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Cytoskeleton
WVSOM Class of 2012 Cytoskeleton
Question | Answer |
---|---|
cytoskeleton fibers from smallest to largest? | microfilaments, intermediate fibers, microtubules |
which of the cytoskeleton fibers are not motile? | intermediate filament |
energy for microfilament polymerization comes from? what about microtubules? | ATP, GTP |
components of microfilaments? microtubules? intermediate fibers? | actin and myosin; tubulin; keratins and nuclear lamins |
function of cytoskeletal bundles? networks? anchoring? | resilience against stretching; reslience against stretching and compression; anchoring the cytoskeleton via plaques and junctions |
motor proteins do what (motility) ? | hydrolyze ATP to crawl along filaments |
polymerization-depolymerization does what (motility) ? | increase or decrease filament length to induce pushing or pulling force |
the most abundant intracellular protein is what? | actin |
g-actin subunits become what? how? | f-actin filaments; ATP hydrolysis |
rope-like alpha helices that wrap around f-actin? | tropomyocin |
regulatory subunits binding tropomyosin and actin? | troponins c, t, and i |
actin crosslinking protein that forms networks in RBC's? | spectrin |
this crosslinking protein forms striated muscle networks? | dystrophin |
these microfilaments serve as motor proteins for actin? | myosins |
long bundles of microfilaments along basal surface of fibroblasts that have attached to a substratum, providing tension across a surface? | stress fibers |
energy for assembly of microtubules come from what? | beta GTP hydrolysis |
microtubule assembly process occurs more at which end? | positive end |
alpha and beta tubulins bind each other to form what? | dimers |
globular proteins that make up microtubules are what? | tubulins (alpha and beta) |
how many rows of tubulins per microtubule? | 13 |
rows of tubulins are called what? | protofilament |
Chemicals that interfere with microtubular assembly preferentially attack tumor cells because these rapidly dividing cells require microtubules for cell cycle progression. This is called what? | chemotherapy |
crosslinking proteins in microtubules are called what? | microtuubule associated proteins |
microtubule motor proteins are what 2? | Dynein and Kinesin |
what is the function of dynein? | moves flagella, cilia, cytosolic vesicles and bipartites associating with the mitotic spindle; it also moves vesicles, organelles and cytoskeletal fragments up and down axons |
what is the function of kinesin? | moves cytosolic vesicles and bipartites associating with the mitotic spindle |
examples of Microtubular Mediated Motility? | Intracellular membrane trafficking, Axonal Transport, flagella and cilia (cilia number in the thousands per sructure) |
what is the arrangement of microtubules within flagella and cilia? | 9 + 2 rule |
these objects between the doublets create the motor force with ATP hydrolysis: | dynein arms |
from cell body to a synapse is called? | anterograde transport |
from synapse to cell body is called? | Retrograde transport |
A structure similar to a centriole at the base of an individual flagellum or cilium | basal body |
what is the function of the cortical net inside the basal body? | believed to serve as nucleation centers for flagella and cilia outgrowth, they coordinate beating of cilia |
3 types of microtubules in mitotic apparatus? | polar, kinetochore, and astral |
outer ends of astral MT are what charge? inner end? | positive, negative |
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? | aster |
A protein structure joining centromeres to the microtubules of the spindle? | kinetochore |
during anaphase, what happens to the microtubules? | Chromatids are pulled to opposite poles of the spindle by depolymerization of microtubules at their + ends |
a small organelle consisting of a perpendicular pair of centrioles surrounded by a matrix of two proteins: | centrosome |
the core of a centrosome, consisting of 9 microtubular triplets, but not including the surrounding protein matrix: | centrioles |
All intermediate filaments consist of alpha helical cores with similar sequences. These are what? | gene family |
a major structural component of epithelial cells. Hair and nails consist of dead epithelial cells, mostly composed of this element: | keratins |
this links Z disks of striated muscle sarcomeres to each other and to the plasma membrane: | desmin |
two major distinctions between the assembly of intermediate filaments and that of microfilaments or microtubules? | no ATP or GTP is hydrolyzed; due to the antiparallel association of the tetramers there is no polarity |
intermediate filament crosslinking occurs using what structures? | intermediate filament associated proteins (IFAP) and ankyrin |
what is the function of ankyrin? | an IFAP that anchors desmin to the plasma membrane, as well as spectrin to the band 3 anion transporter of erythrocytes |
On the nucleoplasmic face of the nuclear envelope there is a meshwork of intermediate filaments known as the: | nuclear lamina |
the intermediate filaments are entirely what function? | structural |
3 examples of intermediate filaments are: | keratins, nuclear lamins, and desmins |
these are used to identify the origin of tumor cells, which often lose other distinguishing characteristics: | intermediate filament antibodies |
3 parts of nuclear lamina? | globular heads, alpha helical cores and tails |
which lamin remains bound to the vesicles? | B |
generally speaking what are the functions of all 3 components of the cytoskeleton? | provide structure and resilience; motility for all except intermediate filaments |
Factors that bind filaments together are called what? | cross-linking proteins |
in addition to hydrolyzing ATP and crawling along the microfilaments/microtubules, what else do motor proteins do? | carry a cargo along the filament (e.g. a vesicle) or they cause two filaments to slide past each other (e.g. muscle contraction) |
Finger like projections of the plasma membrane, supported by internal actin bundles: | microvilli |
what is the function of microvilli? | increase the surface area of the plasma membrane for absorption |
what is the most common myosin isoform? | myosin II |
myosin subunits are what structure? | tetramers |
myosin subunits consist of what two factors? | myosin light and heavy chains |
myosin heavy chains consist of what two things? | tails and globular heads |
two tails of myosin coil around each other to form dimers; this process uses what for energy? | ATP |
in the sliding filament model, contractions cause what to slide along what? | actin to slide along myosin |
Movement of vesicles through the intracellular membrane system is often directed along what two things? | actomyosin or microtubule filaments |
During telophase a ring made out of what material encircles an animal cell: | actomyosin |
ameboid movement is made possible by what structures? | microfilaments |
how are microtubules arranged with regard to polarity? | β subunits face the + end, α tubulins face the - end |
these structures are filled with microtubule bundles: | axons |
centers for the initiation of microtubule formation are called what? | microtubule organizing centers (MTOC) |
this structure is a combination of the spindle and asters: | mitotic apparatus |
when do centrosomes duplicate? | during the S phase |
which MT radiate from the centrosomes? | astral MT |
which MT extend halfway across the spindle? | polar MT |
which MT extend across the entire spindle from aster to aster (chromatids attache here)? | kinetochore MT |