Cytoskeleton Proteins + Inclusions Flashcards
Define Actin
The thinnest component of cytoskeleton
-made of globular actin monomers, polymerize into a microfilament
-dynamic, + end growing
-nucleation often at plasma membrane
-subunits can dissociate from (-) end and refuse to (+) end. This is treadmilling
What are the functions of actin filaments
-Maintain cell shape
-Anchor membrane proteins
-Can provide flexible or stable support
-Aids in cell motility
Where is actin nucleation?
Often at plasma membrane
What microfilament are microvilli composed of?
Stable bundles of actin filaments anchored to a terminal wen of actin in cell cortex at base of microvilli
What protein contracts actin filaments?
Myosin
Define microtubules
Hollow, non-branching cylinders
-nucleation site at microtuble organizing center near the nucleus (centromere)
-tread milling can occur
What are the functions of microtubles
-mitotic spindle formation
-cilia and flagella
-cytostructural support
-act as “railroad tracks” for motor proteins
What microtubule structure is essential in cilia formation?
Basal body: organizing center for microtubules
What two proteins are needed for movement along microtubles?
Dyneins: movement toward nucleus
Kinesins: movement away from nucleus
Define intermediate filaments
Structural role. Stable rope-like filaments
What are the functions of intermediate filaments
-Maintain cell shape
-anchor organelles
-cell-cell junctions (gap junctions)
-cell-matrix juntions
Define inclusions and give 5 examples
They are inert and not metabolically active
-melanin
-lipofuscin
-hemosiderin
-glycogen
-lipid
