Cytoskeleton Flashcards
Components of the Cytoskeleton
Actin filaments, microtubules, intermediate
filaments
provide rigidity and structural stability to cells
Intermediate Filaments
serve as part of a transport system in the cell and help to position organelles in the cell
Microtubules
transport cargo throughout the cell through interaction with microtubules
Motor proteins
A dense network of protein polymers that controls the shape and biochemical activity in the cell
cytoskeleton
Structure of Intermediate Filaments
string and rope-like
Intermediate Filaments form a strong durable network in the cytoplasm of the cell (T or F)
True
A mutant from of keratin (an intermediate filament) makes skin blister easily (T or F)
True
What do intermediate filaments do to the nuclear envelope?
support and strengthen it
Microtubules grow out from what?
an organizing center
Structure of Microtubules
hollow tubes made up of tubulin subunits
Tubulin polymerizes from nucleation sites on a centrosome (T or F)
True
What does GTP hydrolysis control?
the dynamic instability of mircotubules
Microtubules guide the transport of molecules and molecular complexes in the nerve axon (T or F)
True
What two molecular motors move along mircotubules?
kinesins and dyneins
The same motor protein transports different types of cargo along the microtubules (T or F)
False, different motor proteins
Structure of Actin Filaments
thin, flexible protein threads
Actin filaments allow animal cells to do what?
take on many shapes and have many functions
What decreases the stability of the actin polymer?
ATP hydrolysis
In what component of the cytoskeleton does treadmilling occur?
actin filaments
In what component of the cytoskeleton does dynamic instability occur?
microtubules
Describe Treadmilling
Actins are being added to the plus end while actins fall off the minus end
Describe Dynamic Instability
There is a GTP cap on plus end. GTP-tubulin is added to plus end causing the cap to be lost. The GDP-tubulin is all lost falling off the plus end. Once small, the GTP cap is reestablished.
control the action of actin filaments in vertebrate cells
actin-binding proteins
Forces generated by actin filaments in the cortex of the cell help move cell forward (T or F)
True
What pushes the leading edge of a lampellipodium forward?
a web of polymerizing actin filaments
a motor protein that functions with actin filaments
Myosin-I
Myosin-II molecules can associate with one another to form myosin-II filaments (T or F)
True
Bipolar myosin-II filaments can’t slide two actin filaments past each other (T or F)
False, they can
How do muscles contract?
a sliding-filament mechanism
