Test 2: Lecture 42 and 43 Flashcards
movements of the cell
Actin cytoskeleton and motors
movements inside the cell
Microtubule cytoskeleton and motors
structural support
Intermediate filaments
three types of cytoskeletal fibers
actin filaments
microtubules
intermediate filaments
actin filaments
Form stress fibers and cortical network of thin filaments in most cell types
Are the major component of muscle fibers
Mediate all types of motile and contractile behavior of cells
microtubules
- A highly dynamic radial network of fibers
- Mediate intracellular transport (vesicles move on microtubules)
- Coordinate global cellular events, such as polarization and division
Intermediate filaments
- A rigorous network of fibers that follows the microtubule cytoskeleton
- Assist in cell shape maintenance and provide support for anchoring intracellular structures
___ coordinate global cellular events, such as polarization and division
microtubules
___ mediate all types of motile and contractile behavior of cells
actin filaments
___ assist in cell shape maintenance and provide support for anchoring intracellular structures
intermediate filaments
sizes of cytoskeletal fibers
actin: 7 nm
intermediate filaments: 10 nm (keratin)
microtubules: 20 nm (hollow tubes)
Actin has both generalized and ___ cellular roles
specialized
some roles of actin
Cell structure
Cytokinesis
Adhesion - keep epithelial cells toegther
Contractility - how cells divide
Cell motility - (fibroblast- actin moves/ walks cell)
Local organelle transport- act like railroad similar to microtubules
3 type of structures formed by actin in non muscle cells
stress fibers
cell cortex
filopodium
cell cortex of a fibroblast has ___
actin in random criss crossed directions
filopodium in fibroblast have actin in ___
tight parallel bundles
stress fibers in fibroblast have actin in ___
antiparallel contractile bundles
how does actin move cell
leading edge (lamellipodium)- actin polymerization extends plasma membrane
Myosin II contracts the back
little feet contain integrins
___ form muscle tissues in the
body (including striated
skeletal muscle,___ muscle, and
cardiac muscle)
myocytes
smooth
____ respond to nerve stimuli to produce mechanical force by contraction.
myocytes
what is special about cardiac muscle
striated
contract spontaneously by internal pacemaker
myocytes are the driving force for body movement and normal functioning of many organs, including ___, ___, and digestive system
heart
blood vessels
actin filaments
minus (pointed end/slow growing)
plus end (barbed end/ fast growing)
actin filaments interact with different actin-binding proteins to perform different functions such as ___
actin attaches ___, errors in this leads to ___
the cell membrane and into the extracellular matrix
metastasis of cancer cells (not held on tightly and break off and travel outside of tumor and infect other areas)
cells can change direction quickly by
breaking down and reforming actin in a new part of the cell
Dynamic changes in cellular actin allow cells to respond quickly to their environment, for example, during ___.
chemotaxis
Defects in cell adhesion and signaling can lead to ____
polycystic kidney disease
defects in actin structure can lead to ___
heart failure
Actin-based motility in bacterial ___
pathogenesis
bacteria get comet tails that can use actin filaments inside cell to move around cell quickly
three formations of myosin
muscle cells: bunch of myosin wrapped around each other with heads on outside, tails in center
non muscle: myosin tails attached to vesicle and walk down actin carrying vesicle
small muscle formation, 4 instead of a bunch
myosin is a ___
mechanochemical ATPases
used phosphorylation of ATP to ADP to create movement
Power stroke
what is a power stroke
how myosin walks down actin
Myosin converts ATP energy to produce power strokes along actin filaments
ATP attached to myosin
phosphorylated into ADP
causes movement of myosin (walks down actin)
Actin form ___ in non-muscle cells and ___ in muscle cells
cortex and stress fibers
myofibrils
actin mediate ___ and ___ by interacting with myosin motors
cell movement
muscle contraction
___ mediate cell adhesion
actin
actin mediate specialized types of local ___
organelle movement
actin form ___ during division in animal cells to separate two daughter cells
contractile ring
Microtubules mediate ___ transport
intracellular
rail road inside cells
in interphase cells- non dividing cells
4 common arrays of microtubules
in interphase cells microtubules grow from the ___
centrosome in a radial form
ciliated cells microtubule formation
dividing cells microtubule array
microtubules are made of __
