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Cytoskeleton
thatcher
| Question | Answer |
|---|---|
| a system of interconnected components that interact in a dynamic manner to form a functional structure. it is composed of discontinuous and continuous components. | tensegrity |
| in tensegrity, the discontinuous components resist what? | compression |
| in tensegrity, the continuous components resist what? | stretching |
| in human body, what is the discontinuous components? | bones |
| in human body, what do bones resist? | compression |
| in the human body, the continuous components are what? | ligaments and tendons |
| ligaments and tendons resist what? | stretching |
| which components of the cytoskeleton define the cell shape and provide resilience to cells? | microfilaments, microtubules, intermediate filaments. |
| which compoenents of the cytoskeleton are used for motility? | microfilaments and microtubules only |
| factors that bind filaments together | crosslinking proteins |
| filaments crosslinked into thtree dimensional, crisscrossed meshworks, that can resist both stretching and compression | networks |
| filaments crosslinked in parallel to form fibers that resist stretching | bundles |
| when filaments are attached to the plasma membrane by plaques or junctions that consist of specialized adherence proteins. these junctions serve to attach the cytoskeleton, attach cells ot the basal lamina...etc. | anchoring |
| what are two mechanisms of motility for cells? | motor proteins hydrolyze ATP and crawl along microfilaments or microtubules. another is polymerization/depolymerization: filament length is increased by polymerization to produce a pushing force, or decreased by depolymerization to induce a pulling force. |
| this is the most abundant intracellular protein, and it is a structural microfilament | actin |
| how is actin assembled? | G actin subunits polymerize into double helical F actin filaments due to ATP hydrolysis, producing an actin microfilament. |
| what are the two crosslinking proteins for microfilaments? | spectrin (actin crosslinking protein that forms networks in erythrocytes) and dystrophin (forms striated muscle networks) |
| Duchenne muscular dystrophy is a sex linked mutation of which gene? | dystrophin |
| what's one example of a structural use of actin? | microvilli. they are finger like projections of the plasma membrane, supported by internal actin bundles. they increase the surface area of the plasma membrane for absorption |
| these microfilaments serve as motor proteins for actin. some sserve a structural role as well. | myosins |
| describe the subunits of myosin | they are tetramers of myosin heavy and light chains. heavy chains consist of alpha helical tails and globular heads. the two tails coil around each other to form a dimer. heads provide motor force. light chains control contraction of globular heads. |
| describe the sliding filament model | ATp hydrolysis activates a conformational change of myosin heads. these contractions cause myosin to rawl along actin, and microfilaments slide past each other to induce contraciton. |
| give some examples of microfilament mediated motility | intracellular membrane trafficking, muscle, contractile ring of cytokinesis, amoeboid motion, stress fibers |
| globular proteins that make up microtubules. there are two forms: alpha and beta | tubulins |
| how are microtubules assembled | the alpha and beta tubulins bind each other to form dimers. the dimers then bind end o end to form hollow microtubules as a result, they are polarized. beta units face the + end and alpha units face the - end. |
| how many rows of alpha and beta dimers are there per microtubule? | thirteen. they are known as protofilaments. |
| microtubule assembly requires energy from this molecule | GTP. |
| does microtubule assembly occur more rapidly at the positive or negative end? | positive |
| in this type of treatment, drugs are given that interfere with microtubular assembly, and they preferentially attack tumor cells because the rapidly dividing cells require microtubules for cell cycle progression. | chemotherapy |
| these are microtubular crosslinking proteins that form networks | MAP's. |
| what are two motility motor proteins for microtubules? | dynein and kinesin |
| this motor protein of microtubules moves flagella, cilia, cytosolic vesicles and bipartites associating with the mitotic spindle. it also moves vesicles, organelles and cytoskeletal fragments up and down axons. | dynein |
| this microtubule motility protein moves tytosolic vesicles and bipartites associating with the mitotic spindle. | kinesin |
| give some examples of microtubular mediated motility | intracellular membrane trafficking, axonal transport, flagella and cilia |
| describe the 9+2 arrangement for flagella and cilia. | they consist of nine microtubule dublets with a central microtubule doublet. Dynein arms between the doublets create the motor force with ATP hydrolysis. the entire structure is enclosed by the plasma membrane. |
| this is a structure similar to a centriole at the base of an individual flagella or cilia. they are believed to serve as nucleation centers for flagella and cilia outgrowth. they are located on the cytoplasmic side of the plasma membrane. | basal body |
| all microtubules and associated factors are involved with what process | chromatid separation |
| a small organelle consisting of a perpendicular pair of centrioles surrounded by a matrix of two proteins | centrosome |
| this is the core of a centrosome, consisting of nine microtubular triplets, but not including the surrounding protein matrix | centriole |
| centers for the initiation of microtubule formation. microtubules grow by adding subunits to preassembled tubulin, so they require some source of tubulin to serve as nucleation centers. in animal cells centrioles probably serve this purpose. | microtubular organizing centers (MTOC) |
| spindle and asters make this | mitotic apparatus |
| spindle shaped complexes of microtubules, which serve to separate daughter chromosomes during mitosis | mitotic spindle |
| an area at each end of the spindle where the microtubules converge. centrosomes duplicate during S phase. during prophase they separate to opposite poles of the nucleus. there they serve as MTOCs organizing microtubules into asters | asters |
| three microtubules are known as this | astral microtubule |
| a protein structure joining centromeres to the microtubules of the psindle. | kinetochore |
| in this phase of mitosis, chromatids are pulled to opposite poles of the spindle by depolymerization of microtubules at their positive ends. this is the end that contacts the kinetochores | anaphase |
| these are entirely structural components of the cytoskeleton | intermediate filaments |
| all IF consist of alpha helical cores with similar sequences. this defines the different IF's as this | gene family |
| give two examples if IF's | keratins, nuclear lamins |
| this IF is a major structural component of epithelial cells. hair and nails consist of dead epithelial cells, mostly composed of this | keratins |
| how are iFs used in cancer diagnosis? | IF antibodies are used to identify the origin of tumor cells, which often lose other distinguishing characteristics. |
| how are iF's assembled? | the cores coil around each other to form dimers. these then associate into higher order protofilaments and eventually into intermediate filaments. |
| what are two major differences between the assembly of IF and the assembly of microfilaments and microtubules? | not energy is used in IF synthesis because it is a spontaneous process. IF's do not have polarity |
| what are IF crosslinking proteins called? | IFAPs (intermediate filament associated proteins) |
| this is an IF crosslinking protein that anchors desmin to the plasma membrane, as well as spectrin to the band 3 anion transporter of RBCs | ankryn |
| on the nucleoplasmic face of the nuclear envelope there is a meshwork of intermediate filamens known as this | nuclear lamina. there are three forms, lamins A, B, and C |
| where are each of the lamins located? | lamins A and C are released into the cytosol, while Lamin B remains bound to vesicles. |
Created by:
aferdo01
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