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55 Cards in this Set
- Front
- Back
Microtubules play a role in _cellular movement during the interphase and mitosis. the movement is largely due to _ and _ motor proteins. In addition to the functions listed, MTs also cause movement of _ and _.
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intra
kinesin, dynein cilia, flagella |
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Cytoskeletal components and functions:
(_), _ _ - organizaing cell polarity _ _- chromosomes movements MT assembly _ _- + end-directed vesicle and chromosome transport _ _- - end-directed vesicles and transport spindle assembly |
MTOC, spindle pole
microtubule dynamics kinesin motors dynein motors |
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Cytoskeleton systems: Microfilaments:
_ binds ATP, form rigid gels, _, and linear _. There is regulated assembly from a large number of locations so they are highly _, _, tracks for _, and the contractile machinery and network at the cell _. |
Actin
networks, bundles dynamic polarized myosins cortex |
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Cytoskeleton systems: Microtubules: _-_ _ bind to GTP and are rigid and not easy to bend. They are regulated assembly from a small number of locations, and highly _, _, make tracks for _ and _; and control the organization and long-range transport of _.
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alpha-beta tubulin
dynamic polarized kinesins and dyneins organelles |
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Cytoskeleton systems: Intermediate filaments: _ subunits don't bind a nucleotide. They have great _ strength and are assembled into pre-existing filaments. They are less _, _, have no _, and are used for cell and tissue integrity
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IF
tensile dynamic unpolarized motors |
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_ _ subunits compose the wall of a microtubule. alpha tubulin-GTP (-) is irreversible binding but _-_ can block exchange, The beta-tubulin-GDP (+) can exchange for _. fig 18.3 dimers of alpha-tubulin and beta-tubulin form _ which combined the structure is _.
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heterodimeric tubulin
beta-tubulin GTP protofilaments stiff |
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Arrangement of protofilaments in _, _ , or _ microtubles. They are packed side-by-side to form the wall of the MT. fig 18.4
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singlet, doublet, or triplet
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Microtubules are assembled from _ _ _ (_). The polar end is on the _ end and the growth occurs on _ end. fig 18.5
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mictrotubule organizing centers (MTOCs)
- + |
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The _-_ _ _ (_) nucleates polymerization of tubulin subunits. MTOCs have high conc of proteins necessary for initiating assembly of MTs. This includes the _ that is thought to nucleate assembly of protofibrils into sheets and tubes via contacts with _-_. fig 18.7
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gamma-tubulin ring complex (y-TuRC)
(y-TuRC) alpha-tubulin |
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A centrosome is a (_) and has a triplet structure. fig 18.6
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MTOC
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Microtubule assembly and treadmilling: MTs have structural and functional _. Growth occurs at + end because it has a lower _. Beta-tubulin-_ is hydrolyzed to beta-tubulin-_ in the MT interior
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polarity
Cc GTP GDP |
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Microtubule assembly and treadmilling: bc growth occurs at + end, dimer treadmills from _ end to _ end. fig 18.8
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+
- |
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dynamic instability is an _ property of MTs as they rapidly grow and shrink independently. _ is faster than assembly. fig 18.10
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intrinsic
disassembly |
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The ends of the growing and shortening MTs appear different. fig 18.12 Growing ends are _ and _ attach here. shortening ends are _, and this splaying probably promotes diassembly. It is explain by GTP cap model.
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smooth
protofilaments frayed |
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GTP cap model has been made to explain dynamic instability: beta-tubulin-_ disassembles faster than beta-tubulin-_.Mts with cap seem to grow and those lacking will fall apart.
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GDP
GTP |
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MT-associated proteins (_) modulate MT behavior. _, _, and _ are regulated by these. MT spacing depends on length of side-binding MT-stabilizing MAP "_ _" arms. Certain drugs affect this like _/_ which blocks MT dynamics at metaphase and also depolmerizes MTs; _ which stabilizes MTs, is used as _-_ drug. blocking MT dynamics can prevetnt passin through the _ _. fig 18.14
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MAPs
assembly, disassembly, and association projection domain anti-cancer cell cylcle |
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MT-associated proteins (MAPs) modulate MT behavior. some MAPs destabilize MTs by severing them using _ or by binding MT frayed ends or tubulin dimers. Many MAPs are negatively regulated by _. fig 18.16
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ATP
phosphorylation |
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Different proteins are transported at different rates along axons: classic _-_ experiment showed MT-dependent axonal transport. Axon slices are subjected to _-_ to identify radiolabeled proteins.
