Cytoskeletal Filament Systems

They serve as tracks for the transport of organelles and vesicles within the cell.

Motor proteins, like kinesin and dynein, walk along microtubules by undergoing conformational changes driven by ATP binding and hydrolysis.

Dyneins typically walk towards the minus end of microtubules, while kinesins mostly walk towards the plus end.

<p>The walking mechanism is driven by ATP binding, hydrolysis, and the subsequent dissociation of myosin heads from actin.</p> Signup and view all the answers

<p>Intermediate filaments are symmetric, which prevents directed movement and transport by motor proteins.</p> Signup and view all the answers

<p>The directional movement of motor proteins ensures that cellular components are delivered to the correct locations.</p> Signup and view all the answers

<p>Kinesins generally transport cargo towards the plus ends of microtubules, while dyneins transport cargo towards the minus ends.</p> Signup and view all the answers

<p>The binding and hydrolysis of ATP lead to conformational changes in the head domains of the motors, allowing them to step along the filaments.</p> Signup and view all the answers

<p>Actin filaments and microtubules serve as tracks for motor proteins to transport vesicles within the cell.</p> Signup and view all the answers

<p>Bipolar myosin II filaments slide actin filaments, which shortens the sarcomere, resulting in muscle contraction.</p> Signup and view all the answers

<p>The assay shows how motors attached to a slide can push filaments around when activated by ATP.</p> Signup and view all the answers

<p>In this sliding mechanism, the motor remains stationary while walking on the filament, causing the filament to move instead.</p> Signup and view all the answers

<p>Filament polarity allows motor proteins to travel in specific directions, ensuring orderly transport of materials.</p> Signup and view all the answers

<p>Myosin II functions by walking along actin filaments using its heads while its coiled coil tail allows assembly into bipolar structures.</p> Signup and view all the answers

<p>The motor's movement towards the positive end pushes the minus end of the filament forward, leading to sliding.</p> Signup and view all the answers

<p>Muscle contraction is driven by myosin heads walking to the plus ends of actin filaments, enabling shortening of the muscle fiber.</p> Signup and view all the answers

<p>Actin filaments maintain cell shape and enable cellular movement by forming a dynamic cytoskeletal network.</p> Signup and view all the answers

<p>Actin filaments can add and remove subunits from their ends.</p> Signup and view all the answers

<p>Microtubules are made up of heterodimers formed from alpha-tubulin and beta-tubulin.</p> Signup and view all the answers

<p>Lateral interactions between the protofilaments form the tubular structure.</p> Signup and view all the answers

<p>Actin filaments are two-stranded helices, while microtubules are hollow cylinders.</p> Signup and view all the answers

<p>Polarity allows for directional growth and function, crucial for processes like cellular transport.</p> Signup and view all the answers

<p>Nuclear lamins provide structural support and strength to the nuclear membrane.</p> Signup and view all the answers

<p>Motor proteins transport cellular cargo along microtubules, utilizing their polarity for directional movement.</p> Signup and view all the answers

<p>Intermediate filaments are composed of a diverse group of proteins, unlike the uniform structure of actin and tubulin.</p> Signup and view all the answers

<p>Their dynamic properties enable rapid remodeling, which is essential for processes like cell migration and division.</p> Signup and view all the answers

<p>Actin filament subunits interact differently as they are assembled into helical structures, while microtubule subunits form through dimerization.</p> Signup and view all the answers

<p>The 'plus' end signifies faster growth while the 'minus' end indicates slower growth, allowing for directional assembly and disassembly during cellular processes.</p> Signup and view all the answers

<p>The experiment shows that the addition of actin occurs more rapidly at the 'plus' end, indicating that this end is structurally and functionally distinct from the 'minus' end.</p> Signup and view all the answers

<p>Like actin filaments, microtubules possess a 'plus' end that grows faster and a 'minus' end that grows slower, which is essential for their dynamic roles in the cell.</p> Signup and view all the answers

