Cytoskeleton Regulation Flashcards
MTs nucleate at the
Microtubule-organizing centre (MTOC)
Microtubules are nucleated from their _________ ends with the ______ end growing outward from the MTOC
minus, plus
_______ makes up the first part of the 13 part ring structure
MTOC
True of false: MTOC allows for skipping of the lag step
True (allows for first tubulin dimers to be added)
What happens if we mutate or remove the gamma tubulin from a cell
MTOC formation is extremely slow and less organized
What direction does MT grow in
in most cases, minus end is stabilized and plus end is growing or shrinking, UNLESS minus end is not bound by MTOC
Alpha is always toward the _____ _____ and beta toward the _______/_______ end
gamma tubulin, plus/growing end
Most animal cells have a single well-defined MTOC called the _________ located near the _______
centrosome, nucleus
_________ emanate from the centrosome in animal cells
microtubules
The cytoplasmic microtubules emanate in what kind of formation
Star-like
A centrosome is composed of a fibrous matrix that contains _____copies of γ-tubulin.
50
What end is anchored and stabilized at the MTOC
minus end
What cells and MTs do not always need to start at an MTOC
highly polarized cells, more stable MT’s
Embedded in the centrosome is a pair of structures called ________ arranged at right angles to each other.
centrioles
When do centrioles duplicate and when do they move to opposite poles of nucleus
Duplicate during cell division, move to opposite poles when mitosis begins
“Highway of the cell”
Microtubules
Nucleating sites
gamma-tubulin ring complexes
Centrioles are surrounded by a
centrosome matrix
Tubulin rings are capable of
polymerizing MTs
MT aster
MTOC with plus end growing outwards from centrosome and minus end anchored and stabalized
In animal cells, the astral configuration, with plus ends pointing out, acts as a device to
survey the outlying regions of the cell to position the centrosome at its center
Where is the cis-golgi network found
right near nucleus
Are MTOC found in differentiated cells (ex. epithelial cells that from cell-cell junctions, become highly polarized)
no
Actin filaments are often nucleated at the
plasma membrane
In contrast to microtubule nucleation, actin nucleation occurs most frequently at or near the _______ _______
plasma membrane
Actin nucleation can be catalyzed by 2 different regulated factors
-ARP complex
-Formins
What gives proper shape to nucleate actin monomers (branched)
Orientation of ARP2 and 3 proteins, (fit into ARP complex and starts to grow)
Filament nucleation by ARP occurs at __________ angles
70 degree angles
Where does ARP complex bind on polymer of straight actin
Middle
What type of actin is present at the growing tip of actin polymer
ATP