Cell Cycle and Cell Division

Lesson

Part 1 — how a cell prepares for division and how mitosis shares out its chromosomes.

In this lesson you will

Describe the phases of the cell cycle and the events of G1, S, G2 and M
Describe the stages of mitosis and cytokinesis in animal and plant cells
Explain the significance of mitosis

Concept

The cell cycle

The cell cycle is the sequence of events by which a cell duplicates its genome, synthesises other constituents and divides into two daughter cells. It has two parts: interphase and the M phase (mitosis).

Concept

Interphase: G one, S and G two

Interphase is the time between two M phases. Cell growth and DNA replication happen in an orderly sequence.

Table of the events of G1, S and G2 with DNA content and chromosome number
Phase	What happens	DNA and chromosomes
G1 (gap 1)	Cell is metabolically active and grows; no DNA replication	2C DNA; 2n chromosomes
S (synthesis)	DNA replicates; in animal cells the centriole duplicates in the cytoplasm	DNA rises from 2C to 4C; chromosome number stays 2n
G2 (gap 2)	Proteins for mitosis are made; growth continues	4C DNA; 2n chromosomes

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