The Cell Cycle: An Overview

->Cell Cycle: well-ordered sequence of events between the time a cell divides to form two daughter cells and the time those daughter cells divide. Includes:

- Doubling of cell's cytoplasm & reproduction of cellular organelles, precise duplication of DNA, mitosis and cytokinesis

- Cell cycle duration varies with type of cell (some 1 hr, others >24 hrs)

- Nerve and muscle cells never or rarely divide once they are formed.

- Cell cycle alternates between M phase, or dividing phase, and Interphase, the nondividing phase.

M phase: shortest part of cell cycle and phase during which cell divides, includes:

1. Mitosis - division of nucleus

2. Cytokinesis - division of the cytoplasm

Interphase: nondividing phase which is about 90% of the cell cycle and includes most of the cell's growth and metabolic activities. Consists of three periods:

1. G1 phase - first growth phase

2. S phase - synthesis phase when DNA is synthesized as chromosomes are replicated

3. G2 phase - second growth phase