C-17-C Mitosis
rearrangements
In animal cells, M-Cdk promotes the ___ of the actin cytoskeleton and the Golgi apparatus
nuclear envelope
In animal cells, M-Cdk promotes the breakdown of the ___ ___
Polo-like and Aurora kinases
M-Cdk doesn't work alone; two additional families of protein kinases that contribute to control of early mitotic events
sister chromatid
M-Cdk must ensure that each ___ ___ is attached to the opposite pole of the spindle
assembly
M-Cdk must induce the ___ of the mitotic spindle
disassembly
M-Cdk phosphorylation of pore complexed initiates its ___ and their dissociation from the envelope
chromosome condensation
M-Cdk triggers it; the large-scale reorganization of the intertwined chomatids into compact, rod-like structures
tubulin subunits
Ndc80 links the microtubules to kinetochore but still allows for addition and removal of ___ ___
negative
___ checkpoint signal in spindle assembly checkpoint mechanism depends on several proteins, including Mad2
mitotic spindle
a bipolar array of microtubules, which pulls sister chromatids apart in anaphase
kinetochore
a giant, multilayered protein structure that is built at the centromeric region of the chromatid; attaches sister chromatids to spindle
centriole
a minute cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division.
Polo-like kinase or Plk
a protein kinase required for the normal assembly of bipolar mitotic spindle; it phosphorylates proteins involved in separation of the spindle poles
Aurora-A kinase
a protein kinase that also helps control proteins that govern the assembly and stability of the spindle
Aurora-B kinase
a protein kinase that controls the attachment of sister chromatids to the spindle
M-Cdk activity
activation of Polo-like and Aurora kinases are dependent on ___ ___
absence of centrosomes
another attachment mechanism that also plays a part
nuclear lamina
another component phosphorylated by M-Cdk; the structural framework beneath the envelope
Cdc20-APC/C activation
any kinetochore that is not properly attached to the spindle sends out a diffusable negative signal that blocks ___ ___ throughout the cell
opposite sides
at end of prophase in animal cells, centrosoms of growing spindle can be found on ___ ___ of nuclear envelope
prometaphase
breakdown of nuclear envelope, chromosomes begin to attach to spindle microtubules via their kinetochores and undergo active movement
microtubule-dependent motor proteins
cells that do not have centrosomes used these and other proteins to asociate microtubule minus ends to organize and focus the spindle poles
metaphase
chromosomes aligned in equator of spindle, kinetochore microtubules attach sister chromatids to opposite poles
cytokinesis
cytoplasm divided in two by contractile ring of actin and myosin filaments, which pinches the cell in 2, makes cleavage furrow
M-Cdk
drives entry into mitosis
colchicine or vinblastine
drugs that destabilize microtubules that arrest cells in mitosis for hours to days
pericentriolar matrix
each centrosome consists of a cloud of amorphous material called the ___ ___ that surrounds a pair of centrioles
senses tension
how a sensor mechanism in spindle assembly checkpoint works
1
how many microtubules bind to a kinetochore of a budding yeast cell
10-40
how many microtubules bind to a kinetochore of an animal cell
timing
in mammalian somatic cells, spindle addembly chekpoint determines the normal ___ of anaphase
coiled-coil proteins
in matrix; a microtubule-dependent motor protein that links motors to centrosome, structural proteins and components of cell cycle control system
y-tubulin ring
in matrix; component mainly responsible for nucleating microtubules
emdedded head-on
in metaphase, kinetochore microtubules are ___ ___ in special attachment sites
centrosome
in most somatic animal cells, an organelle near the nucleus of a cell that contains the centrioles and from which the spindle fibers develop in cell division.
unstable lateral attachments
initial attachments of microtubules to kinetochore; kinetochore attaches to side of passing microtubule with help from kinesin motor proteins
kinetochores
located at the centromere of each sister chromatid
spindle assembly checkpoint mechanism
mechanism that ensures cells do not enter anaphase until all chromosomes are correctly bi-oriented on the mitotic spindle
minus ends
microtubule ends that are focused at the two spindle poles
plus ends
microtubule ends that radiate outward from the poles
nuclear pore complexes
nuclear envelope breakdown is thought to begin when M-Cdk phosphorylates several subunits of the ___ ___ ___ in the nuclear envelops
nucleates
pericentriolar matrix ___ a radial array of icrotubules with their fast-growing plus ends projecting outward and their minus ends associated with the centrosome
kinetochore microtubules
plus ends of microtubules that are attached to sister-chromatid pairs at large protein structures called kinetochores
interpolar microtubules
plus ends of microtubules that overlap with plus ends of microtubules from other pole, resulting in an antiparallel array in spindle mid-zone
astral microtubules
plus ends of microtubules that radiate outward from the poles and contact the cell cortex, helping to position the spindle in the cell
Mad2
protein recruited to unattached kinetochores that act like enzymes and catalyzed conformation change in this protein to bind/inhibit Cdc20-APC/C
control of chromosome movement
regulation of plus-end polymerization and depolymerization at the kinetochore is critical for?
prophase
replicated chromosomes condense, mitotic spindle assembles , two centrosomes replicate and move apart; beginning of mitosis
Ndc80
rod-shaped protein complex that determines the attachment of each microtubule; anchroed in kinetochore at one end and interacts with sides of microtubule at the other
anaphase
sister chromatids synchronously separate toward spindle pole, kinetochore microtubules get shorter, spindle poles move apart
orientation
soon, dynamic microtubule plus ends capture the kinetochores in the correct end-on ___
sensor mechanism
spindle assembly checkpoint depends on this to monitor strength of microtubule attachment to kinetochore
chromosome segregation
the central event of mitosis
nuclear envelope breakdown
the completion of spindle assembly in animal cells require ___ ___ ___; a complex multistep process
short microtubules
these microtubules in vicinity of chromosomes become embedded in plus-end binding site of kinetochore, polymerize and grow away from it, cross-link to other minus ends, and focused by motor proteins at pole
metaphase-to-anaphase transition
transition stage whose progression is blocked by the spindle assembly checkpoint mechanism
telophase
two sets of daughter chromosomes arrive at poles and decondense, new nuclear envelope reassembles around each set, end of mitosis. contractile ring start to contract
phosphorylation
what does M-Cdk do to specific proteins to trigger various processes
small vesicles
what happens when envelope breaks down? envelope breaks down into
bombarded
when envelope breaks down, sister chromatid pairs are ___ by microtubule plus ends coming from two directions
removed
when last sister-chromatid pair is properly bi-oriented, the block is ___
cytoplasm
where centrosomes and microtubules of animal cells are located
nucleus
where many motor proteins and microtubule regulators that promote spindle assembly are located