chapter 14

DNA synthesis occurs during which phase of the cell cycle?

S phase

Checkpoints halt the progress of the cell cycle when:

-there is an abnormal number of chromosomes. -the chromosomal DNA is damaged. -the DNA cannot be repaired. -the chromosomes are not properly aligned during the M phase.

Cells are exposed to 3H-thymidine for a short period and the first labeled mitotic chromosomes appear about 4 hours later. Why do researchers conclude that G2 lasts about 4 hours?

Cells are labeled in the S phase when DNA is replicated, so four hours passed between the end of the S phase and the beginning of the M phase when mitotic chromosomes are first observed.

The Wee1 gene

Produces smaller cells, hence the name "wee."

Daughter cells that result from mitosis

They are genetically identical to one another and to the parent cell.

Leland Hartwell and Ted Weinert proposed that cells possess _______ as part of their cell cycle.

checkpoints

The product of the cdc2 gene is:

cyclin-dependent kinase

Cells that divide only when given an appropriate stimulus include:

liver cells

how is p21 produced

p53 causes transcription and translation of the p21 gene.

When the cyclin concentration _____, cyclin-dependent kinase is activated, causing the cell to _____.

rises; enters the M phase

If a cell in the G2 phase is fused with a cell in the M phase:

the G2 nucleus will enter the M phase.