Cytoskeleton 1
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Questions and Answers

What type of filaments are made up of smaller subunits that form helical assemblies through self-association?

  • Microtubules
  • Actin filaments
  • Intermediate filaments
  • Microfilaments (correct)

    • Which protein accelerates depolymerization of actin filaments?

  • Filamin
  • Cofilin (correct)
  • Profilin
  • Fascin

    • What is the primary function of actin in cells?

  • Energy production
  • Mechanical support (correct)
  • DNA replication
  • Cell division

    • Which crosslinking protein forms linear bundles of actin filaments?

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

    What does ATP binding do to actin monomers in filaments?

    <p>Enhances stability and affinity for neighboring subunits</p> Signup and view all the answers

    Which protein regulates actin dynamics by inhibiting nucleation?

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

    What is the main function of the sarcoplasmic reticulum in muscle cells?

    <p>Storing Calcium Ions</p> Signup and view all the answers

    What does the binding of Ca²⁺ to TnC in the tropomyosin-troponin complex allow?

    <p>Facilitates the binding of myosin to actin filaments</p> Signup and view all the answers

    Which proteins are associated with actin filaments in striated muscles?

    <p>Tropomyosin, Troponin C, Troponin T</p> Signup and view all the answers

    What triggers an action potential in muscle cells?

    <p>Depolarization of myofibrils</p> Signup and view all the answers

    What is the role of myosin heads in muscle contraction according to the Sliding Filament Model?

    <p>Interacting with actin filaments to create tension</p> Signup and view all the answers

    What blocks the binding of myosin to actin filaments in muscle cells?

    <p>Troponin-tropomyosin complex</p> Signup and view all the answers

    What is the main function of the cytoskeleton in a cell?

    <p>Maintaining correct shape and structure</p> Signup and view all the answers

    Which type of filaments determines the positions of membrane-enclosed organelles in a cell?

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

    What is the diameter of microtubules in the cytoskeleton?

    <p>24 nm</p> Signup and view all the answers

    Which type of filaments provides mechanical strength to a cell?

    <p>Intermediate filaments</p> Signup and view all the answers

    What is the function of actin filaments in a cell?

    <p>Determining cell shape and necessary for cell locomotion</p> Signup and view all the answers

    How are actin filaments and microtubules structured?

    <p>Compact and globular</p> Signup and view all the answers

    What is the main function of the cytoskeleton in a cell?

    <p>Determining cellular organization and polarity</p> Signup and view all the answers

    Which structure is described as a cellular membrane protrusion that increases surface area?

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

    Why do cells need proper organization in space according to the text?

    <p>To interact with each other</p> Signup and view all the answers

    What is the function of Adherens Junctions in a cell?

    <p>Occurring at cell-cell junctions</p> Signup and view all the answers

    Which statement best describes the role of the cytoskeleton filaments in forming polarized structures?

    <p>It allows rapid modification of cell structure under different conditions</p> Signup and view all the answers

    What is the significance of Apical and Basolateral Membranes in a cell?

    <p>Defining directional orientation within the cell</p> Signup and view all the answers

    Which part of the cell is responsible for pushing out protrusions at its front or leading edge?

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

    During cytokinesis in eukaryotic cell division, what structure divides the cell in two?

    <p>Contractile ring of actin and myosin</p> Signup and view all the answers

    Which motor protein is responsible for muscle contraction in most animal cells?

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

    Which cells are known for their ability to crawl by pushing out protrusions and dragging themselves forward by traction?

    <p>Amoeba and Fibroblasts</p> Signup and view all the answers

    Which type of cells actively divide using a contractile ring consisting of actin and myosin after mitosis?

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

    What type of motion do actin-dependent motor proteins generate inside cells?

    <p>Linear motion</p> Signup and view all the answers

    What causes the cell to move forward by traction?

    <p>Actin filaments</p> Signup and view all the answers

    Which motor protein family do all actin-dependent motor proteins belong to?

    <p>Myosin family</p> Signup and view all the answers

    What is the main function of a contractile ring during cytokinesis in eukaryotic cell division?

    <p>Divides the cell in two</p> Signup and view all the answers

    Which cells are examples of those that can push out protrusions and move forward by traction?

