17C Assignment

Question 1

Which of these statements about APC is false?

APC is a protease and promotes anaphase by degradation of securin, the protein that holds sister chromatids together.

APC is phosphorylated by the (mitotic) Cdk1-cyclinB and binds its activator Cdc20 to become active in metaphase.

APC is also active in ensuring exit from mitosis.

APC is an ubiquitin ligase and promotes anaphase by ubiquitin mediated degradation of securin.

Answer 1

APC is a protease and promotes anaphase by degradation of securin, the protein that holds sister chromatids together.

Question 2

Which of these proteins play a direct role in anaphase B?

Kinesin-5 on interpolar microtubules and dynein on kinetochore microtubules

Kinesin-13 on kinetochore microtubules and dynein on astral microtubules

Kinesin-5 on interpolar microtubules and kinesins 4 on interpolar and astral microtubules

Kinesin-5 on interpolar microtubules and dynein on astral microtubules

Answer 2

Kinesin-5 on interpolar microtubules and dynein on astral microtubules

Question 3

Which of these motor proteins are minus-end directed motors that cross link interpolar microtubules and pull the poles together?

Kinesin-5
Kinesin-14
Kinesin-4
Kinesin-10

Answer 3

Kinesin-14

Question 4

Duplication of centrosomes occurs in ________.

M phase
G1 phase
G2 phase
S phase

Answer 4

S phase

Question 5

Polar ejection force that pulls chromosomes to the spindle equator is mediated by ______.

Kinesin-5
Kinesin-4
Kinesin-14
Dynein

Answer 5

Kinesin-4

Question 6

The polar ejection force does which of the following?

Pulls the microtubules towards the spindle poles by microtubule flux

Pulls the kinetochore towards the poles by plus-end depolymerization

Pushes the chromosome arms away from the spindle poles with the help of kinesin-4 and 10

Pushes the chromosome arms towards the poles with the help of kinesin-5

Answer 6

Pushes the chromosome arms away from the spindle poles with the help of kinesin-4 and 10

Question 7

Which of the following statements is TRUE?

The contractile ring formation is inhibited by RhoA signaling.

The mitotic spindle helps segregate the chromosomes to the two daughter cells.

The mitotic spindle is largely made of intermediate filaments.

The contractile ring is made largely of actin filaments.

Answer 7

The mitotic spindle helps segregate the chromosomes to the two daughter cells.

Question 8

Some cell types in animals do not have centrosomes and therefore they do not have….

Chromatids
Kinetochore microtubules
Astral microtubules
Interpolar microtubules

Answer 8

Astral microtubules

Question 9

The plus ends of these microtubules are attached to large protein structures at the centromeres and they are called…………..

Kinetochore microtubules
Interpolar microtubules
Astral microtubules

Answer 9

Kinetochore microtubules

Question 10

Proper bi-orientation of the sister-chromatid pair on the spindle generates a tension that is sensed by_____.

Kinesin-5
Aurora-B kinase
Centrioles
Cohesins

Answer 10

Aurora-B kinase

Question 11

Degradation of securin is important for ________.

activation of Cdc20-APC/C complex
separation of sister chromatids
formation of spindle
inactivation of separase

Answer 11

separation of sister chromatids