Chapter 18

The eukaryotic cell cycle is composed of four phases in the following order

• G1; S; G2; M

• G1; G2; S; M

• G1; M; G2; S

• S; G1; G2; M

The length of time it takes for the cells labeled during DNA synthesis to begin to enter mitosis is a good estimate of the length of the _______ phase(s).

• G1

• S

• G2

• M

In a typical cycling mammalian cell, _______ of the cell cycle is spent in interphase.

• 99%

• 95%

• 75%

• 50%

Cell cycles of early embryonic animal cells are unusual because they have

• no G1 or G2

• an elongated G1 and G2

• a short S

• a much shortened M

The number of cells in the different phases of a population can be determined most easily by using a _______ to measure the amount of DNA per cell in a large sample of cells.

• scintillation counter

• flow cytometer

• fluorescence microscope

• phase-contrast microscope after autoradiography

Cells in the quiescent phase of the cell cycle are said to be in the _______ phase.

• G0

• G1

• G2

• M

Which of the following represents the amount of DNA in a typical G2 cell?

• n

• 2n

• 4n

• 8n

What event takes place during interphase?

• Centromeres divide.

• Metabolic processes, such as DNA replication, are carried out by the cell

• Spindle fibers start forming

• Centrioles begin to appear.

Skin fibroblasts near a wound, arrested in G0, are stimulated to enter G1 by _______ growth factor.

• epidermal

• fibroblast

• platelet-derived

• keratinocyte

The oocytes in a normal 7-year-old female (prepubertal) would be expected to be arrested in which stage of the cell cycle, until they are hormonally stimulated?

• G1

• G2

• Interphase

• G0