Plasma Membrane 2
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Questions and Answers

What is the main factor that determines the structure and flexibility of the lipid bilayer?

  • Protein content
  • Lipid composition (correct)
  • Temperature changes
  • Cell size

    • In the context of biological membranes, what does 'flexibility' refer to?

  • Ability to resist pH changes
  • Ability to change shape without becoming leaky (correct)
  • Ability to produce energy
  • Ability to replicate quickly

    • What is the function of cholesterol in the cell membrane?

  • Store genetic information
  • Accelerate protein synthesis
  • Act as a 'fluidity buffer' (correct)
  • Facilitate cell division

    • Which type of preparations were effective in demonstrating the free diffusion of individual lipid molecules within lipid bilayers?

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

    What contributes to the fluidity of biological membranes through noncovalent interactions?

    <p>Lipids in the bilayer</p> Signup and view all the answers

    Why is the ability of a lipid bilayer to flow important?

    <p>For flexibility and functionality of cell membranes</p> Signup and view all the answers

    What is the main purpose of using black membranes across a hole in a partition between two compartments?

    <p>To measure the permeability properties of synthetic membranes</p> Signup and view all the answers

    Which type of diffusion happens rarely across the lipid bilayer?

    <p>Flip-flop diffusion</p> Signup and view all the answers

    What facilitates the catalysis of trans-bilayer movement of lipids within the cell membrane?

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

    How do temperature and hydrocarbon tail size influence phospholipid movement within the lipid bilayer?

    <p>Higher temperature speeds up movement</p> Signup and view all the answers

    What is the purpose of adjusting the fatty acid content of membranes by some organisms in response to environmental temperature fluctuations?

    <p>To maintain a relatively constant fluidity</p> Signup and view all the answers

    At what characteristic temperature does membrane phase transition occur between the liquid-crystalline and paracrystalline state?

    <p>+37°C</p> Signup and view all the answers

    What type of proteins fill the space between fibers and cells in the Ground Substance?

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

    Which type of protein is rich in proline and glycine amino acids and forms glycosylated fibrils?

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

    Where does protein glycosylation occur in the ECM?

    <p>In the Ground Substance</p> Signup and view all the answers

    Which ECM macromolecule gives tissues their elasticity and is hydrophobic?

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

    Which protein in the ECM forms a cross-linked network allowing for stretching and recoiling like a rubber band?

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

    Which ECM component has specific binding sites for other macromolecules and for cell surface receptors?

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

    What is the primary role of fibronectin?

    <p>Playing a key role in tissue repair</p> Signup and view all the answers

    Which statement best describes the composition of laminin?

    <p>Made of three long polypeptide chains held by disulfide bonds</p> Signup and view all the answers

    What is the main function of integrins in cell membranes?

    <p>Facilitating cell adhesion and mediating cellular signals</p> Signup and view all the answers

    Which characteristic best describes the basal lamina?

    <p>Essential component of all epithelia</p> Signup and view all the answers

    How do integrins contribute to cell function?

    <p>Link cytoskeleton filaments with the ECM</p> Signup and view all the answers

    What is the significance of fibronectin in embryogenesis?

    <p>Playing a crucial role in tissue repair during embryonic development</p> Signup and view all the answers

    What is the main factor that determines the fluidity of cell membranes?

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

    How do unsaturated fatty acids affect the melting point of a membrane?

    <p>Decrease it</p> Signup and view all the answers

    What is the function of cholesterol in cell membranes at high temperatures?

    <p>Stiffen the bilayer</p> Signup and view all the answers

    What effect does a higher content of saturated fatty acids have on a lipid bilayer?

    <p>Forms paracrystalline structures</p> Signup and view all the answers

    In what way do unsaturated fatty acids influence membrane structure?

    <p>Promote lipid movement</p> Signup and view all the answers

    Which type of connective tissue is characterized by mainly collagen fibers and bone minerals in its ECM?

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

    What is the primary function of fibroblasts in the ECM?

    <p>Secrete ECM macromolecules</p> Signup and view all the answers

    What is the primary role of cholesterol in the lipid bilayer at low temperatures?

    <p>Increase fluidity</p> Signup and view all the answers

    What type of connective tissue matrix contains gels of polysaccharides and fibrous proteins?

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

    How do cis-double bonds in unsaturated fatty acids affect the lipid bilayer structure?

    <p>Inhibit membrane rigidity</p> Signup and view all the answers

    What determines the structure and flexibility of the lipid bilayer in biological membranes?

    <p>Lipid composition</p> Signup and view all the answers

    How does the extracellular matrix contribute to cell physiology?

