cytoskeleton Flashcards
What are the three main components of the cytoskeleton?
Microtubules, microfilaments, and intermediate filaments
What is the primary building block of microtubules?
tubular dimers
What is the primary building block of actin filaments?
Globular actin (G-actin)
How are microtubules assembled?
They assemble from tubulin dimers into protofilaments that form a hollow tube, with assembly primarily at the plus end.
How are actin filaments assembled?
They assemble from G-actin monomers into a twisted double helix structure, with growth mainly at the barbed (plus) end.
How are intermediate filaments assembled?
They form from staggered tetramer units that assemble into rope-like filaments, providing structural support
What regulates the assembly of microtubules?
Microtubule-associated proteins (MAPs) and GTP binding/hydrolysis.
What regulates the assembly of actin filaments?
actin binding proteins and ATP binding/hydrolysis
What regulates the assembly of intermediate filaments?
phosphorylation state and specific binding proteins
What are the similarities among the three cytoskeleton components?
structural support
ability to move and be stable
How do the cytoskeleton components differ in structure?
microtubules = hollow tubes
actin filaments = double helix
intermediate filament = rope like structure
Which cytoskeleton component has the highest tensile strength?
intermediate filament
What role do microtubules play in cells?
They provide structural support, form tracks for intracellular transport, and are essential for cell division by forming the mitotic spindle.
What role do actin filaments play in cells?
They support cell shape, enable cell movement, and are involved in muscle contraction, cell division, and intracellular transport.
What role do intermediate filaments play in cells?
They provide tensile strength, maintain cell shape, and anchor organelles, helping cells withstand mechanical stress
How do microtubules contribute to tissue structure?
They help organize cells within tissues and facilitate communication between cells via intracellular transport pathways
How do actin filaments contribute to tissue structure?
They support the cell cortex, aiding in cell adhesion and migration, which is critical for wound healing and tissue formation
What are non-cellular components of tissues?
The extracellular matrix (ECM), which includes proteins like collagen, elastin, and fibronectin, as well as polysaccharides and signaling molecules.
What is the extracellular matrix (ECM)?
A network of proteins and polysaccharides outside cells that provides structural support and regulates cell behavior in tissues.
How do cells interact with the extracellular matrix?
Through integrins and other cell surface receptors, allowing them to attach, sense, and respond to ECM signals.
What role does collagen play in tissues?
Collagen provides tensile strength and structural integrity in connective tissues like skin, tendons, and bones.
What role does elastin play in tissues?
Elastin gives tissues elasticity, allowing them to stretch and recoil, which is crucial for skin, lungs, and blood vessels.
How do cells assemble into tissues?
cells adhere to each other
What are cell junctions?
Structures that connect cells to each other, including tight junctions, gap junctions, and desmosomes, which help maintain tissue integrity
How do tight junctions function in tissues?
They seal neighboring cells together to prevent leakage of molecules between cells, crucial for barrier tissues like the skin and intestines.
How do gap junctions function in tissues?
They allow direct communication between adjacent cells by enabling the passage of ions and small molecules.
How do cells attach to the extracellular matrix (ECM)?
through cell surface receptors like integrins that bind to ECM proteins such as collagen, fibronectin, and laminin.
What are integrins?
Transmembrane receptors that connect the ECM to the cytoskeleton and mediate cell-ECM adhesion and signaling.
How does integrin binding to the ECM affect cell behavior?
It triggers signaling pathways that influence cell survival, proliferation, migration, and differentiation
What is focal adhesion?
A complex of integrins and intracellular proteins that anchors cells to the ECM and transmits signals to the cell interior
How does ECM stiffness affect cell signaling?
Stiffer ECMs can enhance integrin activation, promoting signaling pathways linked to cell growth and differentiation, important in tissues like bone
How does ECM composition influence cell signaling?
different ECM proteins bind to specific integrins leading to varied signals
What role does ECM remodeling play in signaling?
ECM remodeling alters cell attachment sites and can activate integrins, modifying signaling pathways and cellular responses
How do integrins activate intracellular signaling pathways?
By clustering and recruiting signaling proteins at focal adhesions, activating pathways like MAPK, PI3K/Akt, and Rho GTPases
What is the role of Rho GTPases in ECM signaling?
Rho GTPases regulate actin cytoskeleton dynamics in response to ECM attachment, influencing cell shape, movement, and tension
How does cell detachment from the ECM affect signaling?
can trigger apoptosis
What is mechanotransduction in the context of cell-ECM interaction?
The process by which cells sense mechanical properties of the ECM through integrins, converting these signals into biochemical responses.
How do focal adhesions contribute to mechanotransduction?
They sense ECM stiffness and transmit mechanical forces to the cell, influencing cytoskeletal tension and signaling pathways
