BIOL 122 1/27 Cells Cont. (End)

Cytoskleton
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Terms in this set (21)
Cytoskleton
Holds things in place in the cell.
Three main components:
- microfilaments
- intermediate filaments
- microtubules
Microfilaments (actin filaments)
Two intertwined stands of the protein actin, used in cell support and movement, pinching during cell division. Dissolve and form readily, smallest, 7 nm in diameter.
Image: Microfilaments (actin filaments)
Intermediate filaments
stabilize organelles, once formed they are permanent structures, intracellular tendons. Intermediate size, 8-10nm in diameter. Keratin- one class found in epithelial cells, hairs, and nails
Microtubules
Hollow tubes. Spiral strands of protein molecules that form a tubelike structure. Composed of ring tubulin protein fibers. Multiple functions: moving materials within the cell, allowing cellular movement, chromosome movement in cell division. Constantly being deformed and regraded. Largest, 25 nm in diameter. Format MTOC
Image: Microtubules
Centrioles
Where microtubules are assembled. Found in most animal and many protist cells. Located near the nucleus at right angles from one another. In the centrosome region.
Image: Centrioles
Cell movement
Cell motion involves actin microfilaments and microtubules. Can move by:
1) crawling
2) material within a cell
3) flagella and cilia
Cell movement- crawling
Use of pseudopods amoeba or white blood cells, extends and uses actin microfilaments
Image: Cell movement- crawling
Cell movement- within a cell
Formation and disassembly of actin microfilaments allows cytoplasm streaming in plant cells, allows faster distribution of materials.
motor proteins of microtubules
kinesin and dynein
Image: motor proteins of microtubules
Cell movement- flagella and cilia
Have a similar structure, both have a core of microtubules sheathed by the plasma membrane.
Image: Cell movement- flagella and cilia
Structure of flagella and cilia9+2 arrangement; dyenin connects outer-parts to one another, nine doublets, 2 singles of microtubules, motor proteinsBasal bodyanchors the cilium or flagellum, structure is identical to a centrioleThe bending of the cilia and flagella is driving by the arms of what?The motor protein, dynein Dynein arms grab, move, and release microtubules Protein cross-links limit slidingCilia usually occur in large numbers on the cell surface. Same with flagella, but are _____shorter, (2-20 microns long)MicrovilliUsed to increase the surface area of the cell (as in the epithelial cells of the digestive tract)How many flagella are in each cell?One or a few, same width as cilia but are longerPlant cellPlant cellsClose to an animal cell, however has a cell wall, central vacuole, and plastids.Cell wallStructural strength, limit water absorption, and protection. Composition is cellulose and lignin.Central vacuoleStoring nutrients and water, involved in metabolism, retains and regrades waste, and some color.PlastidsGather and store nutrients, pigments, photosynthesis, such as chloroplasts.