cytoskeleton Flashcards
the cytoskeleton is a system of _______ that provide for the architecture, shape and motility of cells and for the direct movement of ______ and ______
protein polymers, organelles, molecules
components of the cytoskeleton include ________, __________, ___________ and a host of ________ and ___________ proteins
microtubules, microfilaments (actin), intermediate filaments, accessory, regulatory
microtubules are composed of _______ dimers made up of ________ and ______
tubulin, alpha, beta tubulin
tubulin is a _______
GTPase
microtubules are hollow with an outside diameter of ______
24 nm
accessory proteins called __________ stabilize and space the polymers and ________ between cytoskeletal elements
microtubule-associated proteins (MAPs), regulate interactions
microtubules are highly ______ if not stabilized and can undergo rapid bouts of assembly and disassembly
dynamic
microtubules act as _______ for microtubule based motor proteins to transport cargo
substrate
microtubules are _______ polymers with a plus end and a minus end
polarized
the plus end of the microtubule is _______ with _______ rates of tubulin addition and removal and is the end closest to the cytoplasm
dynamic (lengthens and shortens), faster
the minus end of a microtubule is embedded in the ________ and has _____ rates of tubulin addition
centrosome, slower
microtubules make up the _________, provide a road for transport in most ______ cells, the key determinate of cell _________, very important in _______ for shape and axonal transport, and provide a backbone for _______ and _______
mitotic spindle, interphase, shape, neurons, cilia, flagella
microtubules are composed of _____ protofilaments which are stacks of tubulin dimers
13
the polymerization phase of the microtubule is considered the _______ phase where ______ is needed for building and is attached
rescue, GTP
the depolymerization phase of the microtubule is considered the _______ phase where ______ is attached when breaking down due to a loss of a phosphate
catastrophe, GDP
the two microtubule associated motor proteins include ______ and _______
dynein, kinesin
on a microtubule, dynein moves towards the ______ end while kinesin moves towards the ______ end while both using ATP to move
negative, plus
the head domain of microtubule associated motor proteins is attached at the ______ and “walks” along it
microtubule
the light and or intermediate chains of the microtubule associated motor proteins decide _________, regulates the _________ and the ______
what cargo will be carried, motor protein, speed
microtubule structural non-motor proteins function to _______, regulate ________, and regulate ________ example is ______
organize, stability, dynamics, tau and MAP-1,2,3,4 etc
nucleation is the process of creating a cytoskeletal polymer or_________ from scratch
microtubule
polymerization is the _______ of a cytoskeletal polymer following nucleation
elongation
nucleation occurs at the _______ and it is located near the ______
centrosome, nucleus
a centrosome is composed of two cylindrical structures called ______, arranged ________ to each other and surrounded by a protein rich matrix known as the ________
centrioles, perpendicular, periocentriolar material
gamma tubulin is required only for _______ of microtubules and is only found in the ________
nucleation, centrosome
cilia and sperm tails are _______ based structures used for movement
microtubule
the basal body is the ______ center and _______ organizing center for cilia and flagella
nucleation, microtubule
the _______ is the 9+2 microtubule structure of cilia and flagella
axoneme
_____ drives the axonemal motility of of cilia and flagella inside the axoneme
dynein
immotile cilia syndrome is a body wide defect in axonemal structure that results in obstructive ____ disease and ______ males
lung, sterile
_________ syndrome is a combination of situs inversus (reversal of normal body asymmetry) and immotile cilia syndrome
kartageners
In cancer cells, microtubules are ______ in therapeutics in order to try and block cell division
targets
lissencephaly (smooth brain) is caused by mutations in the microtubule proteins _____ and ______, is the inability of microtubules to move and fold the brain
L1S1, doublecortin
neurodegenerative disorders are abnormalities/mutations in ______, _______, _______ and ________
tau, dynein, kinesin, spastin
charcot marie tooth disease type 2A
a neurological disease caused by mutations in a specific kinesin
neurotopic viruses exploit the neuron’s microtubule based _______ to reach cell bodies and infect it, the vectors bind to the _______
transport system, motor proteins
microfilaments are non-hallow polymers of the globular protein ________
actin
actin is an ______ that is helical in structure (two chains wrapped around each other)
ATPase
actin is roughly ______ in diameter
7 nm
actin is ______ if not stabilized; can undergo rapid bouts of assembly and disassembly
highly dynamic
actin has a huge array of ________ regulated by ________
configurations, accessory proteins
microfilaments act as substrate for members of the ______ family of motor proteins to move along and carry cargo
myosin
unlike microtubules, actin filaments do _____ have specific organizing centers like centrosome and can be nucleated _______ in the cell
not, almost anywhere
actin filaments are polarized filaments with a barbed and pointed end where the _______ end favors assembly and the ______ end does not
barbed, pointed
myosin motors read the polarity of microfilaments and move from one end to the other but most move towards the _____ end
barbed
microfilaments functions include concentration in the cell cortex for various functions, cleavage furrow ______ during mitosis, cell ______ , organelle _______, and contractility
pinching, motility, transport
_________ is an accessory protein often bound to the structure of actin filaments
tropomyosin
there are three actin isoforms which include ____, _____, and ______
alpha, beta, gamma
_____ actin is muscle specific where _____ and ____ are found in most cells
alpha, beta, gamma
actin must be _____ loaded for nucleation and polymerization
ATP
nucleation promoting factors (NPF) activate the __________ which regulates actin nucleation by adding actin monomers to produce _______ actin filaments
Arp2/3 complex, branched
spire is a protein that ______ actin on the ______ end and helps initiate the _______ of actin and protects from disassembly