    <p>By supporting cellular structures</p> Signup and view all the answers

    Which component acts as a 'fluidity buffer' in the cell membrane?

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

    What is the primary factor influencing the flow ability of lipid bilayers in biological membranes?

    <p>Temperature changes</p> Signup and view all the answers

    How do temperature changes impact the structure and flexibility of the lipid bilayer?

    <p>By affecting lipid fluidity</p> Signup and view all the answers

    In biological membranes, what contributes to the ability of lipids to change shape without losing integrity?

    <p>Flexibility from noncovalent lipid interactions</p> Signup and view all the answers

    What is the main difference between transversal diffusion and lateral diffusion in the lipid bilayer?

    <p>Transversal diffusion occurs rarely, while lateral diffusion happens readily and rapidly.</p> Signup and view all the answers

    Which characteristic influences the fluidity of a lipid bilayer?

    <p>Temperature and size of hydrocarbon tail</p> Signup and view all the answers

    How do some organisms adapt to environmental temperature fluctuations in relation to their membrane fluidity?

    <p>By adjusting the fatty acid content of their membranes.</p> Signup and view all the answers

    What facilitates the movement of phospholipids across the lipid bilayer?

    <p>Flippases, floppases, and scramblases.</p> Signup and view all the answers

    Which phase represents a more rigid state in the lipid bilayer?

    <p>Paracrystalline state</p> Signup and view all the answers

    Why is it important for the fluidity of a lipid bilayer to be precisely regulated?

    <p>To maintain optimal membrane function.</p> Signup and view all the answers

    What is the primary role of fibronectin in the body?

    <p>Facilitates cell adhesion and motility</p> Signup and view all the answers

    Which cell membrane protein family mediates cellular signals and facilitates cell adhesion?

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

    What is the main function of laminin in the ECM?

    <p>Organizes the sheet structure of the basal lamina</p> Signup and view all the answers

    How do integrins contribute to cell function?

    <p>Link cytoskeleton filaments with the ECM</p> Signup and view all the answers

    Which statement best describes the composition of the basal lamina?

    <p>Contains three long polypeptide chains held together by disulfide bonds</p> Signup and view all the answers

    What is the function of the basal lamina in epithelial tissues?

    <p>Forms an essential component of all epithelia</p> Signup and view all the answers

    What happens to the lipid bilayer structure of cell membranes at lower temperatures?

    <p>It stabilizes and becomes more rigid</p> Signup and view all the answers

    How do unsaturated fatty acids affect the melting point of a lipid bilayer?

    <p>Decrease the melting point</p> Signup and view all the answers

    What contributes to the fluidity of cell membranes at lower temperatures?

    <p>Shorter hydrocarbon chains in phospholipids</p> Signup and view all the answers

    How does cholesterol affect the fluidity of cell membranes at high temperatures?

    <p>Stiffens the bilayer</p> Signup and view all the answers

    What is the main role of unsaturated fatty acids in the structure of cell membranes?

    <p>Inhibit paracrystalline conformation</p> Signup and view all the answers

    What is the function of cholesterol in stabilizing cell membranes?

    <p>Supports hydrocarbon chains and stiffens the bilayer</p> Signup and view all the answers

    How do saturated fatty acids impact the phase transition temperature of a lipid bilayer?

    <p>Increase phase transition temperature</p> Signup and view all the answers

    In what way do unsaturated fatty acids differ from saturated fatty acids in influencing membrane fluidity?

    <p>Decrease melting point</p> Signup and view all the answers

    What is the effect of shorter hydrocarbon chains in membrane phospholipids on membrane fluidity?

    <p>Reduce tendency to interact at lower temperatures</p> Signup and view all the answers

    Which statement accurately describes the role of cholesterol in cell membranes at low temperatures?

    <p>Prevents fatty acid tails from interacting and clumping</p> Signup and view all the answers

    What is the primary function of elastin in tissues?

    <p>Providing elasticity for tissues</p> Signup and view all the answers

    Which amino acids are prominent in collagen proteins?

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

    What distinguishes elastin from collagen in terms of glycosylation?

    <p>Elastin is not glycosylated while collagen is</p> Signup and view all the answers

    Which type of proteins have specific binding sites for other ECM macromolecules and cell surface receptors?

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

    What is the role of laminin in the ECM?

    <p>Facilitating cell migration and adhesion</p> Signup and view all the answers

    Which protein forms glycosylated fibrils in the extracellular matrix?

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

    What proteins facilitate the trans-bilayer movement of lipids in the cell membrane?