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

    What type of motion do actin-dependent motor proteins generate inside cells?

    <p>Powered motion</p> Signup and view all the answers

    Which statement best describes the role of the contractile ring during cytokinesis?

    <p>Divides the cytoplasm into two daughter cells</p> Signup and view all the answers

    Which type of filaments are necessary for cell locomotion?

    <p>Actin filaments</p> Signup and view all the answers

    What function do microtubules serve in a cell?

    <p>Determining organelle positions</p> Signup and view all the answers

    What is the diameter of intermediate filaments in the cytoskeleton?

    <p>8-12 nm</p> Signup and view all the answers

    What is the role of actin filaments in shaping a cell?

    <p>Providing mechanical strength</p> Signup and view all the answers

    Which component of the cytoskeleton is responsible for directing intracellular transport?

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

    What aspect of a cell does actin filaments specifically determine?

    <p>Cell shape</p> Signup and view all the answers

    What triggers muscle contraction by moving the tropomyosin-troponin complex and freeing the myosin-binding site on actin filaments?

    <p>Depolarization of myofibrils by calcium ions</p> Signup and view all the answers

    Which protein attaches to actin filaments and uses ATP hydrolysis to generate motor force in muscle cells?

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

    In muscle cells, what causes the thin actin filament to slide over the thick myosin filament during contraction?

    <p>Interaction of myosin heads with actin filaments</p> Signup and view all the answers

    Which event leads to the simultaneous shortening of all sarcomeres in muscle cells?

    <p>Myosin head walking along actin filaments</p> Signup and view all the answers

    What is the role of tropomyosin in muscle cells regarding the binding of myosin to actin filaments?

    <p>Blocks the binding site in the presence of calcium ions</p> Signup and view all the answers

    During muscle contraction, what primary function is performed by the sarcoplasmic reticulum in terms of calcium ions?

    <p>Storing and releasing calcium ions for contraction</p> Signup and view all the answers

    What kind of filaments are made up of smaller subunits that form helical assemblies through self-association?

    <p>Intermediate filaments</p> Signup and view all the answers

    Which protein inhibits nucleation in actin polymerization dynamics?

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

    What is the main function of actin in cells related to microvilli support?

    <p>Support microvilli projections</p> Signup and view all the answers

    Which type of proteins form linear bundles of actin filaments?

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

    What process allows actin filaments to polymerize or depolymerize, enabling cell migration and interactions with the environment?

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

    Which accessory protein accelerates the depolymerization of actin filaments?

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

    What is the main consequence of no aerobic respiration in muscle cells?

    <p>Deterioration of sarcoplasmic reticulum</p> Signup and view all the answers

    How does alpha-amanitin affect actin filaments?

    <p>Blocks depolymerization of actin filaments</p> Signup and view all the answers

    What role do chemical compounds such as phalloidin play in studying actin filaments?

    <p>Stabilize or destabilize actin filaments</p> Signup and view all the answers

    What is the toxic effect of phalloidin on cells?

    <p>Binds actin filaments selectively</p> Signup and view all the answers

    What is the primary function of the cytoskeleton in a cell?

    <p>To organize and maintain cell shape and structure</p> Signup and view all the answers

    Which type of filaments determine the positions of membrane-enclosed organelles and direct intracellular transport?

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

    What is the role of actin filaments in a cell's functions?

    <p>Determine cell shape and enable cell movement</p> Signup and view all the answers

    Which cytoskeletal component is crucial for cell locomotion?

    <p>Actin filaments</p> Signup and view all the answers

    What is the diameter range of intermediate filaments in the cytoskeleton?

    <p>$5-10$ nm</p> Signup and view all the answers

    Which type of filaments are necessary for stabilizing a cell's environment by associating it with surrounding tissues?

    <p>Intermediate filaments</p> Signup and view all the answers

    What is the main function of microtubules within a cell?

    <p>Direct organelle positions and intracellular transport</p> Signup and view all the answers

    How do actin filaments contribute to cell locomotion?

