5.1 The Cell Cycle

KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions.

5.1 The Cell Cycle

• I can describe the stages of the cell cycle.• I can compare rates of division in different cell types.• I can identify factors that limit cell size.

5.1 The Cell Cycle

The cell cycle has four main stages.

• The cell cycle is a regular pattern of growth, DNA replication, and cell division.

5.1 The Cell Cycle

• The 4 main stages of the cell cycle are gap 1, synthesis, gap 2, and mitosis.

– Gap 1 (G1): cell growth and normal functions

• Mitosis occurs only if the cell is large enough and the DNA undamaged.

– DNA synthesis (S): copies DNA

– Gap 2 (G2): additional growth

– Mitosis (M): includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis)

5.1 The Cell Cycle

Cells divide at different rates.

• The rate of cell division varies with the need for those types of cells.

• Some cells are unlikely to divide (G0).

5.1 The Cell Cycle

Cell size is limited.

• Volume increases faster than surface area.

5.1 The Cell Cycle

• Surface area must allow for adequate exchange of materials.

– Cell growth is coordinated with division.

– Cells that must be large have unique shapes.

5.1 The Cell Cycle

In which stage of the cell cycle do the nucleus and its contents divide?

• A. synthesis• B. gap 1• C. mitosis• D. gap 2

5.1 The Cell Cycle

5.1 The Cell Cycle

During the gap 1 stage of the cell cycle, a cell• a. splits into two new cells.• b. carries out its normal functions.• c. duplicates its DNA.• d. divides its cytoplasm.

5.1 The Cell Cycle

Which of the following phrases best describes cytokinesis?• a. division of the cytoplasm• b. division of the nucleus• c. division of DNA• d. division of surface area

5.1 The Cell Cycle

Which statement is true about the rates of cell division in eukaryotes?

• A. They remain the same for the life of the organism.• b. They are faster than that of prokaryotes.• c. They increase with the age of the organism.• d. They vary greatly within an organism.

5.1 The Cell Cycle

Which of the following limits the maximum size of a cell?• a. the stage of the cell cycle• b. the ratio of cell surface area to volume• c. the number of mitochondria in the cell• d. the size of the organism