lecture 10and 11 Flashcards
______ _______Provide mechanical strength to cells and organelles
intermediate filaments:
Intermediate filaments are so named because they are intermediate in size between microtubules and actin filaments
ture
Intermediate filaments assemble
Dimers, then tetramers then multimers forming filaments
Which type of protein will handle phosphorylation of the nuclear lamins
kinase
what are the 3 filament systems
intermediate, microtubles, actin
Intermediate filaments act as a ______ or_____to provide mechanical strength to cells and organelles
scaffold or network which are Extensive and very stable assembly interactions
keratins provide stength to ___
skin
Nuclear lamins provide strength, support
and integrity to
nuclear membrane
Nuclear lamins on ____ ____ of the nuclear envelope
the inner face
Dynamics of the nuclear lamins are regulated by _____&________through the cell cycle
phosphorylation and dephosphorylation
______&________mediated degradation of a subunit of the “cell cycle controller”
Ubiquitin and proteasome
All filament systems are _____ that is subunits assemble and disassemble–these processes are further regulated by the cell
dynamic,
are intermediate filaments more or less dymaic than All filament systems are dynamic, that is subunits assemble and disassemble–these processes are further regulated by the cell
less
microtubules and actin filaments are regulated by similar activities
Nucleotide binding and hydrolysis on growing end of the filament
Proteins acting to influence filaments or monomers
actin filaments are bound with
ATP at the end
microtubles are bound wiht
GTP at the end
Microtubules are composed
of ab-tubulin heterodimer subunits forming protofilaments
The “__” ends of microtubules which favor continuing addition of subunits are found at the centrosome.
negative
The small, orthogonal or perpendicular structures at the center of the MTOC shown below are termed
centrioles
gamma tubulin is located:
at centrosomes
Dynamic instability of microtubules refers to the fact that:
Unless capped or stabilized microtubule ends grow rapidly but can and also do suddenly shrink
_______ are microtubule motor proteins that use the energy of ______ to move along microtubules
Dyneins : ATP hydrolysis
Which of the following is not a function of the microtubule cytoskeleton
Provide mechanical strength to cells in tissues
Microtubules - functions(5)
Create polarity in cells Arrange and move organelles Tracks for vesicle movement by motor proteins Cell division Cell motility
Addition of ab heterodimers to growing ends of microtubules depends on
GTP or GDP bound state of tubulins at those ends
nucleators are
Proteins acting to influence filaments or monomers
Microtubules are organised and regulated much like
actin
Microtubule + end growth or shrinkage is
regulated by
GTP binding and hydrolysis
In most cell types the plus or growing ends of microtubules are oriented toward the _______and away from the MTOC (microtubule organizing center)
cell periphery
Microtubules create
polarity
Individual microtubule ends, unless capped or protected are constantly either
growing or shrinking
Structure of microtubules
ab tubulin heterodimer,Protofilament
In or at which structure does gamma-tubulin act as a nucleator of microtubles in many cell types:
centrosomes
Capping proteins can____plus ends from depolymerization to make a stable array of microtubules
stabilize
Neurons are a great example of where microtubules function to form tracks for directed transport by ____ motor proteins
vesicle
____&____ are microtubule based motors
kinesins and dyneins
Motor proteins move cargo on microtubules in a
specific direction towards the + end
myosins, the motors of the actin filaments, ____ associate with the filament and light chains control specific cargo binding
heads
Microtubules can mediate cell motility via their roles in forming
cilia or flagella
Movement is produced by _____ coordinated regulation ofmotors between the outer doublets microtubules
dynein
MTOCs of cilia and flagella are ___ ____which are functionally and compositionally related to centrioles.
basal bodies
______________&___________is a highly regulated collaboration of DNA and proteins associated with the microtubule cytoskeleton
Cell division and chromosome segregation
drug Colchicine
monomer binding
prevents assembly into filament
Taxol
filament binding
prevents disassembly