nucleates, pointed, assembly
formins are a protein that ______ existing actin on the ______ end and helps initiate the _______ of actin elongation
nucleates, barbed, assembly
monomer sequestering is when a actin monomer is bound to ______ and cannot be used until the protein is _____
depolymerizing protein, removed
capping is when a cap is placed on ______ end of actin and stops ________ to make short capped filaments
barbed, polymerization
cross linking is when _______ actin filaments or ______ filaments, create _________ or _______ that have structural functions and other functions within cytoplasm
short capped , long , bundles, networks
annealing is when ________ actin filaments are joined together to make a ______ filament
short uncapped , long
in fibroblasts the actin cytoskeleton is organized into stress fibers which are composed of ______, _______ and _______ where the function is mainly in _______
myosin, alpha actin, formins, contractility
the leading edge meshworks of fibroblasts are composed of ______ at the edge of the cells that are formed and controlled by ________, ______ and _______
actin filaments, Arp2/3 complex, profilin, cofilin
the sarcomere is composed of actin filaments that overlap with their ______ on the outside and _______ on the inside
pointed ends, barbed ends
myosins and f-actin are associated with force by generating mechanoenzymes with roles in _______ and intracellular _______ that allows ______ to contract
contractility, transport, sarcomeres
myosin I and myosin v contain ______ light chains that are phosphorylated once ______ is present binds
calmodulin, calcium
myosin II contains an ______ and ______ light chain
essential, regulatory
the _______ light chain of myosin II acts as an off/on switch
for muscle contractions by controlling the accessibility of myosin ______ which is controlled by ______
regulatory, heads, kinases
the essential light chain of myosin II is vital in proper ______ of the myosin motor protein
function
_____ is the main movement myosin in all muscles
myosin II
during cytokinesis _____ and ______ are located at the contractile ring (cleavage furrow) during cell division and pinches off cells,______ is located at the poles
F actin, myosin II, myosin I
_______ are actin based epithelial projections where in the small intestines they increase surface area for absorption
microvilli
The _____ end of the actin filaments are located at the tip of the microvilli
barbed
in the ear cells ______ detect sound waves
sterocilia
The ______ domain of lateral arms binds to the membrane in microvilli where the arms are made of ______ and ______
hydrophobic , calmodulin, myosin I
the lateral arms in microvilli attach to _____ filaments, that make up the structure, and stabilizes the filaments by binding to the ______
actin, membrane
______ and ______ stabilize the array of microfilaments in the microvilli
Villin, fimbrin
the physical link between the cytoskeleton and the extracellular environment provides ___
Mechanical continuity
F actin serves as scaffolding for spectrin web in the ______ cytoskeleton
red blood cell
hereditary spherocytosis is an actin malfunction disease which deforms ______ to fragile spherocytes because of weakened _______of spectrin to band 4.1
red blood cells, binding affinity
hereditary elliptocytosis is an actin malfunction disease that deforms red blood cells into fragile elliptocytes because of _______ of spectrin
incomplete formation
breast cancer, in some forms the actin associated protein_____, which links integrin receptors to the actin cytoskeleton, is disrupted promoting _____ migration of cancer cells
tensin, metastatic
familial hypertrophic cardiomyopathy is caused by a specific mutation in _____
cardiac actin
mutations in skeletal muscle actin are associated with _________ characterized by the structural abnormalities of the muscle and variable degrees of muscle ______
congenital myopathies, weakness
myosin VI mutations cause _____ due to improper formation of _______
deafness, stereocilia
myosin VII mutations are associated with deafness, ________, and ______ (usher syndrome type 1)
neurological disorder, blindness
phalloidin is a type of toxin from mushrooms that binds to and stabilizes _______
actin filaments
bacteria pathogens use the cytoskeletal elements by developing ________ to help move around bacterium
actin-Nucleation-like proteins
intermediate filaments are ______ and are comparatively _______ (much more stable)
non-polarized, non-dynamic
intermediate filaments fill spaces within cells, give cells tensile _____, and are important at cell _____
strength, junctions
intermediate filaments are _______ across cell types and different cell types have different kinds of intermediate filaments
much less conserved
______ filaments can be used as cell specific markers
intermediate
intermediate filaments form when two monomers form a parallel ________, then two ______ form a antiparallel tetramer which interact in a staggered array and continue to stack in an array of ________, the filament then lengthens and winds into a ______ like structure
coiled-coil dimer, dimers, 8 tetramers, rope
type I _______ and type II _______ intermediate filaments are found in ________ and ______ derivatives (hair, nails etc)
acid keratin, basic/neutral keratin, epithelial cells, epidermal
type III _______, _______, and _______ intermediate filaments are found in cells of mesenchymal origin (fibroblasts), muscle cells and glial cells respectively
vimentin, desmin, glial fibrilry acidic protein
type IV neurofilament protein intermediate filaments are found in ______
neurons
type V nuclear lamins A, B, and C intermediate filaments are found in the ______
nuclear lamina of all nucleated cells
epidermolysis bullosa simplex is caused by a mutation in ______ genes expressed in basal cell layer of _____, results in a skin that is very sensitive to mechanical injury
keratin, epidermis
progeria is a fast aging disease associated with a mutation in _____ protein
nuclear lamina
desmins are mutated in ______
cardiomyopathies
keratins are mutated in greater than ____ diseases
20
neurofilament proteins are linked to small subunit mutation in the IF/2E forms of _______
Charcot-Marie tooth disease
peripherin is induced after ______
peripheral nerve injury
Glial fibrillary acidic protein is mutated in Alexander disease a leukodystrophy, which results in abnormal _____
myelin
