Cell Division

- in body cells, chromosomes are found in pairs

- body cells divide in a series of stages called the cell cycle

- during the cell cycle the genetic material is doubled then divides inot 2 identical nuclei in a process called mitosis

- before a cell can divide it needs to grow, replicate the DNA to form 2 copies of each chromosome and increase the number of sub cellular structures

- in mitosis 1 set of chromosomes is pulled to each end of the cell and the nucleus divide, finally cytoplasm and cell membranes divide to form 2 identical cells

- mitotic cell division is important in the growth, repair and development of multi cellular organisms

- in plant cells mitosis takes place throughout the life in the meristems found in the shoot and root tubes

- many types of plant cells retain the ability to differentiate throughout life

- most types of animal cells differentiate an early stage of development

- embryonic stem cells (from human embryos) and adult stem cells (from adult bone marrow) can be cloned and made to differentiate into many different types of cells

-treatment with stem cells may be able to help conditions such as paralysis and diabetes

- stem cells from plant meristems are used to produce new plant clones quickly and economically for research, horticulture and agriculture

- treatment with stem cells from embryos or adult cell cloning may be able to help with conditions, such as diabetes

- in theropeutic cloning, an embryo is produced with the same genes as the the patient so the stem cells produced are not rejected and may be used for medical treatment

- use of stem cells has some potential risks and some people have ethical or religious objections