100%(7)7 out of 7 people found this document helpful
This preview shows page 4 - 7 out of 10 pages.
Dyenins move toward the negative end of the cellSpecific kinesins/dyenins for each different cargooCilia and flagellaCilia contain a core of stable microtubules that grow from a basal bodyCilia allow eukaryotic cells to move fluid over their surfaceFlagella helps propel sperm/protozoa through fluid~0.25 micrometers in diameter, covered in plasma membranegenerate the axoneme (skeleton of whip-like structures)cilium beats by performing repetitive rounds of a power strokeoCiliopathiesSymptoms:Cystic KidneysPolydactylyHearing lossMale infertilityRetinal degenerationImproper organ placementRespiratory diseaseCancerActin FilamentsoActin filaments are thin and flexibleoMany proteins bind to actin and modify its propertiesoAn actin-rich cortex underlies the plasma membrane of most eukaryotic cellsoCell crawling depends on actinoActin associates with myosin to form contractile structuresoExtracellular signals control the arrangement of actin filaments allowing cell to respond to environment
o5% total protein in a typical animal cell is actino½ of actin is assembled into filaments the other ½ are actin monomers in cytosoloActin filaments allow cells to adopt a variety of shapesActin fibers like microtubules are unstableMade stable by interactions with other proteins “actin binding proteins”Differential interactions determine “stiffness” of the structureCan form stiff “microvilli” (A) or flexible “cellular muscles” (B)Can form temporary protrusions (C) or a contractile ring which pinches off (D)oActin – think flexible protein threadsPolarity – positive and negative endsThinner, shorter and more flexible than microtubulesFilaments often only persist for a few minutes after they are formed – dynamic, moving and changingoActin-binding proteins control the behavior of action filaments in vertebrate cellsFormins and actin-related proteins (ARPs) control actin assembly
oThe cortexActin rich network which lies under the cytoplasmGives cell its shapeAllows cell to moveoCell movement1) cell pushes out protrusions at its “front” or leading edge2) protrusions adhere to the surface over which the cell is crawling3) the rest of the cell drags itself forwardoCell crawling relies on actinIntegrins – transmembrane proteins which bind to the extracellular matrix