Section 5-1 Cell Cycle Section 5-1 Cell Cycle Write everything that is underlined.

Section 5-1Section 5-1“Cell Cycle“Cell Cycle””

Write everything that isWrite everything that is underlinedunderlined

5.1 The Cell Cycle

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

5.1 The Cell Cycle

The cell cycle has four main stagesThe cell cycle has four main stages

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

5.1 The Cell Cycle

• The main stages of the cell cycle are gap The main stages of the cell cycle are gap 1, synthesis, gap 2, and mitosis1, synthesis, gap 2, and mitosis– Gap 1 (GGap 1 (G11): cell growth ): cell growth

and normal functionsand normal functions– DNA synthesis (S): DNA synthesis (S):

copies DNAcopies DNA– Gap 2 (GGap 2 (G22): additional ): additional

growthgrowth– Mitosis (M): includes Mitosis (M): includes

division of the cell division of the cell nucleus (mitosis) andnucleus (mitosis) and division of the cell division of the cell cytoplasm (cytokinesis)cytoplasm (cytokinesis)

5.1 The Cell Cycle

• Mitosis occurs only if:Mitosis occurs only if:–the cell is large enough the cell is large enough –and the DNA is and the DNA is undamagedundamaged

• If the DNA is damaged, the If the DNA is damaged, the cell commits suicide – so cell commits suicide – so it doesn’t pass on bad it doesn’t pass on bad DNADNA

5.1 The Cell Cycle

Cells divide at different rates.Cells divide at different rates.

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

• Some cells are unlikely to divide (GSome cells are unlikely to divide (G00).).

5.1 The Cell Cycle

Why divide? Cell size is limitedWhy divide? Cell size is limited..• Volume increases faster than Volume increases faster than

surface areasurface area

5.1 The Cell Cycle

• Surface area must be big Surface area must be big enough to allow for adequate enough to allow for adequate exchange of materials exchange of materials (nutrients, wastes)(nutrients, wastes)

–Cells that must be large Cells that must be large have unique shapeshave unique shapes