L26-Cytoskeletal microtubules, microfilaments and motility. Flashcards
what is the cytoskeleton?
they are structural proteins found in the cytoplasm used to maintain the cell shape and regulate intracellular movement whether of an organelle or a vesicle
name the 3 types of cytoskeleton
1) microtubules
2) microfilaments
3) intermediate filaments
describe the structure of the microtubules
they are long hollow and non branching tubes made form small subunits called tubulins they can be alpha or beta. they unite together to form a dimer.
what does it mean that the microtubules are dynamic structures?
it means that they can change in length according to the cells requirement.
what is a protofilament?
they are longitudinal arrangements of the dimers forming a long chain.
state the number of protofilaments in every microtubules.
13 protofilaments
what are the centrosomes?
microtubule organizing center, it’s a region close to the nucleus. it houses the centrioles and several hundred of the gamma tubular rings.
what are the functions of the microtubules?
1- provide rigidity for the cell
2- regulate intracellular movement
3- establish intracellular compartments
4-during cell division microtubules are responsible for the formation of the mitotic spindle.
what is colchicine and describe its action.
colchicine is a drug that bind with the tubulins of the leukocyte preventing the polymerization of microtubules. Therefore, interferes with the leukocytes movement and phagocytosis and further release of inflammatory substance
what are microtubules associated proteins?
they are protein that help transport vesicle and organelles inside the cell and prevent the depolymerization of the microtubules.
name the 2 types of microtubules associated proteins.
dynein and kinesine
dynein moves toward the negative end of the microtubule while kinesis moves towards the positive end.
this process is active and requires ATP.
what are centrioles?
they ae small cylindrical structure composed of 27 microtubules arranged in triplets. they are a paired structure perpendicular to each other.
what is the function of the centrioles?
1- they assist in the formation and organization of the microtubules.
2- formation of the spindle apparatus
3- they are basal bodies that guide the formation fo Celia and flagella (cell motility)
Describe the structure of actin filament
its made up of 2 chains of actin globular proteins coiled around each other
what are the functional forms of actin filament?
1 contractile bundels
2 gel like networks
3 bundles
4 focal points