For eukaryotic cells:
* Cilia and Flagella: These hair-like projections extend from the cell surface. Cilia are short and numerous, creating a wave-like motion for movement or to move fluids past the cell. Flagella are longer and fewer, providing a whip-like motion for locomotion. Both structures are made of microtubules arranged in a 9+2 pattern.
* Pseudopodia: These temporary, finger-like projections of cytoplasm are used for amoeboid movement. They are formed by the polymerization and depolymerization of actin filaments in the cell's cytoskeleton.
* Microtubules: These long, hollow tubes are important for intracellular transport and cell division. They also contribute to the movement of cilia and flagella.
For prokaryotic cells:
* Flagella: Prokaryotic flagella are simpler than eukaryotic flagella and consist of a protein filament called flagellin. They rotate like propellers, propelling the cell through the environment.
Other mechanisms:
* Cytoplasmic streaming: The movement of cytoplasm within a cell can contribute to cell movement, especially in amoeboid cells.
* Muscle cells: Specialized cells in multicellular organisms contract and relax, enabling movement of the whole organism.
Examples:
* Sperm cells use flagella to swim towards the egg.
* Paramecia use cilia to move through water.
* Amoebas use pseudopodia to crawl over surfaces.
* White blood cells use amoeboid movement to squeeze through blood vessels and reach infection sites.
It's important to note that the specific structures and mechanisms involved in cell movement can vary greatly depending on the cell type and its function.
