الفهرس 
المقدمةيوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
This study aimed to : The cell division cycle is a series of events that take place in a cell leading to its division and duplication. In unicellular species (no cell nucleus) such as bacteria, cell division occurs by a process called binary fission and produces a new organism. In multicellular species (with a cell nucleus) somatic cell division occurs in two distinct phases: interphase, during which the cell grows and replicates its DNA, followed by mitosis in which the cell divides to produce two daughter cells. This process is also called proliferation. On other hand Human body cells have 46 chromosomes. These are arranged in pairs, with one copy of each chromosome from Mum, and the other from Dad. If your sperm and eggs were made using mitosis, when these two cells fused at fertilisation, the egg would have 96 chromosomes. Definitely not human! Meiosis is the process of cell division that halves the chromosome number and makes gametes (human gametes contain 23 chromosomes). This ensures that at fertilisation the number of chromosomes found in normal body cells - the diploid number - is restored.