monomeric units (GICA and GlcNAc).

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Mucopolysaccharidoses (MPS)

A group of rare genetic disorders caused by the body's inability to break down glycosaminoglycans (GAGs), leading to their accumulation and damaging effects on bone, cartilage, and mental function.

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Hurler's Syndrome

A type of MPS caused by a deficiency in the alpha-L-iduronidase enzyme, leading to the buildup of heparan sulfate and dermatan sulfate, resulting in physical and mental developmental delays.

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Hunter's Syndrome

Similar to Hurler's syndrome, but with a deficiency in iduronate sulfatase and X-linked inheritance, causing a buildup of GAGs and similar developmental issues.

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Enzyme deficiency

A missing or malfunctioning enzyme that is crucial for breaking down specific molecules, especially glycosaminoglycans (GAGs) in lysosomes

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GAG accumulation

A buildup of glycosaminoglycans (GAGs) within cells and tissues, leading to organ damage and various symptoms.

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Hurler Syndrome (MPS I)

A type of MPS caused by a deficiency in a-L-Iduronidase, leading to buildup of dermatan sulfate and heparan sulfate. Symptoms include mental retardation and structural changes.

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Hunter Syndrome (MPS II)

X-linked MPS disorder caused by a deficiency in iduronate sulfatase, resulting in the accumulation of heparan sulfate and dermatan sulfate.

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Sanfilippo Syndrome (MPS III)

MPS type where a breakdown enzyme is lacking, affecting heparan sulfate, leading to severe mental retardation but less structural changes.

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Morquio Syndrome (MPS IV)

Characterized by a deficiency in galactose-6-sulfatase or a beta-galactosidase. Accumulates Keratan sulfate, marked by normal intelligence and severe structural deformities.

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Lysosomal storage diseases

Group of inherited metabolic disorders where enzymes needed to break down substances in lysosomes are missing or malfunctioning.

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Hyaluronic acid

A type of GAG that is involved in tumor cell migration to help in tumor spread.

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Study Notes

Extra Cellular Matrix (ECM)

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

Glycosaminoglycans (GAGs)

  • GAGs are large complexes of negatively charged heteropolysaccharide chains.
  • They have a high water-binding capacity, forming a gel-like matrix.
  • GAGs act as a cushion against mechanical shock.
  • GAGs help lubricate joints.
  • GAGs provide flexibility (elasticity) to cartilage.

Composition of ECM

  • ECM is a mesh of fibrous proteins and GAGs.
  • Major classes of biomolecules in ECM include:
    • Structural proteins (collagen, elastin, fibrillin)
    • Specialized proteins (fibronectin, laminin, fibrillin)
    • Proteoglycans (proteins bonded to mucopolysaccharides)

Functions of ECM

  • Binding and packing of tissues (connective tissue proper).
  • Connecting, anchoring and supporting the body and its organs.
  • Transport of metabolites between capillaries and tissues.
  • Essential for processes like growth, wound healing, and fibrosis (scarring).
  • Defense against infection (via ground substance and cells).
  • Repair of injury (via cell proliferation and fiber formation).
  • Fat storage.

Classification of GAGs

  • Sulfate-free GAGs (e.g., hyaluronic acid)
  • Sulfate-containing GAGs (e.g., chondroitin sulfate, keratan sulfate, heparin, heparan sulfate, dermatan sulfate)

Structure of GAGs

  • Linear polymers.
  • Heteropolysaccharide composed of repeating disaccharide units.
  • Uronic acid and glycosamine are the repeating units in most GAGs.

Hyaluronic Acid

  • A sulfate-free GAG.
  • Contains D-glucouronic acid and N-acetylglucosamine.
  • Forms a viscous, clear solution ideal for lubrication.
  • Important for structural support in tissues.
  • Plays a role in cell migration and wound repair.
  • Found in synovial fluid, vitreous humor, and connective tissues.

Mucopolysaccharidoses (MPS)

  • Rare inborn errors in the degradation of GAGs.
  • Hereditary disorders (often autosomal recessive).
  • Result in the accumulation of GAGs in various tissues.
  • MPS lead to a range of symptoms including skeletal and extracellular matrix deformities, and mental retardation.

Dysotosis Multiplex

  • Major features include severe abnormalities in the development of cartilage and bone.
  • Significant skeletal changes and the deposition of a lipid-like substance in many body tissues.
  • Often associated with mental retardation and organomegaly.
  • Also characterized by abnormal facial features, hearing/vision and cardiovascular issues.
  • This category covers conditions that arise from missing or insufficient GAG-breaking enzymes.
  • These conditions often lead to the accumulation of GAGs in affected tissues, resulting in a range of symptoms.

Association of GAGs with cancer

  • Tumor cells may exhibit increased production of hyaluronic acid, aiding in cell migration within ECM.
  • Heparan sulfate may be less present on the surface of tumor cells, potentially impacting their adhesiveness.

Take Home Messages

  • GAGs have a variety of functions related to lubrication, support, and cell interactions.
  • Their accumulation or deficiency can cause serious diseases.
  • Understanding the structure and function of GAGs is important for various medical fields.

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Description

This quiz covers the essential concepts of the extracellular matrix (ECM), including its composition, functions, and the role of glycosaminoglycans (GAGs). Learn how ECM provides support to cells and contributes to various physiological functions. Test your knowledge on structural proteins and the significance of these biomolecules in connective tissues.

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