Chapter 14 Practice (305)

Cels 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.

Cells that divide only when given an appropriate stimulus include:

Liver cells.

What is true regarding the Wee1 gene. (3)

Produces smaller cells, hence the name "wee."

DNA synthesis occurs during which phase of the cell cycle?

S phase.

What is true about the daughter cells that result from mitosis? (1)

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

Leland Hartwell and Ted Weinert proposed that cells process ________ as part of their cell cycle.

checkpoints

The product of the cdc2 gene is:

cyclin-dependent kinase.

p21 is:

produced when p53 causes transcription and translation of the p21 gene.

When the cyclin concentration ______, cyclin-dependent kinase is acivated, causing the cell to ______.

rises; enter the M phase

Checkpoints halt the progress of he cell cycle when

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

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

the G2 nucleus will enter the M phase.