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