alpha and beta tubulin
hollow cylinders
polar, dynamic polymers
plus and minus end
20-25 nm constant width but variable length
plus end will gain length, while minus end will lose length
most minus ends of microtubules are anchored at the ___, will add subunits to the ___ end toward the ___ of the cell
centrosome (near center of cell)
plus
outside
minus end of microtubules are in the center of the cell? true or false
true
minus end anchored at centrosome in center of cell
plus ends at outer part of cell, grow outward
true or false. plus end of microtubules are in the center of a cell
false, negative end in the center, plus end on the outside
microtubules grow from the __ end to the __ end
minus
plus
Microtubules mediate ___ over large distances
fast organelle transport
vesicle with bound ___ move from + to - end of microtubules
dynein
vesicle with bound ___ move from - to + end of microtubules
kinesin
During mitosis, microtubules reorganize to form ___ and segregate chromosomes into two daughter cells
mitotic spindle
microtubule drugs that favor depolymerized state
colchicine
colcemid
vinblastine
vincristine
prevent microtubules from polymerizing and depolymerizing- stops dividing but also prevents movement of organelles, can be very toxic for cell
microtubule drugs that favor polymerized state
taxol
prevent microtubules from depolymerizing stops dividing
but still allows movement of organelles, less toxic
some drugs use to treat aggressive cancers
microtubule drugs
attach to depolymerized or polymerized state
both stop cell from dividing, but drug that is attached to depolymerized state prevents organelles from moving which can be very toxic for cell
taxol
microtubule drug that favors polymerized state
two types of motors for microtubules
dynein
kinesin
dynein
motor for microtubule
always moved + to - (outside to inside of cell)
Drives organelle transport, microtubule array
formation and maintenance
- Drives spindle movements during mitosis
- Drives movement of cilia and flagella that can propel the movement of certain cell types
kinesin
motor of microtubules
moves - to + (inside to outside of cell)
(some can go opposite during mitosis)
Drives organelle transport
• Drives spindle and chromosome movements during mitosis
Kinesin and dynein have opposite ___ on microtubules
polarity
Microtubule motors, like myosin, move by converting ATP energy into ___
mechanical force
myosin
Motor on actin
Drives muscle contraction
Drives local organelle movement over short distances
Drives cell motility together with actin polymerization
___ are specialized non-centrosomal microtubule array that are driven by dynein to propel the movement of certain cells
Cilia and flagella:
how does dynein make cilia and flagella work
9 +2 formation of microtubules
dynein holds two microtubules together, during power stroke the microtubules are stuck together, bend instead of move,
the bending from side to side cause movement
immotile cilia syndrome
primary ciliary dyskinesia
Caused by dynein mutation
Diagnosed in humans, dogs, pigs, and
cows.
Phenotype: all cilia are immotile
• Immotile sperm - male infertility
• Immotile cilia in the respiratory tract
– respiratory disorders
dynein mutation
Immotile Cilia Syndrome
male infertility and respiratory disorders
(Primary Ciliary Dyskinesia)
microtubules form ___ in interphase cells that support cell polarization and intracellular organelle transport
radial arrays
microtubules reorganize in mitosis to ___ equally to two daughter cells
segregate chromosomes
microtubules mediate ___ over long distances
rapid organelle transport
microtubules support the movement of cilia and ___
flagella
Microtubule motors ___ move along microtubules in opposite directions
kinesin and dynein
two types of intermediate filaments
cytoplasmic
nuclear
types of cytoplasmic intermediate filaments
keratin
vimentin and vimentin related
neurofilaments
type of nuclear intermediate filaments
nuclear lamins
envelope around nucleus
keratin is found in
epithelia
vimentin and vimentin related intermediate filaments are found in ___
connective tissue, muscle cells and neuroglial cells
nuclear lamins are intermediate filaments found in __
all animal cells
envelope around the nucleus
intermediate filaments can form __ structure
flexible rope like structures
Intermediate filaments support the structure of cells and tissues by
form sheets that stretch in between cells and keep them connected to each other
Epidermolysis Bullosa Simplex
C ells that express mutant keratins rupture
in response to mechanical stress.
disorder of intermediate filaments
epidermis and dermis detach from each other
Diagnosed in both humans and dogs.
