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The Cytoskeleton. Honors Biology Monkemeier Unit 4: Microscopes, Cell Structures and Functions, The Tree of Life. The Cytoskeleton.
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The Cytoskeleton Honors Biology Monkemeier Unit 4: Microscopes, Cell Structures and Functions, The Tree of Life
The Cytoskeleton • The cytoskeleton of all eukaryotic cells is crisscrossed by a network of protein fibers that supports the shape of the cell and anchors organelles to fixed locations. • The network of protein fibers that compose the cytoskeleton is a dynamic system, constantly forming and disassembling.
Three Types of Fibers Compose Cytoskeleton • Actin Filaments (Microfilaments) • Actin filaments are responsible for cellular movements such as contraction, crawling, pinching during division, and formation of cellular extensions.
Microtubules • Microtubules are the largest of the skeletal elements. • Along with facilitating cellular movement, microtubules provide organization to the cytoplasm and are responsible for moving materials within the cell itself.
Intermediate Filaments • These filaments, once formed, are stable and usually do not break down. • Intermediate filaments include: vimentin, keratin, neurofilaments • Note the differences between intermediate filaments and microtubules or microfilaments.
Working Together • The three fibers of the cytoskeleton interact with each other to modulate cell shape and permit cell movement and to act to move materials within the cytoplasm.
Cytoskeleton • Functions as structural support; cell movement; movement of vesicles within cells. • It is present within the cells of all four eukaryotic kingdoms: Protista, Fungi, Plantae, Animalia
Centrosomes • Animal cells and most protists contain a pair of structures known as centrioles. • These centrioles are barrel-shaped and are located near the nucleus. • The area within the cytoplasm that contains the centrioles is known as the centrosome.
Centrosomes • The centrosomes of animal cells and protists function as microtubule-organizing centers. • They are also responsible for the reorganization of microtubules during cell division. • Plants and Fungi do not have centrosomes, but they do have microtubule-organizing centers.