Term
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Definition
Often considered an organelle
Dynamic
Organizes cell structures
Supports and strengthens cell morphology
Composed of three networks of fibers
-Actin Filaments
-Intermediate Filaments
-Microtubules |
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Term
Actin Filaments (Micro Filaments)
4-6 nm |
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Definition
**involved cell migration (TRANSPORT)
-Muscle contraction
-Often MOST ABUNDANT protein in the eukaryotic cell
-Composed of actin
Two forms of actin:
"G-actin" a globular monomer
"F-actin" a linear polymer of G-actin subunits
-ATP hydrolysis not essential for polymerization but REQUIRED for depolymerization |
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Term
Intermediate Filaments
7-11 nm |
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Definition
-STRUCTURALLY DIVERSE
5 major classes
-DEVELOPMENTALLY REGULATED
-CELL SPECIFIC EXPRESSION
-does not require phosphate energy for assembly (REQUIRE NO ENERGY TO BUILD THE FILAMENT)
-Insoluble molecule
-lines the inner nucleus membrane
-MOST STABLE of 3 classes of filament |
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Term
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Definition
-Require ATP to polymerize
-Splitting chromatin during mitosis
-Composed of Tubulin (a alpha, B beta)
a-tublin binds GTP irreversibly and does not hydrolyze
B-tubulin binds GTP reversibly and hydrolyzes to GDP |
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Term
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Definition
| If the rate of the ON reaction is faster than the OFF reaction in the hydrolyzation of ATP to ADP. |
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Term
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Definition
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Term
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Definition
motor molecules that move various types of vessicles along MICROTUBULE tracks.
ATP dependent
The hydrolysis of ATP to ADP causes a conformational change in the kinesin that results in forward movement. |
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Term
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Definition
9 + 2 structure : an axoneme
Movement of cilia and flagella is dependent on a kinesin type molecule called dynein |
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Term
| QUICK FACTS FROM Lecture 9: The Cytoskeleton |
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Definition
-Actin filaments utilize ATP.
-Intermediate filaments utilize self assembly and do not use either ATP or GTP.
-Microtubules utilize GTP. |
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Term
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Definition
Contributes to Cell Motility
After the ATP-G actin monomers are incorporated into a filament, the bound ATP is slowly hydrolyzed to ADP.
Thus, most of the filament consists of ADP-F actin.
The end of the (+) filament contains ATP-F actin.
ATP hydrolysis is not essential for polymerization. REQUIRED to promote DEPOLYMERIZATION. |
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Term
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Definition
| results from dynamic polymerization-depolarization of polarized filaments |
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