Cell Shape and Mobility the Cytoskeleton

Cytoskeleton• Defines cell’s shape

• Facilitates shape changes

• Enables cell movement

• Directs organelle movement

The Three Main Subunits

Microtubules

• Structure– Protein subunits

• Function– Maintains cell shape– Moves chromosomes during cell division– Moves cells about– flagella and cilia

Microtubules – maintain cell shape

Microtubules – moving chromosomes

Microtubules – moving cells with flagella and cilia

Microfilaments

• Composition– Actin – protein double strand

• Function– Maintain Shape– Motion - pseudopodia / cytoplasmic streaming– Contraction – cleavage furrow / muscle

Microfilaments – maintain shape

Microfilaments - motion– Motion - pseudopodia / cytoplasmic streaming

Microfilaments - contraction

Cytokinesis muscle contraction

Intermediate Filaments

• Composition– Keratins – a family of proteins

• Function– Reinforce cell shape