Science - Grade 10 Biology - The Cell Cycle

The cell cycle

The life of a cell in which it is born, grows, reproduces, and dies.

The two main stages in the cell cycle

1)Interphase 2)Mitosis and cytokinesis

Interphase

The growth stage - 90%

Mitosis and cytokinesis

The division stage - 10%

Somatic cells

Non-reproductive body cells

Why do cells reproduce by mitosis? (three reasons)

Growth, repair, replacement

Interphase occurs...

Before mitosis begins

The first stage of interphase

G1 (first growth) - 20%

The second stage of interphase

S (synthesis) - 50%

The third stage of interphase

G2 (second growth) - 20%

The first step in mitosis

Prophase

Prophase

- DNA condenses (chromatin forms chromosome)
- Centrioles move to opposite ends of the cell
- Nuclear membrane dissolves

The second step in mitosis

Metaphase

Metaphase

- Chromosomes line up in the center of the cell
- Spindle fibers attach to the centromere of each chromosome

The third step in mitosis

Anaphase

Anaphase

- Chromosomes split apart at the centromere (now daughter chromosomes)
- They are pulled to opposite ends of the cell by spindle fibers

The fourth step in mitosis

Telophase

Telophase

- Daughter chromosomes decondense back into chromatin
- Nuclear membranes form
- Cells begin to split

Occurs after mitosis

Cytokinesis

Cytokinesis

- Division of organelles and cytoplasm
- Cell membrane pinches, splitting in two
- Plants (cell plate) animals (cleavage furrow)