MED100-I Medical Biology: Extracellular Matrix
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MED100-I Medical Biology: Extracellular Matrix

This quiz covers the extracellular matrix (ECM) component of tissues, including its molecular components and functions.

Created by
@FatihSultanMehmet

Questions and Answers

What percentage of total proteins in the human body does collagen account for?

30%

What is the typical structure of collagen proteins?

Trimer

What is the repeated sequence of amino acids found in collagen?

Glycine-X-Y

What is the result of collagen cross-linking and deposition during tumorigenesis?

<p>Stiffer ECM, disrupted tissue morphogenesis, and promoted signaling</p> Signup and view all the answers

What is the function of matrix metalloproteinases in wound healing?

<p>Degrading collagen</p> Signup and view all the answers

Which cell types produce matrix metalloproteinases during wound healing?

<p>Fibroblasts, inflammatory cells, chondrocytes, osteoblasts, and osteoclasts</p> Signup and view all the answers

What is the consequence of mutations in collagen genes?

<p>Chondrodysplasia, osteogenesis imperfecta, Alport syndrome, Ehlers-Danlos syndrome, and dystrophic EB</p> Signup and view all the answers

What is the role of proteoglycans in the extracellular matrix?

<p>Cushioning cells and binding extracellular molecules</p> Signup and view all the answers

What are the two main components of all tissues?

<p>Cellular and extracellular components</p> Signup and view all the answers

What is the matrisome?

<p>The ensemble of proteins that compose the ECM and associated proteins that covalently modify the ECM</p> Signup and view all the answers

What is the function of the ECM in tissues?

<p>To fill the spaces between cells and bind cells and tissues together</p> Signup and view all the answers

What is an example of a type of extracellular matrix?

<p>Basal lamina</p> Signup and view all the answers

What is the composition of the ECM in tendons?

<p>High proportion of fibrous proteins</p> Signup and view all the answers

What is the function of glycocalyx?

<p>To act as a polysaccharide rich coat on the plasma membrane</p> Signup and view all the answers

What is the composition of the ECM in bone?

<p>High concentration of calcium phosphate crystals</p> Signup and view all the answers

What is the purpose of proteases secreted by cancer cells?

<p>To digest proteins of the ECM</p> Signup and view all the answers

What is the structure of basal laminae?

<p>Sheetlike and firm</p> Signup and view all the answers

What is the main function of the dermis?

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

What is the primary function of the basement membrane?

<p>To provide cell attachment</p> Signup and view all the answers

What is a characteristic of ECM in adult organisms?

<p>It exhibits slow turnover</p> Signup and view all the answers

What is the role of the ECM in angiogenesis?

<p>To modulate the formation of new blood vessels</p> Signup and view all the answers

What is the role of the ECM in cell signaling?

<p>It acts as a reservoir for growth factors</p> Signup and view all the answers

What type of matrix needs to form rapidly and in the correct location in response to injury?

<p>Blood clot</p> Signup and view all the answers

Why is the ECM important in the healing of fractures or wounds?

<p>It retains the capacity to respond to changes</p> Signup and view all the answers

What is the single most abundant protein in animal tissues?

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

What is the main function of glycosaminoglycans in the ECM?

<p>To absorb water and resist compression</p> Signup and view all the answers

What is the characteristic of glycosaminoglycans that allows them to attract large amounts of water?

<p>Their negative charge</p> Signup and view all the answers

What is the main function of hyaluronic acid in joints?

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

What is the characteristic of proteoglycans?

<p>They are composed of sulphated GAGs covalently linked to a polypeptide chain</p> Signup and view all the answers

What is the molecular weight of aggrecan, a major constituent of cartilage?

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

What is the characteristic of decorin?

<p>It has a molecular weight of 40 kDa</p> Signup and view all the answers

What is the space occupied by a single hyaluronic acid molecule, swollen with water?

<p>10^7 nm^3</p> Signup and view all the answers

Study Notes

Extracellular Matrix (ECM)

  • All tissues consist of two components: cellular component and extracellular component
  • ECM comprises specialized structures that constitute the ECM
  • Molecular components of ECM are secreted and assembled by cells of the tissue

Composition of ECM

  • ECM consists of a variety of secreted proteins and polysaccharides
  • Proteins and polysaccharides in ECM are associated with the plasma membrane
  • Glycocalyx is a polysaccharide-rich coat on the plasma membrane of endothelial cells or the apical membrane of intestinal epithelial cells

Matrix Structural Proteins

  • Matrix structural proteins include tough fibrous proteins, adhesion proteins, and proteoglycans
  • Tendons contain a high proportion of fibrous proteins, while cartilage contains a high concentration of polysaccharides that form a firm compression-resistant gel
  • Bone ECM is hardened by deposition of calcium phosphate crystals
  • Sheetlike structure of basal laminae results from a matrix composition that differs from that found in connective tissues

Collagen

  • Collagen is the most abundant protein in the extracellular matrix
  • Secreted mainly by fibroblasts, it accounts for up to 30% of the total proteins in human bodies
  • Collagen comprises a family of 28 genetically distinct proteins
  • Principal structural elements of all connective tissues are characterized by the presence of a repeated sequence of three amino acids: a tripeptide (glycine-X-Y)
  • All collagens are trimers in which at least some and often most of the protein chains are involved in forming a triple helix

Functions of ECM

  • ECM fills the spaces between cells and binds cells and tissues together
  • ECM provides structural integrity, mechanical strength, and resilience
  • ECM is involved in cell signaling, providing the basis for signals transmitted to cells by adhesion receptors that bind to its components
  • ECM acts as a reservoir for growth factors that also bind reversibly to its constituents

Glycosaminoglycans (GAGs) and Proteoglycans

  • Glycosaminoglycans (GAGs) are carbohydrate chains that are usually linked to proteins to form proteoglycans
  • GAGs are strongly negatively charged and attract cations, which are osmotically active and thus attract large amounts of water
  • GAGs absorb water and resist compression, filling large volumes of space and resisting compressive forces
  • Hyaluronic acid (HA) is a nonsulphated GAG that is widely distributed in tissues and facilitates cell migration in embryonic development and wound healing

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