1.  Network of protein fibers extending throughout the cytoplasm  Function in providing for both structural support and cell motility  Require interaction of the cytoskeleton with motor proteins  Three main kinds of fibers make up the cytoskeleton:

4.  Hollow rods  Composed of globular proteins called tubulins  Functions:  Cellular support  Tracks for organelle movement  Separation of chromosomes during cell division  Involved in the motility of the cell

7.  Centrosome – region located near the nucleus  Centriole – pair of cylindrical structures located in the centrosome of animal cells  Composed of nine sets of triplet microtubules arranged in a ring  May organize microtubule assembly during cell division

9.  Locomotor organelles formed from a specialized arrangement of microtubules  Unicellular eukaryotic organisms are propelled through water by cilia or flagella  Motile sperm cells (animals, algae, some plants) are flagellated  May function to draw fluid across the surface of stationary cells (ciliated cells lining trachea)

15.  Solid rods  Composed mainly of proteins called actin  Function:  Helps supports the cell’s shape  Participate in muscle contraction  Responsible for localized contraction of cells (dividing animal cell)

16.  Elongation and contraction of pseudopodia during amoeboid movement  Involved in cytoplasmic streaming found in plant cells  Cytoplasmic streaming (cyclosis) – flowing of the entire cytoplasm around the space between the vacuole and plasma membrane in a plant cell

19.  More permanent than microtubules or microfilaments  Constructed from keratin subunits  Function:  Specialized for bearing tension  Reinforce cell shape  Fix organelle position