Download Life Science

Chapter 5, Lesson 6 Notes
The Cytoskeleton
Cytoskeleton Structure
 Composed of a network of protein fibers called
microfilaments, intermediate filaments, and microtubules.
Cytoskeleton Function
1. gives cells support and helps the cell keep its shape
2. anchors organelles into a certain position or allows them to
move around in the cell
3. allows cells to move by functioning as a muscle
Types of Cytoskeleton Fibers
1. Microfilaments – made of strings of ball-shaped proteins called actin.
The actin are twisted together to make long fiber molecules. They are
mainly responsible for moving the whole cell around.
2. Intermediate filaments – made from long, string-like proteins, they
coil together like rope to form rods that add strength to the shape of
the cell.
3. Microtubules – made from units of a ball-shaped protein called
tubulin. The tubulin molecules come together to form a hollow tube
that supports the cell’s shape.
Microtubules’ Function Outside the Cell
 Outside the cell, the microtubules anchor to and extend out of the
plasma membrane.
 They form two types of structures—cilia and flagella. Both cilia and
flagella are made of microtubules.
(draw and label the picture of the eukaryotic cell on p. 155)