1. a network of protein fibres
2. present in the cytoplasm of all eukaryotic cell
3. microtubules
3.1. present in all eukaryotic cells
3.2. size
3.2.1. about 25nm in external diameter
3.2.2. unbranched hollow tubes
3.3. wall
3.3.1. about 5nm thick
3.3.2. made up of helically arranged of globulin proteins
3.3.2.1. tubulin
3.4. functions
3.4.1. determines and maintains the shape of cell during development
3.4.2. provide mechanical support.
3.4.3. involved in the intracellular movement
3.4.3.1. eg. Golgi apparatus
3.4.4. component of cilia or flagella
3.4.5. spindle ( during cell division)
3.4.6. involved in the formation of centrioles
4. centrosome and centrioles
4.1. Centrosome
4.1.1. located near the nucleus
4.2. Centrioles
4.2.1. a pair orientated at right angles to centrosome.
4.2.2. size
4.2.2.1. small
4.2.2.2. hollow cylinders
4.2.2.3. about 0.3-0.5μm long
4.2.2.4. 0.2μm in diameter
4.3. Cell division
4.3.1. centrioles duplicated
4.3.2. 2 pairs migrate to opposites poles of spindle fibres
4.4. !Take note!
4.4.1. most plant cell lack centrioles
4.4.2. although they do produce spindles
5. cilia and flagella
5.1. Flagella
5.1.1. single and long
5.2. Cilia
5.2.1. short and many
5.3. common found in
5.3.1. unicellular organisms
5.3.2. small multicellular organisms
5.4. the microtubules undergo sliding motion ( beating movement)
6. microfilament
6.1. known as actin filaments
6.2. Functions
6.2.1. Provide mechanical support for various cell structures
6.2.1.1. The actin filaments are cross-linked with one another and with other proteins.
6.2.1.2. they form bundles of fibres