Cell DivisionEdexcel GCSE Biology: Revision notes
Section 1
What Happens During the Cell Cycle?
The cell cycle has three stages:
- Interphase — the cell grows, replicates DNA (each chromosome becomes two sister chromatids), and produces new organelles.
- Mitosis — the nucleus divides.
- Cytokinesis — the cytoplasm and cell membrane divide, forming two daughter cells.
DNA replication happens in interphase, before mitosis begins.
Section 2
The Stages of Mitosis
| Stage | What happens |
|---|---|
| Prophase | Chromosomes condense; nuclear envelope breaks down |
| Metaphase | Chromosomes line up at the equator |
| Anaphase | Sister chromatids pulled to opposite poles |
| Telophase | Nuclear envelope re-forms around each set |
Then cytokinesis splits the cytoplasm into two daughter cells.
Mnemonic IPMAT: Interphase, Prophase, Metaphase, Anaphase, Telophase.
Section 3
What Do Mitosis's Products Look Like?
Mitosis produces two daughter cells, each genetically identical diploid cells with the same chromosome set as the parent.
Do not confuse with meiosis, which produces genetically different haploid gametes.
Section 4
Why Is Mitosis Important?
Mitosis is essential for:
- Growth — increases cell number
- Repair — replaces damaged cells
- Asexual reproduction — produces genetically identical offspring
A cut heals because mitosis produces new skin cells identical to surrounding tissue.
Section 5
How Does Cancer Relate to Cell Division?
Cancer results from changes in cells causing uncontrolled mitosis, forming a mass of abnormal cells known as a tumour.
Always link cancer explicitly to 'uncontrolled cell division'.
Must Know
- Cell cycle: interphase (DNA replication), mitosis (prophase, metaphase, anaphase, telophase), cytokinesis.
- Mitosis produces two genetically identical diploid daughter cells.
- Important for growth, repair, asexual reproduction.
- Cancer = uncontrolled cell division forming a tumour.
That's the notes covered.
Carry on to the next subtopic.