Cytoskeleton

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Cytoskeleton
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Cytoskeleton

• A cytoskeleton is a network of fibers that
  organizes structures and activities.
• Extends through cytoplasm
• Composed of three molecular structures
• Microtubules
• Microfilaments
• Intermediate Filaments

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Roles of Cytoskeleton
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Supports the cell and maintains its shape

• Stabilized by balance between opposing forces
  of its elements
• Anchors organelles and cytosolic enzyme molecules
• Easily dismantled and reassembled

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Roles Cell Motility

• Cytoskeleton interacts with motor proteins
• Cilia and flagella grip microtubules to propel
• Vesicles travel along monorails
• Cytoplasm circulates materials

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Regulation of Biochemical Activities

• Transmits mechanical forces via surface proteins

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Components of Cytoskeleton
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Microtubules

• Found in cytoplasm of eukaryotic cells
• Widest diameter
• Composed of globular protein, tubulin
• Shapes and supports the cell
• Separates chromosomes during cell division

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Centrosomes and Centrioles

• Microtubule-organizing center
• Centriole found within chromosome

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Cilia and Flagella

• Locomotor appendages
• Moves fluid over the surface of tissue
• Different beating pattern, length, and number
• Common ultrastructure

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Microfilaments (Actin Filaments)

• Composed of globular protein, actin
• Found in all eukaryotic cells
• Motor protein, myosin
• Muscle contraction
• Distribution of materials by cytoplasmic
  streaming

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Intermediate Filaments

• Named for diameter
• Bears tension
• Keratin proteins
• More permanent
• Holds shape of cell and position of organelles