Lesson 9 Cytoskeleton

Front 1

Microtubules

Back 1

hollow cylindrical cytoskeleton filaments formed from tubulin

Front 2

polarized cells

Back 2

cells displaying unever distributions of cellular components and fxns

Front 3

protofilament

Back 3

linear arrays of cytoskeletal subunits joined end to end

Front 4

nucleation

Back 4

the initial and rate limiting step of cytoskeleton filament formation it is the formation of aggregate subunits stablized by numerous subunit to subunits interactions

Front 5

critical concentration

Back 5

conc of free cytoskeletal subunits at which the rate of subunit addition equals the rate of subunit loss and filament elongation stops

Front 6

Dynamic Instability

Back 6

term refering to the rapid conversion between growth and shrinkage of microtubuls and actin filaments

Front 7

GTP cap

Back 7

The presence of a GTP-tubulin subunit at the plus end of microtubules; stabilizes the plus end and favors filament elongation

Front 8

Castrophe

Back 8

the rapid shrinkage of a microtubule

Front 9

Rescue

Back 9

The switch between shrinkage and elongation of microtubules

Front 10

Treadmilling

Back 10

the rate of subunit addition to the plus end is equal to the rate of subunit loss from the minus end making it appear as if the filament was moving

Front 11

Microtubule organizing center MTOC

Back 11

site within cells where microtubule nucleation occurs

Front 12

?-tubulin ring complex (?-TuRC complex)

Back 12

ring structures which nucleate the formation of microtubules and remain attached to and stabilize their minus end

Front 13

Centrosome

Back 13

the primary site of microtubule nucleation, it contains multiple ?-TuRC and other proteins, many of which are uncategorized, surrounding a pair of centrioles

Front 14

Axoneme

Back 14

core structure and flagella consisting of nine doublet microtubules surrounding a central pair

Front 15

Centrioles

Back 15

pair of short, cylindrical structures oriented at right angles within centrosomes; organization the fibrous matrix and form the spindle poles during cell division

Front 16

Basal bodies

Back 16

structures located near the cell surface from which cillia and flagella arise; structure similar to centrioles with nine triplet microtubules arranged in a cartwheel formation

Front 17

Stathmin

Back 17

protein which binds microtubule subunits and inhibits their assembly onto a microtubule

Front 18

Katanin

Back 18

microtubule severing protein

Front 19

MAP
Microtubule associate protein

Back 19

any of a number of proteins which bind to and modify the properties of microtubules

Front 20

MAP2

Back 20

microtubule associated protein which mediates the formation of widely spaced microtubule arrays

Front 21

Tau

Back 21

microtubule associated protein which mediates the formation of closely spaced microtubule arrays; forms neurofibrary tangles associated with Alziehmers disease

Front 22

Catastrophe factors

Back 22

proteins which bind to plus ends and increase catastrophe rate of microtubules by prying apart photofilaments

Front 23

XMAP215

Back 23

protein which binds to and stabilizes the plus ends of microtubules

Front 24

kinesins

Back 24

family of plus end directed (one exception) motor proteins which use the energy of ATP hydrolysis to move along microtubules

Front 25

Dyneins

Back 25

Family of directed minus end motor proteins which use the energy of ATP hydrolysis to move along microtubules

Front 26

Anterograde movement

Back 26

Kinesin mediated movement of vesicles and organelles from nerve cell bodies to axon terminals

Front 27

retrograde movement

Back 27

Dynein mediated movement from axon terminals back towards nerve cell bodies

Front 28

Cilia

Back 28

hair like cellular projections containing axenomal cores and beating with a whip like motion resembling the breast stroke

Front 29

Flagella

Back 29

hair like cellular projections containing axenomal cores and beating with a wave like motion capable of propeling sperm through aqueous environments

Front 30

Nexin links

Back 30

protein structures linking adjacent doublet microtubles of axonemes

Front 31

primary cilia

Back 31

non-motile cilia lacking dynein arms and central pairs

Front 32

ciliopathies

Back 32

human disease linked to defects in cilia

Front 33

centripetal movement

Back 33

movement towards cell center

Front 34

centrifugal movement

Back 34

movement away from cell center towards cell periphery (this of a centrifuge!)

Front 35

TF
The minus ends of microtubules grow at a faster rate than the plus ends.

Back 35

False

Front 36

Motor proteins which walk towards the plus ends of microtubules.

Back 36

Kinesins

Front 37

TF
Profilin-bound tubulin subunits are prevented from adding onto the plus ends of microtubules

Back 37

false

Front 38

TF
Protofilaments are a structural component of all cytoskeletal filaments

Back 38

True

Front 39

TF
The dynamic instability of microtubules allows cells to be flexible and respond very quickly to internal or external signals

Back 39

true

Front 40

TF
Axonemal dyneins are only found in cilia and flagella.

Back 40

True

Front 41

TF
The core structures found in cilia and flagella are composed of nine triplet microtubules arranged in a cartwheel formation.

Back 41

False

Front 42

TF
ATP-caps stabilize the plus ends of microtubules.

Back 42

False