96 Questions
What type of filaments are made up of smaller subunits that form helical assemblies through self-association?
Microfilaments
Which protein accelerates depolymerization of actin filaments?
Cofilin
What is the primary function of actin in cells?
Mechanical support
Which crosslinking protein forms linear bundles of actin filaments?
Fascin
What does ATP binding do to actin monomers in filaments?
Enhances stability and affinity for neighboring subunits
Which protein regulates actin dynamics by inhibiting nucleation?
Profilin
What is the main function of the sarcoplasmic reticulum in muscle cells?
Storing Calcium Ions
What does the binding of Ca²⁺ to TnC in the tropomyosin-troponin complex allow?
Facilitates the binding of myosin to actin filaments
Which proteins are associated with actin filaments in striated muscles?
Tropomyosin, Troponin C, Troponin T
What triggers an action potential in muscle cells?
Depolarization of myofibrils
What is the role of myosin heads in muscle contraction according to the Sliding Filament Model?
Interacting with actin filaments to create tension
What blocks the binding of myosin to actin filaments in muscle cells?
Troponin-tropomyosin complex
What is the main function of the cytoskeleton in a cell?
Maintaining correct shape and structure
Which type of filaments determines the positions of membrane-enclosed organelles in a cell?
Microtubules
What is the diameter of microtubules in the cytoskeleton?
24 nm
Which type of filaments provides mechanical strength to a cell?
Intermediate filaments
What is the function of actin filaments in a cell?
Determining cell shape and necessary for cell locomotion
How are actin filaments and microtubules structured?
Compact and globular
What is the main function of the cytoskeleton in a cell?
Determining cellular organization and polarity
Which structure is described as a cellular membrane protrusion that increases surface area?
Microvilli
Why do cells need proper organization in space according to the text?
To interact with each other
What is the function of Adherens Junctions in a cell?
Occurring at cell-cell junctions
Which statement best describes the role of the cytoskeleton filaments in forming polarized structures?
It allows rapid modification of cell structure under different conditions
What is the significance of Apical and Basolateral Membranes in a cell?
Defining directional orientation within the cell
Which part of the cell is responsible for pushing out protrusions at its front or leading edge?
Actin
During cytokinesis in eukaryotic cell division, what structure divides the cell in two?
Contractile ring of actin and myosin
Which motor protein is responsible for muscle contraction in most animal cells?
Myosin I
Which cells are known for their ability to crawl by pushing out protrusions and dragging themselves forward by traction?
Amoeba and Fibroblasts
Which type of cells actively divide using a contractile ring consisting of actin and myosin after mitosis?
Fibroblasts
What type of motion do actin-dependent motor proteins generate inside cells?
Linear motion
What causes the cell to move forward by traction?
Actin filaments
Which motor protein family do all actin-dependent motor proteins belong to?
Myosin family
What is the main function of a contractile ring during cytokinesis in eukaryotic cell division?
Divides the cell in two
Which cells are examples of those that can push out protrusions and move forward by traction?
Amoeba
What type of motion do actin-dependent motor proteins generate inside cells?
Powered motion
Which statement best describes the role of the contractile ring during cytokinesis?
Divides the cytoplasm into two daughter cells
Which type of filaments are necessary for cell locomotion?
Actin filaments
What function do microtubules serve in a cell?
Determining organelle positions
What is the diameter of intermediate filaments in the cytoskeleton?
8-12 nm
What is the role of actin filaments in shaping a cell?
Providing mechanical strength
Which component of the cytoskeleton is responsible for directing intracellular transport?
Microtubules
What aspect of a cell does actin filaments specifically determine?
Cell shape
What triggers muscle contraction by moving the tropomyosin-troponin complex and freeing the myosin-binding site on actin filaments?
Depolarization of myofibrils by calcium ions
Which protein attaches to actin filaments and uses ATP hydrolysis to generate motor force in muscle cells?
Myosin
In muscle cells, what causes the thin actin filament to slide over the thick myosin filament during contraction?
Interaction of myosin heads with actin filaments
Which event leads to the simultaneous shortening of all sarcomeres in muscle cells?
Myosin head walking along actin filaments
What is the role of tropomyosin in muscle cells regarding the binding of myosin to actin filaments?
Blocks the binding site in the presence of calcium ions
During muscle contraction, what primary function is performed by the sarcoplasmic reticulum in terms of calcium ions?
Storing and releasing calcium ions for contraction
What kind of filaments are made up of smaller subunits that form helical assemblies through self-association?
Intermediate filaments
Which protein inhibits nucleation in actin polymerization dynamics?
Profilin
What is the main function of actin in cells related to microvilli support?
Support microvilli projections
Which type of proteins form linear bundles of actin filaments?
