Rea Final Practice

Agents that interfere with the dynamic instability of moelcules, including taxol, colchicine, and cincristine, are effective anti-cancer chemotherapeutics. Why is taxol less toxic to normal cell?

Taxol stabilizes MTs

MPF refers to the substance present in the cytosol of Xenopus Ooxytes that is capable of driving multiple cycles of M phase and S phase in virtro. What is MPF

Maturation promoting factor

As the metaphase-anaphase checkpoint, anaphase promoting complex (APC) ubiquinates which of the following proteins to release separase from inhibition?

Securin

Where in the motile cell would you expect to find most ARP complex?

In the lamellipodium - leading edge

During the movement of kinesin dimer along a MT, which of the following events is responsible for the "power stroke"?

ATP exchange for bound ADP on the leading head.

Which of the following proteins promotes the depolymerization of actin filaments near the lamellipodium of a motile cell?

Cofilin

How does cytochome C promote apoptosis via the intrinsic pathway?

By promoting the aggregation of initiator procaspases.

Which of the following intermediate filament proteins that are exclusively expressed in epithelial cells?

Keratin

Which of the following statements is true regarding most kinesin motor proteins?

They hydrolyze ATP and move towards the + end of the MTs

What is the source of the calcium that permits contraction of skeletal muscle?

Sarcoplasmic reticulum

What provides the force that drives chromosomal segregation during Anaphase A?

Catastrophic fraying of kinetochore MTs

In addition to the activation of Cyclin-dependent protein kinases, what is the role of the cyclin subunit?

Determines the substrate specificity of the kinase

Which of the following proteins replaces cdc20 to maintain anaphase promoting complex (APC) activity during G1 phase?

Cdh1

How does the Akt kinase inhibit apoptosis?

By phosphorylating the BAD protein and releasing the anti-apoptotic protein, Blc2

During movement of myosin motor proteins long actin filaments, which of the following results in release of the motor head from the actin filament?

ATP binding

Growth factor signal through the AKT kinase, resulting in the phosphorylation and activation of which of the following?

TOR

Which of the following statements regarding cytoplasmic dyneins is true?

They hydrolyze ATP and move towards the minus end of MTs

Which of the following kinesins promotes catastrophic depolymerization of MTs?

Kinesin 13

Which of the following are intermediate filament proteins that are expressed in eukaryotic cells?

Nuclear Lamins

Which of the following proteins serve as the plus end capping protein of actin filaments in the sarcomere?

Cap Z

Which of the following kinases is responsible for preventing assembly of Ndc80 complexes on kinetochore MTs?

Aurora-B-Kinase

What are caspases?

Proteases that cleave substrates at specific aspartate residue

How do activated T-cells initiate apoptosis via extrinsic pathway?

By activating the Fas death receptor on the target cell.

How does the cytochome C escape mitochondria to promote apoptosis?

By leaving through channels in the outer membrane made by BH123 proteins.

When significant DNA damage is detected during G1 phase, P53 is release from inhibition and arrests cell cycle at the start checkpoint to prevent replication of damaged DNA. How does P53 prevent entry into S phase?

By promoting the transcription of Cdk inhibitors.

Which of the following substrates is phosphorylated by the PI3 kinase?

Phosphatidylinositol 4,5-biphosphate

Which of the following is NOT a MT organizing center?

Centriole

At the M-phase checkpoint, which of the following proteins is the phosphatase that removes inhibitory phosphate group from M-Cdk complex?

Cdc25

During movement of myosin motor proteins along actin filaments, which of the following events results in "power stroke"

Dissociation of Pi

Which of the following is NOT a substrate of the M-Cdk complex?

Cohesion

Which of the following is NOT an actin-rich structure?

Vertebrate cilia

Which of the following protein determines the packing density of MTs in axons?

Tau

At the leading edge of a motile cell, which of the follwoing events provides the force that drives the lamellipodium forward?

Actin Polymerization

You have isolated a temperature sensitive yeast mutant. When maintained at the restrictive temperature, all of the yeast cells are arrested at the Metaphase-Anaphase Checkpoint due to loss of function mutation of a single cell. Which of the following protein complexes is most likely to be responsible for this?

APC/C

During S-phase which of the following is phosphorylated by S-Cdk complex to prevent a second round of DNA synthesis?

ORC

Which of the following protein complexes can nucleate actin polymerization in the absence of existing actin filament?

Formin dimers

Failure of anaphase promoting complex (APC) to ubiquinate this protein would result in arrest of cell cycle at anaphase. Which of the following is this protein?

Cyclin B

Un-capped actin filaments "grow" - polymerize at the plus end. What happens at the minus-end?

Depolymerization

The AKT kinase is recruited to the plasma membrane by which of the following membrane associated molecules?

Phosphatidyl inositol 3,4,5-triphosphate

What is the term for the SMC protein complexes that gather and pack newly replicated DNA into chromosomes?

Condensins

Prolactin and some cytokines alter gene expression through which of the following transduction pathways?

JAK-STAT pathway

Disintegration of the nuclear lamina and the nuclear envelope occurs during which phase of mitosis?

Prometaphase

Which of the following kinesin motor proteins binds directly to chromatin?

Kinesin 4,10

How does the anti-apoptotic protein, Bcl2, prevent apoptosis?

By preventing the aggregation of BH123 proteins.

Which of the following statements about MTs is false?

They are found only in soft bodied organisms.

What is the term for the smallest contractile unit of skeletal muscle?

Sarcomere

At which phase of the cell cycle of the SMC protein complexes that prevent premature separation of sister chromatids first assemble around DNA?

G1 phase

Which of the following proteins is responsible for phosphorylation and activation of M-CDK?

Wee1

Which of the following is the inhibitory binding partner for transcription factor E2F

Rb protein

Which of the following Cdk complex / cyclin mates is incorrect?

G1-CDK and Cyclin C