A Tour of the Cell

Components of the CytoskeletonIntermediate Filaments•Intermediate filaments range in diameter from 8–12nanometers, larger than microfilaments but smaller thanmicrotubules•They support cell shape and fix organelles in placeExtracellular components and connections between cellshelp coordinate cellular activities•Most cells synthesize and secrete materials that are external to the plasma membrane•These extracellular structures include:Cell Walls of PlantsThe cell wall is an extracellular structure thatdistinguishes plant cells from animal cells•Plant cell walls may have multiple layers:–Primary cell wall:Centralvacuoleof cellPlasmamembraneSecondarycell wallPrimarycell wall–Middle lamella:Centralvacuoleof cellMiddlelamella–Secondary cell wall (in some cells:Central vacuole1 µmCytosolPlasma membranePlant cell wallsPlants: PlasmodesmataPlasmodesmataCell wallsInteriorof cell•Through plasmodesmata, water and small solutes (andsometimes proteins and RNA) can pass from cell to cellInteriorof cellPlasmodesmataPlasma membranes