The Cytoskeleton, CELL SHAPE AND MOTILITY JAN MUHAMMAD
What is Cytoskeleton? Cytoplasm contains a complex network of filaments and microtubules which form a structural framework known as CYTOSKELETON.
= Cytoskeleton: The skeleton and muscle of a cell Cells need (cyto) skeleton to: *create shape *change shape *allow movement Dynamic!
Three main kinds of fibers make up the CYTOSKELETON: ● MICROFILAMENT ● INTERMEDIATE FILAMENT ● MICROTUBULES
MICROFILAMENT ● Thinnest filament present in the cytoskeleton in cytoplasm of eukaryotic cell. ● Give the cell its shape and enable cell movement
MICROFILAMENT
FUNCTIONS OF MICROFILAMENT Microfilaments play a role in structure, cell motility, and cell division. Microfilaments are made of actin, and thus are involved in muscle contraction as well as cell division.
INTERMEDIATE FILAMENTS ● Made of variety of proteins, including keratin, desmin and vimentin ● 8 to 12 nanometer ● Composed of two anti parallel dimer
INTERMEDIATE FILAMENTS
FUNCTIONS OF INTERMEDIATE FILAMENT ● provide mechanical support for the plasma membrane where it comes into contact with other cells or with the extracellular matrix ● intermediate filaments do not participate in cell motility.
MICROTUBULES ● Microtubules, the thickest fibers, are hollow rods about 25 microns in diameter. ● Microtubule fibers are made up of the globular protein, tubulin, and they grow or shrink as more tubulin molecules are added or removed.
MICROTUBULES
FUNCTIONS OF MICROTUBULES Microtubules participate in the intracellular transport of organelles and vesicles.
Microtubules are the central structural supports in cilia and flagella Microtubules are the central structural supports in cilia and flagella. The locomotive appendages of cell
Cilia ● minute hairlike organelles, identical in structure to flagella, that line the surfaces of certain cells and beat in rhythmic waves, providing locomotion to ciliate protozoan and moving liquids along internal epithelial tissue in animals.
CILIA
FLAGELLA ● A slender threadlike structure, esp. a microscopic whiplike appendage that enables many protozoa, bacteria, spermatozoa, etc., to swim.
FLAGELLA
FLAGELLA
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