GCSE Biology · Edexcel 1BI0 · Topic 3B
Meiosis
Key points
- Meiosis is cell division that makes gametes. It happens in the reproductive organs (testes and ovaries in humans).
- The DNA is copied, then the cell divides twice, giving four daughter cells.
- Each gamete is haploid: it has one set of chromosomes (23 in humans), half the diploid number (46).
- The gametes are genetically different from each other and from the parent cell.
- At fertilisation two haploid gametes join to form a diploid zygote, which then divides by mitosis to form an embryo.
- Compare with mitosis: mitosis gives two identical diploid cells; meiosis gives four varied haploid cells.
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Meiosis is the special cell division that makes gametes. It halves the number of chromosomes and shuffles the genetic information, so every gamete is different. This sub-topic explains what happens and why it matters.
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