Mitosis (Edexcel IGCSE Biology: Double Science)

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Mitosis

  • Mitosis is defined as nuclear division giving rise to genetically identical cells
  • Mitosis is used for:
    • growth
    • repair of damaged tissues
    • replacement of cells
    • asexual reproduction 
  • Most body cells have two copies of each chromosome
  • We describe these cells as diploid
  • When cells divide their chromosomes double beforehand (also known as duplication)
  • This ensures that when the cell splits in two, each new cell still has two copies of each chromosome (is still diploid)

The process of mitosis

  • Just before mitosis, each chromosome in the nucleus copies itself exactly (forms X-shaped chromosomes)
  • Chromosomes then line up along the centre of the cell where cell fibres pull them apart
  • The cell divides into two; each new cell has a copy of each of the chromosomes

Mitosis, IGCSE & GCSE Biology revision notes

The process of cell division by mitosis

Importance of Mitosis

  • All cells in the body (excluding gametes) are produced by mitosis of the zygote
  • Mitosis occurs during:
    • Growth: mitosis produces new cells
    • Repair: to replace damaged or dead cells
    • Asexual reproduction: mitosis produces offspring that are genetically identical to the parent
  • Mitosis is important for replacing cells e.g, skin cells, and red blood cells, and for allowing growth (production of new cells e.g. when a zygote divides to form an embryo)

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Lára

Author: Lára

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.