    <p>$By$ $determining$ $the$ $shape$ $of$ $the$ $cell$ $and$ $enabling$ $movement$ $and$ $migration$</p> Signup and view all the answers

    What is responsible for dividing the eukaryotic cell into two daughter cells during cytokinesis?

    <p>A contractile ring consisting of actin filaments and myosin</p> Signup and view all the answers

    Which motor proteins are associated with causing motion inside cells in association with parts of the cytoskeleton?

    <p>Myosin, Kinesin, and Actin</p> Signup and view all the answers

    Which protein family do all actin-dependent motor proteins belong to?

    <p>Myosin family</p> Signup and view all the answers

    What is the primary function of the contractile ring during cytokinesis in eukaryotic cell division?

    <p>Dividing the cell into two daughter cells</p> Signup and view all the answers

    What causes motion inside cells by generating force in muscle cells?

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

    Which proteins form contractile structures by associating with actin to facilitate muscle contraction?

    <p>Myosin II</p> Signup and view all the answers

    What type of cells are capable of pushing out protrusions and moving forward by traction?

    <p>Neutrophils (WBC)</p> Signup and view all the answers

    Which part of the cell pushes out its protrusion at its front or leading edge?

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

    What is the main function of the cytoskeleton in a cell?

    <p>Providing mechanical strength</p> Signup and view all the answers

    Which structure is described as a cellular membrane protrusion that increases surface area?

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

    What is the significance of Apical and Basolateral Membranes in a cell?

    <p>Maintaining cell polarity</p> Signup and view all the answers

    Which protein uses ATP hydrolysis to generate motor force in muscle cells?

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

    What do Adherens Junctions represent within a cell?

    <p>Protein complexes at cell-cell junctions</p> Signup and view all the answers

    Which event leads to the simultaneous shortening of all sarcomeres in muscle cells?

    <p>Contraction of muscle fibers</p> Signup and view all the answers

    What is the primary function of actin in cells related to microvilli support?

    <p>&quot;Increasing surface area&quot;</p> Signup and view all the answers

    What does the binding of Ca²⁺ to TnC in the tropomyosin-troponin complex allow?

    <p>&quot;Contraction of muscle fibers&quot;</p> Signup and view all the answers

    What is the primary function of the sarcoplasmic reticulum during muscle contraction?

    <p>Releasing calcium ions for muscle contraction</p> Signup and view all the answers

    In muscle cells, what causes the simultaneous shortening of all sarcomeres?

    <p>Actin filaments sliding past myosin filaments</p> Signup and view all the answers

    What triggers an action potential in muscle cells to initiate muscle contraction?

    <p>Release of calcium ions from the sarcoplasmic reticulum</p> Signup and view all the answers

    What happens during rigor mortis in muscles?

    <p>Freezing of sarcomeres in a contracted state</p> Signup and view all the answers

    What is the role of tropomyosin in striated muscle in the absence of Ca²⁺ ions?

    <p>Preventing attachment of myosin to actin</p> Signup and view all the answers

    What causes the release of myosin heads from actin filaments during muscle contraction?

    <p>Binding of Ca²⁺ ions to troponin C</p> Signup and view all the answers

    What is the function of the troponin complex in muscle cells during contraction?

    <p>Interacting with Ca²⁺ ions to regulate muscle contraction</p> Signup and view all the answers

    How does the binding of Ca²⁺ ions to troponin C affect muscle contraction?

    <p>&quot;Crossbridge detachment&quot; and relaxation of sarcomeres</p> Signup and view all the answers

    Which protein accelerates depolymerization of actin filaments?

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

    What is the primary function of ATP-bound actin in actin filaments?

    <p>Stabilizes the filament by having a higher affinity for neighboring subunits</p> Signup and view all the answers

    Which accessory protein inhibits nucleation during actin dynamics?

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

    What role do bundle-forming crosslinkers play in actin filaments regarding cell shape?

    <p>Form linear bundles making the structure more rigid</p> Signup and view all the answers

    What is the main function of gel-forming crosslinkers in actin filaments?

    <p>Create 3D meshwork with semisolid properties</p> Signup and view all the answers

    How do actin filaments in muscle cells differ from microtubules?

    <p>Actin filaments have parallel protofilaments compared to microtubules</p> Signup and view all the answers

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