Cytoskeleton

Cytoskeletal Elements

1. Actin filaments 2. Intermediate filaments 3. Microtubules

Head Region

2 globular pieces, binds to microtubule. Part of kinesin structure. Acts like feet and attaches and releases when bound by ATP on microtubules. Like delivery truck carrying transport vesicles along tracks.

Actin-Myosin Interaction

Actin filaments involved in movement by interacting with motor protein myosin. Causes cell movements.

Tail Region

Binds vesicle. Part of kinesin structure.

Cilia

Closely related to eukaryotic flagella. Short, filament-like projects. Cells have many.

Centrioles

Bundles of microtubules. Centrosomes contain 2. Oriented at 90 degrees to each other.

Cytoskeleton

Complex network of fibers. Composed of protein fibers, gives the cell shape and structural stability, aids cell movement and transport of materials within the cell, organizes all of the organelles and other cellular structures into a cohesive whole. Like transportation highway.

Kinesin Motor Protein

Converts energy in ATP into mechanical work (movement). Head and tail regions. Required for vesicle transport to occur. Moves vesicles long microtubules. Different types of molecules depending on which vesicles to carry.

Dynamic

Cytoskeleton able to alter cell's shape, transport materials in the cell, move cell itself.

Intermediate Filaments

Defined by size, not composition. Many types, each consisting of a different protein. Provides structural support for the cell. Not involved in movement, no myosin interaction, no polarity. Keratin (20 types in skin), vimentin, lamin, etc. Fivers wound into thicker cables. Maintains cell shape by resisting tension (pull). Anchors nucleus and other organelles.

Microtubules

Large, hollow tubes made of tubulin dimers (2-part compounds). Have polarity, are dynamic, and usually grow at their plus ends. Provides stability, involved in movement, provides structural framework for organelles and track for intracellular transport. Originate from the microtubule organizing center and grows outward, radiating throughout cell. Like "railroad tracks".

Flagella

Long, hairlike projections from cell surface that move cells. Cells have one of two.

Bacterial Flagella

Made of flagellum and rotates like a propeller.

Eukaryotic Flagella

Made of microtubules and wave back and forth.

Nuclear Lamins

Makes up fibrous layer supporting the double nuclear envelope, gives nucleus shape. Anchors chromosomes, helps break up and reassemble nuclear envelope.

Actin Filaments

Microfilaments, smallest cytoskeletal elements. Strands in double helix. Maintains cell shape by resisting tension (pull), moves cells via muscle contraction/cell crawling, divides animal cells in two, moves organelles and cytoplasm in plants, fungi, and animals. Form by polymerization of individual actin molecules into long bundles or dense networks. Found inside of plasma membrane and helps define cell shape.

Centrosome

Microtubule organizing center in cell. Contains 2 centrioles.

Cell Division

Microtubules move chromosomes from original cell to each resulting cell.

Taxol

Mitotic inhibitor used in cancer chemotherapy. Stabilizes microtubules which interferes with the normal breakdown of microtubules during cell division.

Transport Vesicles

Moves through cell along microtubule tracks in an energy-dependent process (requires ATP and kinesin).

Membrane Organelles

Transported and positioned by MTs and motor proteins. Important in polarized cells (secretory or epithelial cells).

Cytokinesis

Type of cell movement from actin-myosin interactions. Cell division, pinches membrane into two.

Cytoplasmic Streaming

Type of cell movement from actin-myosin interactions. Moves cytoplasm around the cell.

Cell Crawling

Type of cell movement from actin-myosin interactions. Pushes cytoplasm forward. Actin polymerization creates pseudopodia that extend and move the cell.