Cell Cycle

• Cells reproduce through a continuous sequence of growth and division known as the cell cycle.

• The cell cycle consists of two main stages: growth stage and division stage.

• In the growth stage (interphase), the cell makes new molecules and DNA is replicated.

  • Interphase has three parts: G1 (metabolic activities), S (DNA replication), and G2 (preparation for division).

• The division stage involves mitosis (division of the cell's nucleus) and cell division (division of the cytoplasm).

• Different types of cells spend different relative lengths of time in the phases of the cell cycle.

Errors in the Cell Cycle

• Mutations can disrupt the mitotic process and cause permanent changes in the DNA molecule.

• Mutations can be caused by mutagens like toxic compounds, radiation, or viruses.

• Mutations can be copied during DNA replication and passed on to daughter cells.

• Mutations can lead to localized groups of cells with mutations, rather than affecting every cell in the body.

• Certain genes regulate the rate of mitosis and can be affected by mutations.

• Mutations can activate genes that promote uncontrolled cell division (oncogenes).

• Examples of mutations leading to cancer include retinoblastoma, Wilms tumor, and breast cancer.