L26-Cytoskeletal microtubules, microfilaments and motility. Flashcards

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1
Q

what is the cytoskeleton?

A

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

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2
Q

name the 3 types of cytoskeleton

A

1) microtubules
2) microfilaments
3) intermediate filaments

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3
Q

describe the structure of the microtubules

A

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.

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4
Q

what does it mean that the microtubules are dynamic structures?

A

it means that they can change in length according to the cells requirement.

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5
Q

what is a protofilament?

A

they are longitudinal arrangements of the dimers forming a long chain.

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6
Q

state the number of protofilaments in every microtubules.

A

13 protofilaments

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7
Q

what are the centrosomes?

A

microtubule organizing center, it’s a region close to the nucleus. it houses the centrioles and several hundred of the gamma tubular rings.

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8
Q

what are the functions of the microtubules?

A

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.

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9
Q

what is colchicine and describe its action.

A

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

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10
Q

what are microtubules associated proteins?

A

they are protein that help transport vesicle and organelles inside the cell and prevent the depolymerization of the microtubules.

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11
Q

name the 2 types of microtubules associated proteins.

A

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.

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12
Q

what are centrioles?

A

they ae small cylindrical structure composed of 27 microtubules arranged in triplets. they are a paired structure perpendicular to each other.

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13
Q

what is the function of the centrioles?

A

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)

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14
Q

Describe the structure of actin filament

A

its made up of 2 chains of actin globular proteins coiled around each other

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15
Q

what are the functional forms of actin filament?

A

1 contractile bundels
2 gel like networks
3 bundles
4 focal points

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16
Q

describe the function of contractile bundles?

A

the actin filaments here are arranged loosely and anti parallel to each other
1 they form cleavage furrow (contractile ring) during mitosis
2 movement of organelles and vesicles inside the cell
3 cellular activities such as exocytosis endocytosis and cellular extensions

17
Q

describe the function fo the gel like networks.

A

provide the structural foundation of the cell cortex

18
Q

describe the function of bundles of actin filament

A

its forms the core of microvilli (cell projections)

19
Q

describe the function of focal points

A

they are points of contact between the cell and extracellular matrix