Cytoskeleton: Microtubules: Cilia & Flagella

Question 1

What is the MTOC of an axoneme?

Answer 1

basal body

Question 2

Describe the cytoskeletal structure in cilia & flagella

Answer 2

9 microtubule doublets surrounding 2 microtubule singlets

Question 3

The microtubules in flagella and cilia are continuous with ____ _____

Answer 3

basal body

Question 4

What is attached to every doublet microtubule in cilia/flagella?

Answer 4

dynein motor protein - there is inner and outer dynein arms associated with each outer microtubule doublet

Question 5

What makes the movement/bending of cilia and flagella?

Answer 5

dynein arms slide one part of dublet, so the doublets are sliding relative to each other.

Question 6

The motor proteins don’t actually slide, they bend - why?

Answer 6

There are linking proteins that prevent sliding, so when motor proteins walk , the microtubules bend

Question 7

Key words: dynein, recurrent infections, situs inversus, sinusitis, infertility are what disease?

Answer 7

Primary Ciliary Dyskinesia (PCD) – Kartagener Syndrome

Question 8

Characteristics: Kartagener syndrome: bronchiectasis, situs inversus, chronic paranasal sinusitis, infertility are what disease?

Answer 8

PCD

Question 9

What is the mode of inheritance for PCD?

Answer 9

AR

Question 10

What is missing with PCD?

Answer 10

Lack of dynein arms or defect of inner dynein arms

Question 11

What is the mechanism for PCD?

Answer 11

Total lack of dynein arms or defect of inner dynein arms →immotility of cilia & sperm → retention of secretions & recurrent infections (bronchitis, otitis media, & sinusitis); decreased ciliary activity affects cell motility during embryogenesis → situs inversus

Question 12

50% of people with PCD will develop what?

Answer 12

Kartagener syndrome

Question 13

What are symptoms of kartagener syndrome? Why are they symptoms?

Answer 13

Bronchiectasis
Situs inversus
Chronic paranasal sinusitis
Infertility

Lungs, sinus, etc are all places where cilia are really important for function. If you don’t have cilia to move crap out of your lungs you will get infections

Question 14

What is situs inversus?

Answer 14

Condition where majority of organs are reversed or mirrored from normal positions

Question 15

Why does situs inversus occur with PCD?

Answer 15

cilia are important during embryogenesis for moving organs to correct position

Question 16

Colchine, Vincristine & Vinblastine are drugs that bind what?

Answer 16

tubulin subunits & prevent polymerisation

Question 17

What is colchine used to treat?

Answer 17

gout

Question 18

What is vincristine used to treat?

Answer 18

cancer

Question 19

What is vinblastine used to treat?

Answer 19

cancer

Question 20

How do drugs that bind tubulin block mitosis?

Answer 20

If you can’t form spindle you can’t go through mitosis

Question 21

Name a drug that inhibits depolymerisation by binding and stabilizing microtubules

Answer 21

Paclitaxel (Taxol)

Question 22

What is Palcitaxel used to treat?

Answer 22

cancer

Question 23

What is another name for palcitaxel?

Answer 23

taxol

Question 24

How does palcitaxel stop mitosis?

Answer 24

The spindle can form, but microtubules need to be broken down in order to pull chromatids apart and become two cells. When they can’t break apart, mitosis can’t complete