Fascin
What process allows actin filaments to polymerize or depolymerize, enabling cell migration and interactions with the environment?
Hydrolysis
Which accessory protein accelerates the depolymerization of actin filaments?
Cofilin
What is the main consequence of no aerobic respiration in muscle cells?
Deterioration of sarcoplasmic reticulum
How does alpha-amanitin affect actin filaments?
Blocks depolymerization of actin filaments
What role do chemical compounds such as phalloidin play in studying actin filaments?
Stabilize or destabilize actin filaments
What is the toxic effect of phalloidin on cells?
Binds actin filaments selectively
What is the primary function of the cytoskeleton in a cell?
To organize and maintain cell shape and structure
Which type of filaments determine the positions of membrane-enclosed organelles and direct intracellular transport?
Microtubules
What is the role of actin filaments in a cell's functions?
Determine cell shape and enable cell movement
Which cytoskeletal component is crucial for cell locomotion?
Actin filaments
What is the diameter range of intermediate filaments in the cytoskeleton?
$5-10$ nm
Which type of filaments are necessary for stabilizing a cell's environment by associating it with surrounding tissues?
Intermediate filaments
What is the main function of microtubules within a cell?
Direct organelle positions and intracellular transport
How do actin filaments contribute to cell locomotion?
$By$ $determining$ $the$ $shape$ $of$ $the$ $cell$ $and$ $enabling$ $movement$ $and$ $migration$
What is responsible for dividing the eukaryotic cell into two daughter cells during cytokinesis?
A contractile ring consisting of actin filaments and myosin
Which motor proteins are associated with causing motion inside cells in association with parts of the cytoskeleton?
Myosin, Kinesin, and Actin
Which protein family do all actin-dependent motor proteins belong to?
Myosin family
What is the primary function of the contractile ring during cytokinesis in eukaryotic cell division?
Dividing the cell into two daughter cells
What causes motion inside cells by generating force in muscle cells?
Myosin
Which proteins form contractile structures by associating with actin to facilitate muscle contraction?
Myosin II
What type of cells are capable of pushing out protrusions and moving forward by traction?
Neutrophils (WBC)
Which part of the cell pushes out its protrusion at its front or leading edge?
Cell
What is the main function of the cytoskeleton in a cell?
Providing mechanical strength
Which structure is described as a cellular membrane protrusion that increases surface area?
Microvilli
What is the significance of Apical and Basolateral Membranes in a cell?
Maintaining cell polarity
Which protein uses ATP hydrolysis to generate motor force in muscle cells?
Myosin
What do Adherens Junctions represent within a cell?
Protein complexes at cell-cell junctions
Which event leads to the simultaneous shortening of all sarcomeres in muscle cells?
Contraction of muscle fibers
What is the primary function of actin in cells related to microvilli support?
"Increasing surface area"
What does the binding of Ca²⁺ to TnC in the tropomyosin-troponin complex allow?
"Contraction of muscle fibers"
What is the primary function of the sarcoplasmic reticulum during muscle contraction?
Releasing calcium ions for muscle contraction
In muscle cells, what causes the simultaneous shortening of all sarcomeres?
Actin filaments sliding past myosin filaments
What triggers an action potential in muscle cells to initiate muscle contraction?
Release of calcium ions from the sarcoplasmic reticulum
What happens during rigor mortis in muscles?
Freezing of sarcomeres in a contracted state
What is the role of tropomyosin in striated muscle in the absence of Ca²⁺ ions?
Preventing attachment of myosin to actin
What causes the release of myosin heads from actin filaments during muscle contraction?
Binding of Ca²⁺ ions to troponin C
What is the function of the troponin complex in muscle cells during contraction?
Interacting with Ca²⁺ ions to regulate muscle contraction
How does the binding of Ca²⁺ ions to troponin C affect muscle contraction?
"Crossbridge detachment" and relaxation of sarcomeres
Which protein accelerates depolymerization of actin filaments?
Cofilin
What is the primary function of ATP-bound actin in actin filaments?
Stabilizes the filament by having a higher affinity for neighboring subunits
Which accessory protein inhibits nucleation during actin dynamics?
Profilin
What role do bundle-forming crosslinkers play in actin filaments regarding cell shape?
Form linear bundles making the structure more rigid
What is the main function of gel-forming crosslinkers in actin filaments?
Create 3D meshwork with semisolid properties
How do actin filaments in muscle cells differ from microtubules?
Actin filaments have parallel protofilaments compared to microtubules
This quiz covers the fundamentals of the cytoskeleton, including intermediate filaments, microtubules, and actin, and their role in determining cellular organization and polarity. Learn about the importance of the cytoskeleton in providing cells with strength, shape, and the ability to move.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