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pluse-chase
SDS-PAGE |
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Different proteins are transported at different rates along axons: (3)
1_ tranport fastest. 2_ have intermediate rates 3_ and _ (IF) subunits are the slowest |
vesicle
organelles tubulin and neurofilament |
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Transport goes both directions along MTs in axons: _-goes down the cell body to axon and _ goes via synaptic terminals to the cell body.Vesicles can be transported both directions along same MT and can pass each other.
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anterograde
retrograde |
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Motor proteins are at both + and - ends but _ only has + ended directed myosin motors. fig 18.18
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actin
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The structure of the kinesin microtubule motor protein:
Head binds MT and _. Linker converts _ _ into movement. Stalk dimerizes?? Tail has _ _ binding which has cargo binding. fig 18.19 |
ATP
ATP hydrolysis light chain |
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Kinesin is a _ end-directed motor that goes toward + end and away from MTOC. There are cytosolic kinesins and mitotic kinesins and some mitotic ones are - end directed motors.
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+
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Structure and function of select kinesin family members: fig 18.21
Kinesin-#_ and Kinesin-#_ for organelle transport. Kinesin-#_ is bipolar and used in mitosis. Kinesin-#_ is for end assembly. |
1/2
5 13 |
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Kinesin is:
_ end directed motor head binds to _ neck is _. bind _s used in _ process for _ and _ transport |
+
ATP flexible MTs mitosis vesicle and organelle |
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Myosin:
_ end directed motor head binds to _ neck is _ bind the _s used in _ and for _ and _ transport |
+
ATP rigid MFs sytokinesis vesicle and organelle |
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_ are - end directed motors for retrograde transport.
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Dyneins
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Dynein MT motor proteins: completely different structure: _/_ complexes are huge and much dif in structure and organization than kinesins and myosins
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dynein/dynactin
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Dynein MT motor proteins: completely different structure:
_- heavy, intermediate and light chain subunits fig 18.24 _- glued: binds dynein and MTS, _ holds 2 halves of dynactin together, _ _ _ (_) binds cargo and dynamtin. fig 18.26 |
dynein
dynactin dynamitin Arp1 |
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Dynein on a MT: _ _ drives movement by changing the orientation of the head relative to the stem, causing movement toward + end
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ATP hydrolysis
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Organelle transport by MT motors: switching bn cystolic _ and _ will reverse cargo transport direction. fig 18.27
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kinesins
dyneins |
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Multiple motor proteins can move the same cargo: motor of dif types can be on the same cargo: There can be coorperation bn _ and _ motors. e.g. moving from cell body (MT-rich) to the cell cortex (MF-rich) -> cooperation bn _ and _ at the cell cortex.
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MT and MF
myosin and kinesin |
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All eukaryotic cilia and flagella contain bundles of _ _ _ studded with axonemal _. fig 18.29 the _ arms slide the outer doublet MTs to generate axonemal _ in which axonemal dynein anchored on the A-tubule pulls on the B-tubule ( goes toward _ end) fig 18.31
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doublet MTs
dyneins beating - |
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Cilia and flagella emanate from _ bodies with _ MTs. _ _ moves material up and down cilia and flagella. fig 18.29 and 18.32
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basal
triplet Intraflagellar transport |
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The stages of mitosis and cytokinesis in an animal cell: MT _ play a key role in segregating chromosome. fig 18.34
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dynamics
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The stages of mitosis and cytokinesis in an animal cell: Metaphase: There are 3 classes of MTs: (3) MT dynamics increase dramatically during _. fig 18.36
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Kinetochore MT
Astral MT Polar MT mitosis |
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The _ is a specialized MT attachment site at the chromosome centromere. MT _ end interact with kinetochore proteins to capture and help transport _.
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+
chromosomes |
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The kinetochore is a specialized MT attachment sit at the chromosome centromere: The proteins interact with _ _ of the centromere and include _ _ proteins. The kinetochore is the only site of attachement bn _ and _. fig 18.39
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repetitive DNA
MT motor MTs and chromosomes |
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Duplicated centrosomes align and begin separating in _. Replication begins in late _ phase and is complete by _ phase, but migration to opposite sides of the nucleus does not occur until _. fig 18.35
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G1
G2 prophase |
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Organization of the spindle poles orients the assembly of the _ _; the kinetochore capture sets the stage for _.
