Mitosis (Edexcel IGCSE Biology: Double Science)

• Mitosis is defined as nuclear division giving rise to genetically identical cells
• This type of cell division is used for growth, repair of damaged tissues, replacement of cells and asexual reproduction and is known as mitosis
• 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 cell division by mitosis

Process

• Just before mitosis, each chromosome in the nucleus copies itself exactly (forms x-shaped chromosomes)
• Chromosomes 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