Microtubules

Question 1

unstable microtubule structure

Answer 1

singlet made of 13 protofilaments arranged in a cylinder

Question 2

examples of unstable/dynamic MT

Answer 2

spindle or centrosome

Question 3

exception to unstable singlet

Answer 3

axon MTs are stabilized by acetylation

Question 4

stable microtubules

Answer 4

doublets (13+10) and triplets (13+10+10)

Question 5

examples of MT doublets

Answer 5

cilia and flagella

Question 6

examples of MT triplets

Answer 6

centrioles and basal bodies

Question 7

gamma-tubulin ring complex

Answer 7

facilitates rapid nucleation of MTs; on plus end

Question 8

MTOC

Answer 8

microtubule organizing center on minus ends of microtubules

Question 9

interphase cell MTOC

Answer 9

centrosome

Question 10

dividing cell MTOC

Answer 10

spindle pole

Question 11

MTOC for ciliated cell

Answer 11

basal body

Question 12

MTOC’s provide _

Answer 12

directionality for movement

Question 13

GTP cap

Answer 13

provides stabilization at end of MTs

Question 14

GDP on microtubules

Answer 14

causes rapid disassembly and shrinkage

Question 15

acetylation

Answer 15

stabilizes microtubules

Question 16

drugs that destabilize MTs

Answer 16

colchicine, vinblastine, nocodozole

Question 17

drugs that stabilize MTs

Answer 17

taxol

Question 18

treadmilling

Answer 18

GTP adds to one end while GDP breaks off at another end –> results in what looks like forward motion of same sized strand

Question 19

example of MT treadmilling

Answer 19

when chromosomes move from metaphase plate towards spindle poles

Question 20

example of treadmilling in actin filaments

Answer 20

cilia in ears carrying sensations in

Question 21

basal body

Answer 21

9 triplet MTs

Question 22

primary cilia

Answer 22

sensory role in almost all non-dividing cells; intraflagellar transport

Question 23

primary cilia structure

Answer 23

axoneme (9 doublet MT) + 1 basal body

Question 24

motile cilia structure

Answer 24

axoneme (9+2 doublet MTs) and no basal body

Question 25

motile cilia

Answer 25

found on multi-ciliated epithelial cells in respiratory and reproductive tracts and brain

Question 26

motile cilia are required for _

Answer 26

EC fluid flow

Question 27

examples of ciliopathies

Answer 27

Bardet-Biedl Syndrome and polycystic kidney disease

Question 28

Bardet-Biedl Syndrome

Answer 28

mutation in genes encoding cilia intraflagellar transport

Question 29

symptoms of Bardet-Biedl Syndrome

Answer 29

retinal degeneration, loss of smell, kidney dysfunction, polydactyly, obesity, diabetes

Question 30

polycystic kidney disease

Answer 30

mutation in PKD1 and PKD2 that are found in primary cilia of kidneys

Question 31

polycystic kidney disease symptoms

Answer 31

renal cysts, hypertension, pain, and/or UTIs

Question 32

PKD hypothesis

Answer 32

primary cilia monitor fluid flow and regulate cell proliferation through calcium signaling through renal tubules --> loss of function blocks signaling pathway which leads to cell proliferation and cyst formation

Question 33

dynein

Answer 33

inner and outer arm on motile cilia to facilitate movement

Question 34

respiratory problems

Answer 34

immotile respiratory cilia

Question 35

sterility

Answer 35

immotile flagella in sperm and cilia in oviduct

Question 36

dynein provides _

Answer 36

retrograde movement (back to cell body); minus end motors

Question 37

cause of sinus inversus

Answer 37

bilateral symmetry is broken by fluid flow across nodal cells in base of embryo (because of dynein mess up

Question 38

kinesins

Answer 38

anterograde movement, plus end motors

Question 39

kinesins play a role in

Answer 39

spindle assembly, chromosome segregation, vesicle and organelle transport

Question 40

dyneins play a role in

Answer 40

cilia movement, vesicle transport

Question 41

myosin and kinesin _

Answer 41

evolved from same protein

Question 42

dynein evolved from _

Answer 42

AAA ATPase

Question 43

mechanochemical cycle of kinesin

Answer 43

ADP/ATP exchange in leading head causes lagging head to swivel forward; highly processive

Question 44

dynein microtubule motor

Answer 44

tail bound to cargo or MT --> goes to first ATP domain --> goes through domains 1-4 --> at stalk, goes up to bind MT --> then goes through 5 and 6 domain

Question 45

axonemical/ciliary dynein

Answer 45

dimer or trimer, defective genes in kartagener syndrome

Question 46

cytoplasmic dynein

Answer 46

dimer; vesicle movement, spindle and chromosome segregation

Question 47

communication between actin and microtubules

Answer 47

cell migration, spindle orientation, vesicle trafficking, immunological synapse