<p>Filament polarity allows motor proteins to 'walk' unidirectionally along filaments, ensuring efficient transport of cellular materials towards specific destinations.</p> Signup and view all the answers

<p>The dynamic instability is influenced by the rapid growth at the 'plus' end and the slow disassembly at the 'minus' end, enabling cells to quickly adapt to changes in their environment.</p> Signup and view all the answers

<p>Intermediate filaments are primarily composed of fibrous proteins that form dimers, which then stack into antiparallel tetramers.</p> Signup and view all the answers

<p>Actin filaments enable cellular movement by polymerizing and depolymerizing, facilitating the reorganization of the cytoskeleton.</p> Signup and view all the answers

<p>Microtubules have distinct plus and minus ends, which are important for the directional transport of organelles and vesicles within cells.</p> Signup and view all the answers

<p>Motor proteins interact with filaments to generate movement and transport cellular components by converting chemical energy into mechanical work.</p> Signup and view all the answers

<p>The organization of actin filaments provides structural support and shape to the cell, enabling processes like cell division and motility.</p> Signup and view all the answers

<p>The types of intermediate filaments vary by cell type, reflecting the specific mechanical and structural needs of different tissues.</p> Signup and view all the answers

<p>The high tensile strength of intermediate filaments is due to strong lateral interactions between packed tetramers.</p> Signup and view all the answers

<p>Keratin filaments in epithelial cells distribute stress and provide structural support by anchoring to the plasma membrane.</p> Signup and view all the answers

<p>Epidermis bullosa simplex is associated with keratin mutations, leading to fragile skin that easily ruptures.</p> Signup and view all the answers

<p>Desmosomes link intermediate filaments of adjacent cells, providing mechanical strength and structural support.</p> Signup and view all the answers

<p>Nuclear lamins provide structural support and strengthen the nuclear membrane, maintaining its shape.</p> Signup and view all the answers

<p>'Plus' end grows faster and is dynamic, while 'minus' end grows more slowly and is more stable.</p> Signup and view all the answers

<p>Actin monomers assemble into a two-stranded helix, forming actin filaments.</p> Signup and view all the answers

<p>Actin polymerizes more rapidly at the 'plus' end of the seed, leading to longer filament growth.</p> Signup and view all the answers

<p>Microtubules are formed by dimers of α-tubulin and β-tubulin, which assemble into linear protofilaments.</p> Signup and view all the answers

<p>All three types of cytoskeletal filaments possess varying degrees of polarity, influencing their dynamics and function.</p> Signup and view all the answers

<p>Microtubules also have a 'plus' end that grows faster and a 'minus' end that grows slower, indicating polarity.</p> Signup and view all the answers

<p>Intermediate filaments are fibrous and more stable compared to the dynamic and tubular structures of microtubules and actin filaments.</p> Signup and view all the answers

<p>Filament polarity enables directional transport and organization of cellular components, enhancing efficiency.</p> Signup and view all the answers

<p>Motor proteins move unidirectionally along polarized filaments, allowing efficient cargo transport towards specific cellular regions.</p> Signup and view all the answers

<p>Intermediate filaments provide tensile strength to cells, preventing mechanical deformation and contributing to overall cell stability.</p> Signup and view all the answers

<p>Dynamic instability allows microtubules to rapidly grow and shrink, adapting to cellular needs during processes like mitosis.</p> Signup and view all the answers

<p>The label helps visualize and stabilize the newly added actin subunits, aiding in the study of filament dynamics.</p> Signup and view all the answers

<p>Progeria is a premature aging disease caused by defects in a specific nuclear lamin protein, leading to abnormal nuclear shape.</p> Signup and view all the answers

<p>Both exhibit faster growth at the 'plus' end, but the specific mechanisms and regulation of dynamics may vary.</p> Signup and view all the answers

<p>The slower growing 'minus' end provides stability to the filament, allowing it to maintain its structure within the cell.</p> Signup and view all the answers

