Meiosis (Edexcel IGCSE Biology)

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Meiosis

  • Meiosis is a type of nuclear division that gives rise to cells that are genetically different

  • During meiosis, the number of chromosomes must be halved to form the new cells; these new cells are called gametes (sex cells)

    • We describe gametes as being haploid - having half the normal number of chromosomes

    • There would be double the number of chromosomes after they join at fertilisation in the zygote (fertilized egg) if this did not happen

  • Meiosis is important for

    • The production of gametes e.g. sperm cells and egg cells, pollen grains and ovum

    • Increasing genetic variation of offspring

The process of meiosis

  • Meiosis starts with chromosomes doubling themselves, as in mitosis, and lining up in the centre of the cell

  • After this has happened the cells divide twice so that only one copy of each chromosome passes to each gamete

    • First division: chromosomes pair up along the centre of the cell, then cell fibres will pull the pairs apart, and each new cell will have one chromosome pair

    • Second division: chromosomes will line up along the centre of these cells, and cell fibres will pull them apart 

  • A total of four haploid daughter cells will be produced, these are the gametes

Meiosis, IGCSE & GCSE Biology revision notes

The process of cell division by meiosis to produce haploid gamete cells

Comparing Mitosis & Meiosis

Comparing Mitosis & Meiosis Table

Examiner Tips and Tricks

Questions on cell division often ask for differences between mitosis and meiosis. Learn two or three and remember to BE SPECIFIC when giving your answer.You should also know the reasons for a specific type of cell division taking place and the types of cells where each happen.

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Lára Marie McIvor

Author: Lára Marie McIvor

Expertise: Biology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.