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CYTOSKELETON presentation by (Aneeq) (1).pptx

  1. CYTOSKELETON Presented by: M.Aneeq Javed Presented to: Dr Fatima Sughra 11/28/2022
  2. Content • What is cytoskeleton? • Structure of cytoskeleton • Function of cytoskeleton • Microtubules • Microfilaments • Intermediate filaments 11/28/2022
  3. What is cytoskeleton • The complex network of protein fibers that give mechanical support and strength to cell and maintain its shape(especislly in animal cell) known as Cytoskeleton. • Act as skeleton and muscle of the cell. • Also responsible for segregation of chromosomes into two daughter cell at cell division. 11/28/2022
  4. Structure of cytoskeleton In eukaryotes, the cytoskeleton is built on a framework of three types of protein filaments. •Intermediate filaments •Microtubules •Microfilaments And these are capable of rapid growth or disassembly dependent on the cell’s requirements. 11/28/2022
  5. FUNCTIONS OF CYTOSKELETON • It imparts the cell shape. • It provides protection by resistance to deformation. • It can actively contract, deforming the cell and its environment, allowing cells to migrate. • It is involved in cell signaling pathways. • It separates chromosomes during cell division. • It provides a blueprint to organize the organelles in cytoplasm and for the construction of cytoplasm. • It gives rise to structures such as flagella and cilia. 11/28/2022
  6. Microtubules • Microtubules are hollow rods functioning primarily to help support and shape the cell and as "routes" along which organelles can move. • Microtubules are typically found in all eukaryotic cells. • They vary in length and measure about 25 nm in diameter. • They are polymers of alpha and beta. tubulin. • They have a very dynamic behaviour, binding for polymerization. • They are commonly organized by the centrosome. 11/28/2022
  7. Functions of Microtubules •Intracellular transport (associated with dyneins and kinesins, they transport organelles like mitochond ria or vesicles). •The axoneme of cilia and flagella. •The mitotic spindle. •Synthesis of the cell wall in plants 11/28/2022
  8. Microfilaments •Microfilaments or actin filaments are thin, solid rods that are active in muscle contraction. •Microfilaments are particularly prevalent in muscle cells. •Microfilaments measure up to 8 nm in diameter. • Major component or protein of microfilaments are actin. •It consists of tropomyosin ,actin and troponin. •Specifically,the actin subunits that come together to form a microfilament called G-actin and once they are joined called F-actin. 11/28/2022
  9. Functions of microfilaments Functions include:Muction •Cell movement •Muscle contraction •Intracellular transport •Maintenance of cell shape •Cytokinesis •Cytoplasmic streaming or cyclosis 11/28/2022
  10. Intermediate filaments •Intermediate filaments can be abundant in many cells and provide support for microfilaments and microtubules by holding them in place. • These filaments form keratins found in epithelial cells and neurofilaments in neurons. •They measure 10 nm in diameter. •Intermediate filaments are most commonly known as the support system or “scaffolding” for the cell and nucleus while also playing a role in some cell functions. 11/28/2022
  11. Functions of intermediate filaments Different intermediate filaments are: •Made of vimentin. Vimentin intermediate filaments are in general present in mesenchymal cells. •Made of keratin. Keratin is present in general in epithelial cells. •Neurofilaments of neural cells. •Made of lamin, giving structural support to the nuclear envelope. •Made of desmin, play an important role in structural and mechanical support of muscle cells.
  12. Comparison 11/28/2022 Cytoskeleton type Diameter In nm structure Microfilaments 6 Double helix Actin Intermediate filaments 10 Two anti parallel helix,dimer, forming tetramers ∙vimentin Microtubules 23 Protofilaments,in turn of consisting tublin subunits Alpha and beta tubulin
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