<p>The seed serves as a foundation for polymerization, allowing researchers to observe how new subunits are added and how polarity affects growth.</p> Signup and view all the answers

<p>Filament polarity directs the organization and movement of cellular components, influencing processes such as division and transport.</p> Signup and view all the answers

<p>Bipolar myosin II filaments slide actin filaments by having heads that walk towards the plus ends, facilitating contraction by shortening the sarcomere.</p> Signup and view all the answers

<p>The gliding filament assay demonstrates this by activating motors on a slide, allowing them to walk on filaments and push them around.</p> Signup and view all the answers

<p>When a motor walks towards the plus end, it pushes the minus end of the filament forward, causing it to slide.</p> Signup and view all the answers

<p>Myosin II is a dimer with heads that walk on actin and a coiled coil tail, allowing multiple motors to assemble into bipolar filaments for effective contractile force.</p> Signup and view all the answers

<p>Filament polarity, with distinct plus and minus ends, allows motor proteins to travel in a specific direction, ensuring efficient cargo transport within the cell.</p> Signup and view all the answers

<p>Motor proteins walk along microtubules and actin filaments, which serve as tracks, enabling directed transport.</p> Signup and view all the answers

<p>The head domain binds to the filament, while the tail domain links to the cargo being transported.</p> Signup and view all the answers

<p>ATP binding and hydrolysis provide the energy necessary for the walking mechanism of motor proteins.</p> Signup and view all the answers

<p>Dynein walks towards the minus ends of microtubules, while kinesins typically walk towards the plus ends.</p> Signup and view all the answers

<p>Most myosins walk towards the plus ends of actin filaments, performing various cellular functions.</p> Signup and view all the answers

<p>Intermediate filaments are symmetric and lack polarity, preventing directional transport by motor proteins.</p> Signup and view all the answers

<p>The plus end demonstrates faster growth and is associated with addition of ATP-actin, while the minus end is where depolymerization occurs.</p> Signup and view all the answers

<p>Conformational changes lead to the binding, hydrolysis, and dissociation of ATP, allowing myosin to walk along actin.</p> Signup and view all the answers

<p>The asymmetrical structure of the $𝛼$-tubulin and $β$-tubulin results in distinct plus and minus ends, influencing polymerization dynamics.</p> Signup and view all the answers

<p>Motor proteins travel along cytoskeletal tracks to transport organelles and vesicles to specific locations.</p> Signup and view all the answers

<p>ATP hydrolysis triggers conformational changes in motor proteins, enabling them to 'walk' along cytoskeletal filaments.</p> Signup and view all the answers

<p>Intermediate filaments are made of symmetric subunits, which leads to non-polarity, thereby providing structural support rather than dynamic instability.</p> Signup and view all the answers

<p>Many motor proteins are dimers, possessing two heads that facilitate their movement along filament tracks.</p> Signup and view all the answers

<p>Motor proteins move directionally along polarized filaments, with plus ends facilitating forward transport and minus ends potentially hindering it.</p> Signup and view all the answers

<p>Actin filaments are involved in muscle contraction and cell shape changes, while microtubules provide tracks for motor proteins in intracellular transport.</p> Signup and view all the answers

<p>The polarity allows for rapid addition of tubulin dimers at the plus end, while the minus end can rapidly lose dimers, leading to dynamic instability.</p> Signup and view all the answers

<p>Asymmetric actin subunits create a structural polarity necessary for filament treadmilling and interaction with motor proteins.</p> Signup and view all the answers

<p>Motor proteins are adapted to bind specifically to the ends of these polarized filaments to ensure effective transport and force generation.</p> Signup and view all the answers

<p>Polarized filaments enable directional growth and movement, which is fundamental for processes like cell motility and division.</p> Signup and view all the answers

<p>Actin provides shape and drives motility due to its dynamic characteristics, while microtubules form stable scaffolding essential for organelle positioning.</p> Signup and view all the answers