Cytoskeleton Flashcards
what colors do microtubules, microfilaments and intermediate filaments show on fluorescent staining
microtubules- green
microfilament/actin - red
intermediate filaments - blue
which is the largest
a) actin filaments
b) microtubules
c) intermediate filaments
microtubules
is the cytoskeleton larger in prokaryotes or eukaryotes
eukaryotes
is the cytoskeleton static or dynamic
dynamic
what are intermediate filaments composed of
fibrous protein
which cytoskeleton structure is a rope-like fiber
intermediate filament
which cytoskeleton structure forms a meshwork structure
intermediate filaments
what is a desmosome
cell structure specialized for cell-to-cell adhesion
what are the intermediate filaments in the nucleus
nuclear lamins
what are the intermediate filaments in epithelial cells
keratin filaments
what are the intermediate filaments in the connective tissue, muscle cells, and glial cells
vimentin and vimentin related filaments
nuclear lamins are only located in a few animal cells. true or false
false. they are located in all animal cells
what intermediate filaments are in nerve cells
neurofilaments
what is Epidermolysis bullosa simple
A genetic disease, keratin gene mutation. A mutant form of keratin makes skin more prone to blistering
what aids in the bundling of intermediate filaments and links these filaments to other cytoskeletal protein networks
plectin
what does plectin mutation cause
a combination of; Epidermolysis bullosa simple muscular dsytrophy and neurodegenaration
what happened to mice lacking plectin gene
died within a few days due to abnormal heart muscles
what do defects in nuclear lamins cause
cause a rare class of premature aging disorders called progeria i.e. the nucleus loses its shape
what is the major microtubule organizing centre in animal cells
the centrosome
what drives the dynamic instability of microtubules
GTP hydrolysis
drugs cannot modify dynamic instability of microtubules true or false.
false. they can
what do microtubules help motor proteins do
drive intracellular transport
what does dynein do
They convert the chemical energy stored in ATP to mechanical work. Dynein transports various cellular cargos, provides forces and displacements important in mitosis, and drives the beat of eukaryotic cilia and flagella
where do microtubules grow from at their plus ends
gamma tubulin
microtubules grow independently of their neighbors. true or false
true
what is selective stabilization of microtubules
where the length of some microtubules are maintained and others arent
what do capping proteins do
control access to the free barbed ends of actin filaments and is therefore a major factor affecting actin filament elongation
what does selective stabilization do to a cell
polarize it
how does GTP hydrolysis control stabilization
by GTP binding to tubulin dimer causing more addition of GTP-tubulin
what causes shrinking of the microtubule
GDP binding to the tubulin dimer
what drug binds and stabilizes microtubules
taxol (treat breast and ovarian cancers)
what is the effect of colchicine and colcemid
binds tubulin dimers and prevents their polymerization
what drugs have the same effect as colchicine, colcemid
vinblastine and vincristine (childhood hematologic malignancies)
what drug prevents cell division during mitosis
colchicine (for gout)
most differentiated cells are polarized. what does this mean
one end of the cell is structurally and functionally different from the other
true or false, organelles travel slower by diffusion than by microtubules
false. it can take years for their diffusion whereas in microtubules it takes seconds
what are the two families of motor proteins
dynein and kinesin
what do motor proteins do
move vesicles along microtubules
how do dynein and kinesin move along the microtubules
using their globular heads
what directions do dynein and kinesin move
dynein moves towards the minus end and kinesin moves towards the plus end
what determines the cargo type when moving along the microtubule
depends on the tail of the dynein or kinesin
what are the repetitive movements cilia makes
power stroke and recovery stroke
how are microtubules in cilium and flagella arranged
9+2
what causes the flagella with dynein to bend
linking protein
what does dynein do in an isolated doublet microtubule
producing microtubule sliding with help of ATP
what does cell crawling depend on
cortical actin
what decreases stability of the actin filament
ATP hydrolysis
how do actin filaments regulate filament length
Treadmilling
what does phalloidin (drug) do
binds and stabilizes filaments
which drug caps plus end and prevents polymerization in actin filaments
cytochalasin
what does latrunculin (drug) do
binds actin monomers and prevents polymerization
what are types of actin binding proteins (name 6)
myosin motor protein side-binding protein cross linking protein (cortex) severing protein nucleating protein bundling protein (filopodia)
what proteins regulate filament formation
thymosine and profilin (prevent their polymerization)
what protein promote polymerization of actin filaments
formin
what help move a cell forward
Forces generated in the actin-filament-rich cortex
which direction does myosin I move across the microtubule
from negative to positive ends
what has a dramatic effect on the organization of actin
filaments in fibroblasts
Activation of Rho family GTPases
name two regulators in actin dynamics
Rac and cdc42
what triggers muscle contraction
Ca ion increase
what is the bare region
where the heads and tails of myosin meet (confirm this)
what defines the boundaries of the sarcomere
Z-disc
what surrounds the myofibrils
T tubules and the sarcoplasmic reticulum
what controls skeletal muscle contraction
troponin and tropomyosin (blocks myosin binding sites) complexes
what does Ca do in muscle contraction
exposes myosin binding site
what is an example of a capping protein
gelsolin, which prevent polymerization of the filament
what are the three classes of actin
α-actin of muscle, β-actin, and γ-actin of non-muscle cells.
