Question : 11) What would be the consequence of inactivation of the : 2134337

11) What would be the consequence of inactivation of the E2F complex?

A. Cells would be unable to enter the S phase of the cell cycle.

B. Cells would immediately enter the S phase of the cell cycle.

C. Cells would rapidly proliferate and form a tumor.

D. The retinoblastoma protein (pRB) would become activated.

12) Regulatory proteins that serve to prevent a cell from entering the S phase of the cell cycle under conditions of DNA damage are also known as:

A. cyclins

B. cyclin-dependent kinases

C. oncoproteins

D. tumor suppressors

13) Progression through the cell cycle is regulated by oscillations in the concentration of which factor?

A. cyclin-dependent kinases

B. cyclins

C. actin

D. tubulin

14) If DNA damage occurs early in G1 of the cell cycle, the tumor suppressor protein p53

A. activates the p21 gene which encodes a CDK inhibitor, thereby causing G1 arrest.

B. promotes apoptosis.

C. phosphorylates the retinoblastoma protein (pRB), thereby blocking the cell cycle.

D. is targeted for degradation by the proteasome.

15) In addition to promoting cell cycle arrest via cyclin/Cdk complexes in response to cytotoxic conditions such as DNA damage, the tumor suppressor p53 may

A. initiate programmed cell death.

B. induce the degradation of oncoproteins

C. stimulate translational arrest by phosphorylated eIF2a.

D. cause cells to stop growing by limiting glycolysis.