Test Four Cytoskeleton Flashcards
What is a cytoskeleton
Network of protein filaments throughout cytoplasm
Cytoskeleton supports
The movement of organelles and vesicles
What are the types of protein filaments
Intermediate filaments, microtubules, actin filaments
Subunit of intermediate filaments
Fibrous proteins
Function of intermediate filaments
Provide cellular strength when stretched
Location of intermediate filaments
From nucleus to plasma membrane and connected by desmosomes
Example of intermediate filament
Nuclear lamina
What is nuclear lamina
Intermediate filament around nucleus to provide strength to nuclear strength
Structure of intermediate filament
Strong and rope like elongated fibrous proteins
Diameter of intermediate filaments
10 no
Monomer of intermediate filaments
Strands have globular head and tail with a helix in the middle
Dimer of intermediate filament
Coiled coils
Tetramer of intermediate filament
Two coiled coils bound by noncovalent forces
Location of intermediate filaments
Muscle cells, epithelial cell, along nerve axons for reinforcement and for protection
What are the four classes of intermediate filaments
Keratin, vimentin and vimentin-related filaments, neurofilaments, and nuclear lamina
Where are keratin filaments found
Epithelial cells
Where are vimentin filaments found
CT, muscles and neuroglia cells
Where are neurofilaments found
Neurons
Nuclear lamina filaments are found where
All cells
Example of keratin
Hair, nails, skin, claws, hooves, feathers, lining of gut
Location of keratin
Stretch through cell to desmosome
What are the accessory proteins that stabilize intermediate filaments
Plectin
Function of plectin
Links intermediate filaments to microtubules and then to desmosomes
What are some problems with intermediate filaments
Epidermolysis bullosa simplex
Example of mutations in plectin
Bullosa simplex, muscularis dystrophy, and neurodegeneration
Nuclear lamins disassemble when
Mitosis occurs
Nuclear lamins are phosphorylated by
Kinases
Example of problems with lamins
Progeria
What is progeria
Prevents cells from dividing, causes children to look old
Subunit of microtubules
Tubulin
Function of microtubules
Organizing chromosomes, moving organelles, involved with motor proteins, infrastructure of cell
Microtubules grow out of
Centrosome
Microtubules are a dimer of
Alpha and beta tubulin
What are protofilaments
Long strand of dimer microtubules
Microfilaments contain
13 protofilaments together in a hollow tube
Microfilaments have specific
Polarity, beta end with positive and alpha end with negative
What side of dimer microfilament adds to elongate
Positive end (beta)
What bond is between alpha and beta part of microtubule
Covalent bond
What bond is used to put a lot of microtubules together
Non covalent
Centrosomes are located where
Near nucleus
Centrosome is made of
Gamma tubulin in a ring that forms sphere
What in centrosome grows microtubules
MTOC’s
Function of MTOCs
Control number, orientation and location of microtubules
Centrioles are found
Inside centrosomes
Function of centrioles
Unknown
Centrioles made up of
Cylinder of short microtubules
Microtubules are in constant
Dynamic instability (changing)
What is needed to attach dimer of microtubules
GTP
GDP is microtubules causes
Shrinkage of tubules
Dimers of microtubules with GTP or GDP pack more tightly
GTP
What does GTP cap do in microtubules
When microtubule dimers are added too quickly for GTP hydrolysis and will keep growing
What causes disassembly of microtubules
GTP hydrolysis into GDP
What drug causes no microtubule assembly by binding to tubulin in cytoplasm
Colchicine
What drug causes microtubules to never disassemble by binding to microtubules
Taxol
What are the two cancer drugs that affect microtubule growth and disassembly
Taxol and colchicine
What protein that is associated with another cell structure and cause microtubule to stop assembling
Capping protein
Specialized microtubule cells have less
Dynamic instability
Specialized microtubule differentiated cells are usually
Polarized
Salvatore movement is normally
Directional and steady
Motor proteins bind to
Actin filaments or microtubules
How do motor proteins travel
By ATP hydrolysis
Motor proteins bind to other cells components such as
Vesicle or organelle to move them
What are the two families of motor proteins
Kinesins and Dyneins
Kinesins move
Away from centrosome
Dyneins move
Toward centrosome
Motor proteins contain
Globular ATP binding heads and cargo binding tails
What of motor protein walks along microtubules
ATP hydrolyzing head
What pulls and stretches ER membrane along microtubules
Kinesins
What pull golgi toward the centrosome along microtubules
Dyneins
Microtubules move what organelles
Golgi and ER
Cilia are
Hair like structures