what proteins other than myosin bind to actin to perform essential cellular functions
α-actinin, spectrin, fimbrin, filamin, gelsolin, and talin
what are the three types of association in actin filaments
Contractile bundles
Gel-like networks
Parallel bundles
what types of association in actin usually has myosin
Contractile bundles
what structure maintains focal contacts of the cell with extracellular matrix
actin filaments
what is the relationship between integrin, talin, vinculin, fibronectin and the actin filaments
integrin (a transmembrane protein) binding to fibronectin and talin, which contacts both vinculin and the actin filament
what is the function of gel-like connection
provide the structural foundation of much of the cell cortex
what provides stiffness in gel-like networks
protein filamin
what are fimbrin and villin responsible for
forming actin filaments into closely packed parallel bundles that form the core of microspikes and microvilli, respectively
what does spectrin do
assists in structural integrity of cortex
where are bundles of actin filaments anchored
terminal web
what structures anchor the nucleus
intermediate filaments
how many tetramers form an intermediate filament
8
what is the head and the tail of each monomer called
N-terminus (head) and C-terminus (tail)
what is the central domain composed of
elongated alpha helix
what type of isoforms are keratin fibers
family of acidic and basic isoforms
what is Epidermolysis bullosa simplex (EBS) characterized by
skin blisters after minor trauma (keratin 5 and 14 mutant genes)
what conditions leads to excessive keratinization of the epidermis
Epidermolytic hyperkeratosis (EH) ((mutations of keratin 1 and 10 genes)
fragmentation of the epidermis of the palms and soles is caused by what disease
Epidermolytic plantopalmar keratoderma (EPPK) (keratin 9 mutation)
what is most common intermediate filament protein
vimentin
what is vimentin derived from
mesenchyme
what binds keratin filaments into bundles
flaggrin
what do Synemin and plectin bind
desmin and vimentin, respectively
what do plakins assist in
assist the maintenance of contact between the keratin intermediate filaments and hemidesmosomes of epithelial cells as well as actin filaments with neurofilaments of sensory neurons
describe centriole structure
composed of nine highly organized microtubule triplets.
which of the following do microtubules not do
a) axoplasmic transport in neurons
b) melanin transport in pigment cells
c) movement of RNA along the nucleus
d) vesicle movements among different cell compartments
c
what are the main side effects of taxol
neurotoxicity and suppression of hematopoiesis (production of all of the cellular components of blood and blood plasma)
what is Kartagener’s syndrome
autosomal recessive ciliary dyskinesia frequently associated with bronchiectasis and sterility in men
what is Kartagener’s syndrome a result of
structural abnormalities in the axoneme (defective or absent dynein) that prevent mucociliary clearance in the airways (leading to persistent infections) and reduce sperm motility and ovarium transport in the oviduct (leading to sterility)
where are the microtubules not dynamic
axonemes
what are the monomeric proteins in intermediate filaments
alpha helical rod like protein
what is the overall structure of intermediate filaments
cable of 4 intertwined protofibrils, each consisting of bundled tetramers associated end to end
