1. Genes and Cell Division: Cell Cycle
Chapter 5 Lesson 5A Part 1

2. Objectives:
I will be able to describe the cell cycle and what happens in each stage.

3. The Cell Cycle
Most cells in an organism go through a cycle of growth, development, and division called the cell cycle.

4. The Cell Cycle
Through the cell cycle, organisms grow, develop, replace old or damaged cells, and produce new cells.

5. The Cell Cycle
There are two main phases in the cell cycle—interphase and the mitotic phase.

6. Interphase
Interphase is the period during the cell cycle of a cell’s growth and development Most of the cells life is in interphase. During interphase, most cells go through 3 stages:
Rapid growth and replication, or copying of the membrane-bound structures called organelles.
Copying of DNA, the genetic information in a cell
Preparation for cell division

7. Interphase Interphase occurs in three stages: G1, S, and G2.
G1 and G2 stand for "first Gap" and "second Gap." Interphase begins with G1. This is the long period of time following mitosis but before DNA synthesis (S phase).

8. Interphase
G1 phase: The period prior to the synthesis of DNA. In this phase, the cell increases in mass in preparation for cell division. Note that the G in G1 represents gap and the 1 represents first, so the G1 phase is the first gap phase.
S phase: The period during which DNA is synthesized. In most cells, there is a narrow window of time during which DNA is synthesized. Note that the S represents synthesis.
G1 and G2 stand for "first Gap" and "second Gap." Interphase begins with G1. This is the long period of time following mitosis but before DNA synthesis (S phase).

9. Interphase
G2 phase: The period after DNA synthesis has occurred but prior to the start of cell division. The cell synthesizes proteins and continues to increase in size. Note that the G in G2 represents gap and the 2 represents second, so the G2 phase is the second gap phase.
G1 and G2 stand for "first Gap" and "second Gap." Interphase begins with G1. This is the long period of time following mitosis but before DNA synthesis (S phase).

10. The length of the cell cycle varies depending on the type of cell.
Length of a Cell Cycle
The length of the cell cycle varies depending on the type of cell.