Human Cells: Cell Division and Differentation

Any cell in the body other than the cells involved in reproduction They are diploid and divide by mitosis to form more somatic cells, this maintains the diploid chromosome number Diploid cells meaning they have 23 pairs of homologous chromosomes and 46b chromosomes in total

It is important to ensure that no genetic information is lost or duplicated and that each daughter cell contains all of the characteristics of its species

Germline cells are gametes (sperm and ova) and the stem cells that divide to form haploid gametes found in the ovaries and testes They divide by mitosis and meiosis

When they divide by mitosis they produce more germline cells, maintaining the diploid chromosome number When the nucleus of a germline stem cell divides by meiosis they produce haploid gametes. It undergoes two divisions firstly homologous chromosomes are separated and secondly chromatids are separated

The process by which a cell expresses certain genes to produce proteins characteristic for that type of cell. This allows them to carry out specialised functions

Embryonic and tissue

Cells in the very early embryo that can differentiate into all the cell types that make up the individual, they are said to be pluripotent All the genes in embryonic stem cells can be switched on meaning they can differentiate into any type of cell

Tissue stem cells are involved in the growth, repair and renewal of the cells found in particular tissues. They are said to be multipotent as they can differentiate into all of the cell types found in a particular tissue type For example blood stem cells located in bone marrow can give rise to re blood cells, platelets, phagocytes and lymphocytes

Therapeutic uses involve the repair of damaged or diseased organs or tissues For example they are used in corneal repair or the regeneration of damaged skin

Research use involves stem cells being used as model cells to study how diseases develop or being used for drug testing Stem cell research also provides information on how cells processes work such as cell growth, differentiation and gene regulation work

Stem cells from the embryo can self renew under the right conditions in the lab

The use of embryonic stem cells can offer effective treatment for diseases and injury however it involves the destruction of embryos

Cancer cells divide excessively because they do not respond to regulatory signals. This results in a mass of abnormal cells called a tumour

Cells within the tumour may fail to attach to eachother, spreading through the body forming a secondary tumour