Test 2 Cytoskeleton Flashcards
T/F: A cell can change its shape using its cytoskeleton.
True
Where is actin found?
Toward the periphery of the cell.
What are the intermediate filaments of the cell?
Actin and tubulin. They build a network within the cell.
T/F: The cytoskeleton determines cellular organization and polarity.
True
What are the 3 different filaments that compose the cytoskeleton?
Actin filaments, intermediate filaments and microtubules.
What is the structure of microtubules?
Hollow cylindrical structures built from protofilaments composed of alpha-tubulin heterodimers stacked head to tail and folded into a tube.
What is protofilaments?
Tubulin subunits composed of alternating alpha-tubulin and beta-tubulin.
What happens to GTP at the GTP binding site of alpha-tubulin?
GTP is trapped, it is never hydrolyzed nor exchanged.
What happens to GTP at the GTP binding site of beta-tubulin?
GTP is hydrolyzed.
What is dynamic instability?
Influences by the binding and hydrolysis of GTP on the beta-subunit of the tubulin dimer. Addition of GTP allows the protofilament/microtubule to grow, while GTP hydrolysis creates the protofilament/microtubule to shrink.
What is the MTOC?
Microtubule organizing center: where microtubules originate.
What are the (2) motor-proteins associated with microtubules?
Kinesin and dynein.
Toward which end does kinesin travel on the microtubule?
Toward the plus end.
Toward which end does dynein travel on the microtubule?
Toward the minus end.
What is the purpose of MAPs?
Moving organelles and vesicles in the cell.
What are flagella used for?
Movement of cells in a liquid environment.
T/F: Cilia can move fluid above a cell.
True
What is the structure of an actin filament?
Consists of (2) parallel protofilaments, which is a flexible helical structure. Has a plus and minus end.
What is the function of intermediate filaments?
Maintenance of cell shape, organelle attachment, and formation of the nuclear lamina. Example: Keratin
What is the function of actin microfilaments?
Maintenance of cell shape, changes of the cell shape, muscle contraction, and cell movement.
What is the function of tubulin microtubules?
Maintenance of cell shape, cell movement, chromosome movement during cell division, and movement of organelles.
Where are actin microfilaments found within the cell?
In the periphery of the cell, sometime running parallel.
Where are tubulin microtubules found within the cell?
Coming from an organizing center and spreading towards the cell periphery. Example: centrosomes.
Where are intermediary filaments found within the cell?
Distributed along the whole cytoplasm of the cell, building a network of filaments in the cytosol.
What is the subunit for microfilaments?
Actin.
What is the subunit for microtubules?
Tubulin (alpha and beta).
What is the subunit for intermediary filaments?
Keratin, Lamin, and Vimentin.
What is the structure of microfilaments?
Two helical crossed actin strands.
What is the structure of microtubules?
Tubes of 11-18 strands per microtubule.