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

    Which factor influences the movement of phospholipids within the lipid bilayer?

    <p>Temperature and size of hydrocarbon tail</p> Signup and view all the answers

    What is the primary determinant of the fluidity of a lipid bilayer?

    <p>Composition of the lipids</p> Signup and view all the answers

    Which process happens rarely in the movement of phospholipids within the bilayer?

    <p>Flip-flop</p> Signup and view all the answers

    What regulates the fluidity of a lipid bilayer based on environmental temperature fluctuations?

    <p>Adjusting fatty acid content</p> Signup and view all the answers

    Which type of protein catalyzes the movement of phospholipids and other lipids within the cell membrane?

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

    What determines the structure and flexibility of the lipid bilayer in biological membranes?

    <p>Lipid composition</p> Signup and view all the answers

    How do temperature changes affect the structure of the lipid bilayer?

    <p>Increase fluidity</p> Signup and view all the answers

    What is the role of phospholipids in the movement within the lipid bilayer?

    <p>Allow free diffusion</p> Signup and view all the answers

    Why is cholesterol considered a 'fluidity buffer' in cell membranes?

    <p>To maintain optimal fluidity levels</p> Signup and view all the answers

    What facilitates the change in shape of lipids without losing integrity in the membrane?

    <p>Noncovalent interactions</p> Signup and view all the answers

    Which factor influences the flow ability of lipid bilayers in biological membranes?

    <p>Lipid composition</p> Signup and view all the answers

    What is the main composition of Ground Substance in the extracellular matrix?

    <p>Polysaccharides and proteoglycans</p> Signup and view all the answers

    Where is protein glycosylation observed in the ECM macromolecules?

    <p>Neither collagen nor elastin</p> Signup and view all the answers

    What is the primary difference between collagen and elastin in the ECM related to glycosylation?

    <p>Elastin is glycosylated while collagen is not</p> Signup and view all the answers

    Which macromolecule provides elasticity to tissues like skin and blood vessels in the ECM?

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

    'Elastin can stretch and recoil like a rubber band due to its structure' - Which amino acids are prominent in elastin's structure?

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

    'Collagen forms stiff triple-stranded helical fibrils' - What structural characteristic of collagen makes it different from elastin?

    <p>Triple-stranded helical form</p> Signup and view all the answers

    What is the primary role of fibronectin in biological processes?

    <p>Regulation of cellular attachment and motility</p> Signup and view all the answers

    Which component is the primary organizer of the sheet structure of the basal lamina?

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

    How do integrins contribute to cell function?

    <p>Link cytoskeleton filaments with the ECM</p> Signup and view all the answers

    Which feature best describes the composition of integrins?

    <p>Hydrophobic multidomain proteins</p> Signup and view all the answers

    What is the primary function of the basal lamina in tissues?

    <p>Providing elasticity and flexibility to tissues</p> Signup and view all the answers

    Which statement accurately describes the structure of the ECM macromolecule, Laminin?

    <p>Asymmetric molecule composed of long polypeptide chains</p> Signup and view all the answers

    What effect does an increase in unsaturated fatty acids content have on the phase transition temperature of the membrane?

    <p>Decreases the phase transition temperature</p> Signup and view all the answers

    What is the role of cholesterol in cell membranes at high temperatures?

    <p>Stiffens the membrane and reduces permeability</p> Signup and view all the answers

    How do saturated fatty acids influence the melting point of a lipid bilayer?

    <p>Increase the melting point</p> Signup and view all the answers

    What is the primary function of fibroblasts in connective tissue ECM?

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

    How does an increase in cholesterol content affect membrane fluidity at high temperatures?

    <p>Decreases fluidity by stabilizing the bilayer</p> Signup and view all the answers

    What is the impact of shorter hydrocarbon chains in membrane phospholipids on the membrane's behavior at lower temperatures?

    <p>Promotes lipid movement</p> Signup and view all the answers

    How do unsaturated fatty acids affect the interaction between hydrocarbon chains within the membrane?

    <p>Increase space between chains by making packing difficult</p> Signup and view all the answers

    What is the effect of cis-double bonds in unsaturated fatty acids on membrane structure?

    <p>Inhibits paracrystalline conformation and promotes fluidity</p> Signup and view all the answers

    What is the main function of cholesterol in lowering the phase transition temperature of a membrane?

    <p>Prevents lipid clumping and enhances rigidity</p> Signup and view all the answers

    How do shorter hydrocarbon chains contribute to membrane fluidity at lower temperatures?

    <p>Reduce interactions between hydrocarbon tails, maintaining fluidity</p> Signup and view all the answers

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