| 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. |
| 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 |
| 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 basal body's function? |
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 |
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