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mitotic apparatus
metaphase |
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Mitotic motor proteins (_ and _) and increased _ instability of MTs play key roles in forming the metaphase mitotic spindle. Tension from both poles via _ MTs aligns chromosomes at the metaphase plate. fig 18.40
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kinesins and dyeins
kintechore |
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Anaphase A: Kinetochore MT _ occurs as chromosome _. MTs shorten at _ end by kinetochore-assoc kinesin and MTs shorten at _ end by spindle pole-assoc kinesin. In total MTs stay _ to kinetochore. fig 18.41
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shortening
separate + - attached |
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Anaphase B: Poles move apart due to combined action of _ walks along polar MTs towards + ends (pushing poles apart) and _ at PM pulls on poles. Polar MTs elongate so pushing can go further. fig 18.41
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kinesins and dyneins
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Cytokinesis is caused by a _ _ of actin and myosin II. The region of _ MT overlap (sand dollar) or _ MT overlap (vertebrate) bn the two spindles delivers or activates contractile ring _. Following second cleavage the _ MT overlaps. Spindle MTs determine _ _. Contractile ring regulation involves inhibitory and activating _ of a myosin light chain
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contractile ring
astral spindle regulators astral cleavage plane phosphorylation |
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Plant cells have many MTOCs: parallel arrays of cortical MTs direct _ _, which in turn determines the direction of cell _. In mitosis, MTs reorganize intos a _ _ around the nucleus where spindle is similar to that in an animal cell but has no _.
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cellulose deposition
expansion cortical bundle centromeres |
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Plant cells have many MTOCs: Cell division involves _ _ formation (cell plate) rather than a _ _ (golgi derived). MT network at cell ends remains intact. fig 18.43
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cell wall
contractile ring |
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Intermediate filaments: Functions and structure distinguish them from other in cytoskeleton. 10nm in diameter.
Structural- no association with _ _, do not drive cell movement. Stable- don't easily _. They don't bind _ (vs MFs: ATP/ADP AND MTs: GTP/GDP). Usually associated with _ _, also often parallel MTs |
motor proteins
depolymerize nucleotides cell membranes |
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Many IF proteins are cell-type specific and others are ubiquitous: These are useful for indentifying the tissue of origin of metastasized tumors.
Class I and Class II- acidic and basic _ in epethelial cells for tissue _ and _. e.g. desmosomes Class III- _, _, and _ in muscle, glial cells, and mesenchymal cells for _ organization and _. e.g. dense bodies in smooth muscle and z-disk in skeletal muscle Class IV- _ (NFL, NFM, NFH) in neurons for _ _. e.g. axon Class V- _ in nucleus for nuclear _ and _. e.g. nucleus |
keratins
strength and integrity desmin, GFAP, vimentin sarcomere, integrity neurofilaments axon organization lamins structure and organization |
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All IF proteins have a conserved _ _ and are organized similarly into filaments.
They are _-_ with globular N and C-terminal domains. Monomers form _ _ . Dimers form staggered _-_ _. therefore IFs are _, unlike MFs and MTs fig 18.45 |
conserved core
alpha-helical parallel dimers anti-parallel tetramers symmetric |
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All IF proteins have a conserved core domain and are organized similarly into filaments. Tetramers join end-to-end to form _. Four protofibrils coil around each other to form an _. coiled like a _. Globular N and C domains protrude from IF surface hence the _ _. fig 18.45
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protofibrils
IF rope beaded appearance |
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Intermediate filaments are dynamic polymers in the cell: although IFs are more _ than MFs and MTs, they undergo assembly and dissambly in vivo.
_ subunits slowly undergo exchange The nuclear _ disassembles during nuclear envelope breakdown during _ and this is regulated by lamina _. fig 18.46 |
stable
Keratin lamina mitosis phosphorylation |
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Defects in lamins and keratins cause many diseases: _ _ occurs when keratin is absent in epidermal cells so they are more susceptible to mechanical damage and the epidermis readily separates from the underlying dermal layer.
The role of keratin is purely _. IFs also anchor cells to the matrix at cell juctions, giving _ _ to epithelial sheets. |
excessive blistering
structural mechanical strength |
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Defects in lamins and keratins cause many diseases: lamin assoc diseases: include muscular _ and premature _.
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dystrophies
aging |
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_ and associated proteins stabilize sarcomeres in skeletal muscle. Structural role is not involved in _ _.
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desmin
force generation |
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Intermediate Filaments- associated proteins (IFAPs) contribute to _ _.
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cellular organization
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