What moves cilia
Dynein
What anchors cilia
Basal body
Cilia have what in their core
Microtubules covered by plasma membrane
Movement of cilia
Power stroke then recovery stroke
Function of cilia
Propel a cell through fluid, move fluid over cell surface, collecting food, moving mucus, moving eggs
Structure of flagella compare to cilia
Longer
Function of flagella
Motility
Structure of cilia and flagella
9 doublet microtubules in a ring around two microtubules
Movement of cilia and flagella
Core bends with help of accessory proteins
What motor protein helps cilia and flagella walk
Ciliary dyneins
Subunit of actin filaments
Actin
Function of actin filaments
Affects movement of cell surface, phagocytosis, cell division, crawling, muscle contraction
Location of actin filaments
Under plasma membrane
Structure of actin filaments
Short, globular actin molecules in a chain with polarity , thin and flexible
Actin monomers add or subtract from what end
Either
What is bound to actin monomers
ATP
What promotes disassembly in actin filaments
ATP hydrolysis
What drug prevents actin formation by binding to loose actin
Cytochalasins
What drug prevents actin disassembly by binding to actin filament
Jasplakinolides
What prevents actin monomers from polymerizing out of control
Thymosin and profilin
What other proteins control actin activity
Actin-bundling proteins, cross linking, filament severing proteins (gelsolin)
Example of actin
RBC
Cell cortex of actin filaments
Concentrated network of actin filaments linked by actin-binding proteins
The cell cortex of actin filaments provides what function
Mechanical strength and structural support
How do actin filaments in cells crawl
Protrusion from front grabs cytoplasm, adhesion from protrusion anchors and rest of cell drags forward
What is the protrusion caused by actin polymerization
Lamellipodia
What in actin is the stabilizing cell, anchor
Integrins
What are the exploration protrusions of actin filaments
Filapodia
What helps to form branched actin
Actin related proteins (ARPs)
How do ARPs work
Assembly at front and disassembly at back
What protein interacts with actin filaments to create movement of cell or muscle contraction
Myosin
What are myosin
Actin dependent motor proteins
Myosin 1 is for
Cellular movement
Myosin 2 is for
Muscle movement
How does myosin 1 work
One Globular head interacts with ATP and tail determines and grabs cargo
What in actin filaments help actin cytoskeleton movement
Receptor proteins
What protein changes organization of actin
Rho
What Rho protein in actin causes filopodia formation
Cdc42
What Rho protein in actin causes lamellipodia formation
Rac
Do all types of muscle use actin and myosin
Yes
Describe myosin 2
2 ATPase head and tail (coiled coil)
What on myosin creates the filament
Tails
What is a muscle fiber
Numerous cells fused into one long cell
Myofibrils mainly consist of
Sarcomere
What is the contractile element of muscle cell
Myofibrils
What makes up a sarcomere
Action and myosin 2 with Z disc
What is the regulator of tropomyosin
Troponin
What is rigor Mortis
No more ATP being produced, muscle is in constant contraction and stiffens
What are the energy requirements for skeletal muscle
ATP for myosin head, ATP for Ca2+ pump into the SR, ATP for Na/K pump to resort resting membrane potential in cell
Sources of energy in skeletal muscle
ATP stores, phosphocreatine, glycogen stores and oxidative phosphorylation
ATP stores last for
1 to 2 seconds
Phosphocreatine source of energy lasts for
5 to 8 seconds
Glycogen stores for energy last for
One minute
Oxidative phosphorylation for source of energy lasts
Indefinitely
The greater the number of cross bridges form the stronger
The generated force
What is isometric contraction
Increase in tension, no decrease in length of sarcomere
What is isotonic contraction
Decrease length of sarcomere and constant tension generated
What is eccentric concentration
Muscle is lengthening and joint is extending
What is concentration contraction
Muscle is shortening and joint is flexing
Describe fast twitch
Larger fibers, lower blood supply, fewer mitochondria, and extensive ER
Describe slow twitch
Smaller fibers, greater blood supply, many mitochondria, and myoglobin
What is a motor unit
One motor neuron and all of the muscle cells innervated by it
What is motor unit summation
Recruitment of motor units determines amount of force generated by muscle
What causes muscle to sustain its contraction
Rapid stimulation by motor neurons
Sustained contraction is called
Tetanus
What is treppe
Muscle will be weaker than a warmed up muscle k
Hypertrophy of muscle includes
Increase in number of myofibrils (diameter) and increase in number of sarcomere (length)
Atrophy includes
Denervation atrophy and disuse atrophy (loss of use)