Which of the following does not occur during M phase in animal cells?

Which of the following does not occur during M phase in animal cells?

(a) growth of the cell
(b) condensation of chromosomes
(c) breakdown of nuclear envelope
(d) attachment of chromosomes to microtubules

Answer: 

You create cells with a version of Cdc6 that cannot be phosphorylated and thus cannot be degraded. Which of the following statements describes the likely consequence of this change in Cdc6?

You create cells with a version of Cdc6 that cannot be phosphorylated and thus cannot be degraded. Which of the following statements describes the likely consequence of this change in Cdc6?

(a) Cells will enter S phase prematurely.
(b) Cells will be unable to complete DNA synthesis.
(c) The origin recognition complex (ORC) will be unable to bind to DNA.
(d) Cdc6 will be produced inappropriately during M phase.

Answer: 

How does S-Cdk help guarantee that replication occurs only once during each cell cycle?

How does S-Cdk help guarantee that replication occurs only once during each cell cycle?

(a) It blocks the rise of Cdc6 concentrations early in G1.
(b) It phosphorylates and inactivates DNA helicase.
(c) It phosphorylates the Cdc6 protein, marking it for destruction.
(d) It promotes the assembly of a prereplicative complex.

Answer: 

Which of the following statements is false?

Which of the following statements is false?

(a) DNA synthesis begins at origins of replication.
(b) The loading of the origin recognition complexes (ORCs) is triggered by S-Cdk.
(c) The phosphorylation and degradation of Cdc6 help to ensure that DNA is replicated only once in each cell cycle.
(d) DNA synthesis can only begin after prereplicative complexes assemble on the ORCs.

Answer: 

Cells in the G0 state ________________.

Cells in the G0 state ________________.

(a) do not divide.
(b) cannot re-enter the cell cycle.
(c) have entered this arrest state from either G1 or G2.
(d) have duplicated their DNA.

Answer: 

The G1 DNA damage checkpoint ________________.

The G1 DNA damage checkpoint ________________.

(a) causes cells to proceed through S phase more quickly.
(b) involves the degradation of p53.
(c) is activated by errors caused during DNA replication.
(d) involves the inhibition of cyclin-Cdk complexes by p21.

Answer: 

The Retinoblastoma (Rb) protein blocks cells from entering the cell cycle by ______.

The Retinoblastoma (Rb) protein blocks cells from entering the cell cycle by ______.

(a) phosphorylating Cdk.
(b) marking cyclins for destruction by proteolysis.
(c) inhibiting cyclin transcription.
(d) activating apoptosis.

Answer: