Exam 4

Question 1

Which type of microtubule-kinetochore attachment describes the condition in which both sister chromatids are captured by microtubules from the same spindle pole/centrosome?

Answer 1

Amphitelic

Question 2

Active Cdk4/6 complexed with cyclinD is indicative of which cell cycle transition?

Answer 2

G1 to S

Question 3

Phosphorylation of GM130 during prophase leads to which event?

Answer 3

Fragmentation of the Golgi

Question 4

Which of the following accurately describes the events associated with Anaphase A and B?

Answer 4

Anaphase A is when the chromosomes travel toward the poles; Anaphase B is when the poles move apart

Question 5

Rigor mortis in a corpse is due to the muscle rigidity that occurs when myosin in skeletal muscle stays tightly bound to actin filaments and is unable to release. This is because myosin can not enter the low affinity state with actin, which is the ____

Answer 5

ATP-bound state

Question 6

Microvilli contain crosslinked
__ and flagella contain crosslinked __

Answer 6

Actin filaments; microtubules

Question 7

Intermediate filaments are anchored to intercellular junctions known as ____ and to protein networks that anchor cells to the extracellular matrix known as ___

Answer 7

Desomosomes; hemidesmosomes

Question 8

Light chains serve as cargo adaptors for which of the motors?
1. Myosin
2. Kinesin
3. Dynein

Answer 8

2 and 3 only

Question 9

If an acidic keratin (i.e. Class I keratin) is expressed in a cell, which other intermediate filament protein will be expressed?

Answer 9

basic keratin

Question 10

In regards to the biochemical control of the cell cycle, ____ tends to activate forward progress of the cell cycle, while ____ prevents regression to a previous stage of the cycle

Answer 10

phosphorylation; ubiquitylation

Question 11

Which of the following is a characteristic of intermediate filaments that distinguishes them from both actin and microtubules?

-Intermediate filaments do not bind nucleotide
-Intermediate filaments do not have distinct polarity
-Intermediate filaments do not have any motor proteins that associate with them
-Two of the above
-All of the above

Answer 11

All of the above

Question 12

____ causes the nuclear lamina to disassemble in ____

Answer 12

Phosphorylation of lamins by Cdk; prometaphase

Question 13

In the DNA Damage Checkpoint pathway, which of the following is a transcription factor that induces the expression of a cohort of genes that halt cell cycle progression?

Answer 13

P53

Question 14

Which of the following is true regarding tumor suppressors?
-They normally block cell cycle progression
-Individuals with mutations that block tumor suppressor function are at higher risk for cancer
-Rb and p16 |kna are examples
-Two of the above
-All of the above

Answer 14

All of the above

Question 15

When retinoblastoma (R) is phosphorylated, E2F/DP1 acts as a transcriptional _____ and the cell ____ the restriction point

Answer 15

Activator; surpasses

Question 16

Myosin and dynein share the same force-generating steps in their ATPase cycles. What is it?

Answer 16

Release of hydrolyzed phosphate

Question 17

Many hair products that straighten or curl hair alter the disulfide and amide bonds of which intermediate filament protein?

Answer 17

Keratin

Question 18

What would you expect to happen in a cell that has no Cdc25 activity?

Answer 18

The cell would be unable to enter M phase from G2

Question 19

Dynein moves toward the ___ end of a microtubule, while myosin moves toward the ___ end of an actin filament

Answer 19

Minus; barbed

Question 20

During interphase, the rate of microtubule catastrophe is about one per minute. But microtubules in the cell have a half life of about 10 minutes. What accounts for this?
-Microtubules depolymerize very slowly
-Microtubules continue to grow after catastrophe
-The rate of rescue is relatively high
-Two of the above
-All of the above

Answer 20

The rate of rescue is very high

Question 21

APC/CCdh1 is a(n) ____ that is most active during the ___ phase of the cell cycle.

Answer 21

E3 ubiquitin ligase; G1

Question 22

Which of the following is NOT involved in the positioning and assembly of the mitotic spindle?

Answer 22

Emi1

Question 23

Which of the following is the largest of the cytoskeletal motors?

Answer 23

Dyneins

Question 24

Why does Cyclin B accumulate in the nucleus in Prophase?

Answer 24

Its nuclear export signal gets phosphorylated

Question 25

Which of the following contributes to the activation of Cdk1-cyclinB at the G2/M transition?
-Phosphorylation of cyclin B by Polo kinase
-Phosphorylation of Cdc25 by Polo kinase
-Phosphorylation of Polo kinase by Cdk1-cyclinB
-Two of the above
-All of the above

Answer 25

All of the above

Question 26

Separase is a(n) ____ that when active leads to the degradation of ___

Answer 26

Protease; cohesin

Question 27

What is found at high concentration in centromeres and facilitates the nucleation of microtubules?

Answer 27

Gamma-tubulin ring complex

Question 28

The MRN complex is recruited to sites of ______ and helps to recruit ____

Answer 28

Double strand breaks; ATM

Question 29

Breakdown of the nuclear envelope is a key component of ____ and is caused by ____ activity

Answer 29

Prometaphase; kinase