Mfm Test 1 - Cytoskeleton

Front 1

what are the functions of cytoskeleton?

Back 1

- gives the cell its shape
- holds organelles in place
- coordinates molecular traffic inside the cell
- allows for movement and changes in the shape of cell

Front 2

what are the 3 components of cytoskeleton ?

Back 2

- intermediate filaments
- microtubules
- actin filaments

Front 3

what is general shape of intermediate filaments?

Back 3

8 tetramers twisted into rope like filament

Front 4

which is the most durable of the cytoskeleton filaments?

Back 4

intermediate filaments

Front 5

what is primary role of itermediate
filaments?

Back 5

enables cell to withstand mechanical stresses

Front 6

what are 4 classes of intermediate filaments?

Back 6

1) keratins
2) vimentin and vimentin related
3) neurofilaments
4) nuclear laminin
first 3 are cytoplasmic and last is nuclear

Front 7

where can we find keratin filaments?

Back 7

in epithelia

Front 8

where can we find vimentin filaments?

Back 8

in connective tissue,
muscle cells,
glial cells

Front 9

where can we nuclear laminin ?

Back 9

in all animal cells

Front 10

what kind of cells need intermediate filaments?

Back 10

they are prominent in cells that need to withstand various mechanical stresses , like skin cells, long axons of nerve cells, and muscle cells

Front 11

in which type of cell junction can we find intermediate filaments?

Back 11

desomosomes and hemidesmososmes

Front 12

what is specific about nuclear lamina?

Back 12

intermediate filaments instead of forming ropeliek structure , make mesh structure

Front 13

what are lamins?

Back 13

intermediate filaments that make nuclear lamina

Front 14

which filaments are called "highway of the cell"?

Back 14

microtubules

Front 15

what is organization of microtubules?

Back 15

they are composed of arrays of alfa and beta tubulin dimers that form protofilaments organized around a hollow core

Front 16

describe polarity of microtubules

Back 16

plus end is beta tubulin end (peripheral)
minus and is alfa and ( close to nuceus)

Front 17

are microtubules static or dynamic?

Back 17

they are very dynamic , especially during metosis

Front 18

where are microtubules present?

Back 18

in all nucleated cells and in the platelets in the blood

Front 19

what is "dynamic instability?"

Back 19

it is characteristic of the microtubules - they rapidly grow and shrink, due to the GTP hydrolysis activity of the alfa and beta tubulin dimers.
GTP dimers pack tighlty and GDP dimers pack more more loosely, and later they tend to dissociate, resulting in microtubules shrinkage from the minus end

Front 20

are all microtubules dynamic?

Back 20

no, some are stabilized by various proteins and complexes ( capping proteins), this allows for specialized structures in some cells,

Front 21

give an example of micritubule stabilizing protein

Back 21

tau protein in neuronal axons

Front 22

what is the different name of centrosome ?

Back 22

MTOC - microtubule organizing center

Front 23

describe centrosome

Back 23

it is comprised of a pair of orthogonally postioned centrioles surrounded by pericentriolal material

Front 24

when is centrosome duplicated?

Back 24

in S phase

Front 25

what is the role of centrosome in mitosis?

Back 25

in mitosis the two centrosomes form the poles of the mitotic spindel

Front 26

what microscope do we need to observe centrioles in centrosome?

Back 26

we need electron microscope because the distance between the 2 is less than 200 nm

Front 27

name of the site that microtubules grow from

Back 27

gamma turk

Front 28

describe micortubule molecular motors

Back 28

- transport organelles and membrane-bound vesicles to their target locations within cell
- movement is unidirectional
- movement requires energy from ATP

Front 29

list two proteins associated with microtubule-associated molecular motors

Back 29

kinesin and dynein

Front 30

role of kinesin

Back 30

moves toward the plus end of microtubule

Front 31

role of dynein in the microtubule-associated molecular motor

Back 31

moves toward the minus end of microtubule

Front 32

describe roles of the particular parts of microtubula molecular motrs

Back 32

heads move , tails are associated whit the cargo

Front 33

describe vesicle transport along the axon

Back 33

kinesins transport material along the axon towards the axon terminal and dyneins move materials from the axon terminal to the cell body

Front 34

list the cellular appendages made by microtubules

Back 34

cilia and flagella

Front 35

what is different name for cellular appendages ?

Back 35

undulipodia

Front 36

describe celia

Back 36

hair- like structures covered by plasma membrane that extend from the cell surface, many cilia per cell,
9+2 ,

Front 37

describe flagella

Back 37

structurally similar to cilia but only one per cell, in humans only found on sperm cells

Front 38

describe the structure of cilia and flagella

Back 38

- both consist of axoneme,
- 9+2
- nexin
- ciliary dynein ( axonemal dynein)
- radial spoke

Front 39

describe the role of nexin in cilium

Back 39

a protein that connects adjacent microtubule doublets, but also keeps them separated

Front 40

what is ciliary dynein ?

Back 40

motor protein associated with axonemes

Front 41

where can u find cilia

Back 41

respiratory epithelium and fellopian tubes

Front 42

describe ciliary ( or flagellar) movement

Back 42

in axonemses , movement of ciliary dynein along adjacent microtubule doublets causes bending;
this bending is translated into movement of the entire axoneme

Front 43

in which cells can we find actin filaments?

Back 43

in all cells

Front 44

what is different name for actin filaments?

Back 44

thin filaments or f-actin

Front 45

what are actin subunits called?

Back 45

g-actin

Front 46

what is role of the actin filaments?

Back 46

- they play a role in cellular movement , associate with molecular motor myosin,
- form microvilli,
-form contractile bundles in hte cytoplasm,
- form sheet like and finger like protrusions on the leading edge of motile cells,
- form contractile ring during cell division

Front 47

describe actin filaments

Back 47

actin filaments consist of 2 stranded helix and similarly to microtubules , they also have polarity

Front 48

what are differences between cillia and microvilli

Back 48

- motile vs non-motile;
- different role in the cell,
- microtubules vs actin filaments,
- basal body vs base of microvilli maed from actin

Front 49

what is different about actin filamnets found in muscle cells?

Back 49

actin filaments are very dynamic but in muscle cells actin filaments are structurally stable

Front 50

describe actin filaments dynamics

Back 50

actin filaments can grow on one end ( plus end) while symultaneously disassemble form the opposite end ( minus end) which looks like a treadmilling and cause net movement along the polymer

Front 51

compare actin filaments dynamics with microtubule dynamics

Back 51

- both grow form one end ( plus end)
- in both, hydrolysis of a nucleotide triphosphate results in release of the monomer ( actin) or dimer ( tubulin),
- in microt. it is GTP
- in actin fil. it is ATP
- actin filaments shrink from the minus end while microtubules shrink from the plus end

Front 52

describe the actin molecular motors

Back 52

analogically to microtubules kinesin and dynein, in actin filaments we have myosin family of molecular motors,
they move toward the plus end of the actin filament

Front 53

describe the role of actin and myosin in muscle contraction

Back 53

in muscles , myosin 2 molecules can associate with one another to form thick filaments of myosin .
The myosin heads of these filaments walk along the actin filaments toward the plus end ( associated with the z disc)
this produces shortening of the sarcomere and muscle contraction