Lecture 5 Cytoskeleton Flashcards
What are the three “cytoskeletons”?
microtubules, microfilaments, and intermediate filaments
Microtubules are made of ____ while microfilaments are made of _____
tubulin
actin
Microtubules are often found in ____
golgi
What are functions of the cytoskeleton? (3)
Maintain cell shape
stabilize cell adhesion and placement
facilitate movement
Microtubules bind GTP at the _ (+/-) end, which promotes _____
+
polymerization
_____ have GDP at their minus end, which favors dissociation.
Microtubules
The minus end of a microtubule can embed in a ____, which is positioned near the nucleus
centrosome
_____ create intracellular highways, providing transport for organelles and axons.
Microtubules
____ act as motor proteins and move an organelle to the PLUS end of the microtubule
Kinesins
Dyneins move organelles toward the _ end of a microtubule
minus
Dynesis and Kinesin are examples of ____ associated proteins and are involved in signal transduction as____
microtubule
kinases
Blockading the movement of MTOC’s towards poles during prophase is a target of ____
chemotherapy
Cilia are made up of ____
microtubules
Microfilaments consist of _____ filaments and require _____ to polymerize
actin
ATP
Microfilaments are _____ stable than microtubules
more
_____ is when there is turnover of microfilaments without change in size.
Treadmilling
Actins stabilize ____ adhesions in stress fibers
integrin
____ belts consist of circumferential actin near apical cell surface
adhesion
Actin stabilizes ____-mediated adherens junctions and is organized by _____
cadherin
catenin
______ is an outward projection of the cytoplasm in the leading edge of migrating cells that is made of actin
lamellapoida
The cleavage furrow is an invagination of cell surface during cytokinesis that is organized by the ______ cytoskeleton
actin
Microvilli are fingerlike extensions at the cell surface made of ____ filaments
actin
____ is a mushroom poison that binds F-actin and prevents disassembly at the minus end
Phalloidin.
Cytochalasins are alkaloid fungal toxins that bind to the ____ of actin and block polymerization
plus
Latrunculins bind ____ and induce depolymerization
G-actin
_____ creates a membrane skeleton and is most common in erythrocytes. Sickle cell anemia is caused by a modification of it
Spectrin
______ _____ are very stable, with assembly and disassembly being regulated by protein phosphorylation
intermediate filaments
Type _ intermediate filaments are acid keratins. Type _ are neutral to basic keratins
1, 2
Change in _____ expression is among the most common markers of neoplasia
cytokeratins (ie, type 1 and 2 IFs)
Vimentin and Desmin are examples of type 3 ____ _____’s
intermediate filaments
_____ is a type 3 IF used as a marker of dedifferentiation of invasive carcinomas
Vimentin
_____ is found in skeletal muscle at the Z-disk.
Desmin
Type __ intermediate filaments are neurofilaments; common in axons and dendrites
4
Intermediate filaments are ropelike fibers of _____, _____, or ______
keratins
lamins
vimentin
A _______ is a vertical linear array of alpha/beta tubulin dimbers
protofilament
_ protofilaments associate to form a tubule in microtubules
13
Taxol is an anti-cancer drug that binds to ____, preventing their depolymerization
mictrotubules
Actin bundles along basal cell surfaces terminate at ____ adhesions
focal
Actin is organized by _-actinin and _____ in stress fibers
alpha, talin
Hereditary spherocytosis is due to mutant _____
spectrin
alpha-______ is a type 4 neurofilament found in the spinal chord
internexin
