Cytoskeleton Flashcards
Do prokaryotic and eukaryotic cells have the following?
Cytoskeleton, intracellular movement
Prokaryotic cells have none
Eukaryotic have both
what is the cytoskeleton?
The network of protein filaments that provides structural framework also plays a role in cell movement and mitosis
How is the cytoskeleton dynamic?
Can dismantle in one spot and reassemble in another to change cell shape
what structure organizes the cytoplasm?
Cytoskeleton
Which of the following play a role in signalling?
Microfilaments, Microtubules, Intermediate filaments
All
What are the subunits of Microfilaments and microtubules
Microfilaments: Actin
Microtubules: ab-tubulin dimers
What is the diameter, structure and function of the following:
microfilaments
intermediate filaments
microtubules
Microfilaments: 7-9 nm, double helix, maintain cellular shape
Intermediate filaments: 10 nm, two anti-parallel helices/dimers (tetramers), maintain internal tridimensional structure of the cell
Microtubules: 25 nm, polymer of tubulin subunits, intracellular transport, alpha and beta tubulin
Are the filaments (microtubules included) permanent structures?
No they are dynamic.
What is G-actin and F-actin
G-actin are the subunits that come together to form microfilaments
G-actin polymerizes to form F-actin
Are microtubules and microfilaments polar or non-polar?
Polar
which end of microfilaments grow faster
the plus end
Where are actin filaments nucleated?
nucleated at the plasma membrane
What is the strongest filament
intermediate filament
what are the four classes of intermediate filaments? where are they found?
Cytoplasmic: Keratins (epithelial cells), Vimentins (in connective tissue, muscle cells and glial cells), Neurofilaments (nerve cells)
Nuclear: Nuclear lamins (all animal cells)
what role does microtubules play in mitosis?
mitotic spindle
How do microtubules affect kinesin and dynein?
controls directionality
What is taxol?
Anticancer drug which stops mitosis
Which polarized end are subunits added to in microtubules?
Plus end
How many protofilaments are in a tubulin monomer
13 laterally associated protofilaments
which direction does kinesin and dyneins move on a microtubules?
Kinesins towards the plus end
Dynein towards the negative end
what are the 3 types of junctions
anchoring, tight, gap
adhesiveness of cadherin depends on what
Calcium and cadherin transgene
What is EMT
epithelial-to-mesenchymal transition, nonmotile epithelial cells to motile cells
How is E-cadherin activity affected by EMT and cancer progression
Adhesion is lost, activity decreases
What are the main differences between classical and desmosomal cadherin?
Classical: two specialized cadherins: desmoglein and desmocolin
Desmosomal: interact with adaptor proteins such as plakoglobin
What are hemidesmosomes?
Specialized cell-matrix adhesion structures that are associated with the keratin cytoskeleton
What are tight junctions (kissing points)
Permeability barriers
prevent free exchange of solutes
Maintain polarity by separating the apical and basolateral ends
Made up of plasma membrane proteins
What are the main integral membrane proteins in tight junctions
Occludin: dispensable
Claudins: indispensable
What are claudins
Code 20-27 kda protiens wiht four transmemebrane proteins
Involved in Signaling pathways by C-terminal interaction
Structure and function of gap junctions
Cylinders of six dumbbell-shaped connexin molecules
Allow passage of ions and molecules smaller than 1200 Da
transmission in heart for muscle contraction
