Cytoskeleton Flashcards
The position of the nucleus and shape of the cell is determined by the
Cytoskeleton
The cytoskeleton is (2)
-a network of fibres (actin, tubulin, or intermediate)
-the cell’s internal skeleton
Animal cells lack a ___, so the ___ helps maintain shape
Cell wall; Cytoskeleton
Four main functions of Cytoskeleton
-structure and support
-Intracellular transport
-contractility and motility
-spatial organization
Cilia, flagella, and pseudopodia can all be used for
Cell motility
Three types of fibres that make up the cytoskeleton
-Actin (microfilaments)
-Tubulin (microtubules)
-Intermediate Filaments
Actin (6)
-most abundant Intracellular protein
-organized into rods called microfilaments
-dispersed throughout cytoplasm
-forms a dense mesh work immediately beneath plasma membrane
-determines and maintains cell’s shape
-provides mechanical strength
Along with Myosin, Actin Filaments form contractile structures such as (3)
-sarcomeres (muscle cells)
-cleavage furrow of dividing cells
-pseudopodia (allows cell to “move”)
Bundles of actin microfilaments make up the core of
Microvilli
Tubulin is organized into
Microtubules
Two protein subunits of Tubulin are
-alpha-tubulin
-beta-tubulin
Tubulin (3)
-distributed throughout the cytoplasm
-maintains cell shape (resist compression)
-tracks which organelles move
Tubulin forms ___ which are located ___
Centrioles; centrosome
Centrioles (4)
-are formed from Tubulin
-located within centrosomes
-9 sets of microtubules triplets
-involved in mitosis (cell division)
During mitosis (3)
-centrioles move to opposite ends of the cell
-microtubules extend from one centriole to the other (Spindle)
-daughter chromosomes are pulled towards each centriole
Microtubules are also present in
Cilia and Flagella
What is the only flagellated animal cell
Sperm!
Cilia occur in
Large numbers on the epithelial surface
Intermediate Filaments (5)
-fibrous proteins that are coiled to form thick cables
-distributed throughout the cell
-maintain cell shape
-tension-bearing
-anchored to cell membrane
Five major classes of Intermediate Filaments and an example
- Keratin (skin epithelial cells)
- Vimentin (epithelial cells, neural cells)
- Desmin (muscle cells)
- Glial Filaments (glial cells ie support cell in CNS)
- Neurofilaments (neurons)
Nuclear position of intermediate filaments is
Enclosed within a cage of intermediate filaments
Keratins, Vimentin, Desmin, Glial Filaments, and Neurofilaments are all
Intermediate Filaments of the Cytoskeleton
