FACTORS THAT AFFECT MITOSIS

=Factors that Affect Mitosis= ===Growth & Repair=== [image:http://i.imgur.com/FQ3Lrbz.jpg?3] After an injury many cells are replaced in order to repair the damage. The rate of mitosis must increase in order to produce these new cells. Similarly the rate of mitosis also increases during periods of growth, such as our development in the womb, childhood and puberty. In pants there is also much higher rates of mitosis during germination and growth. ===Nutrient availability=== [image:http://i.imgur.com/xImSgOE.png?1] Nutrients are needed as a source of energy and as building blocks. Cell will need DNA nucleotides in order to synthesise new DNA and the cell organelles will have to be copied too. A lack of necessary nutrients can restrict or stop mitosis. This is why people in areas of famine are often smaller and shorter. ===Cell Type & Location=== [image:http://i.imgur.com/xSf3p03.jpg?1] Body tissues that are replaced frequently have a higher rate of mitosis. For example bone marrow which is responsible for blood cell production is an area in the body where rapid mitosis occurs. Skin cells, hair follicles and the cells lining our intestines (epithelial cells) all have high rates of mitosis as these tissues constantly need to be replaced. In plants growth occurs largely at the shoot and root tips. These cells have much higher rates of mitosis than the rest of the plant. Damaged tissues are not simply replaced by surrounding cells. Special '''stem cells''' do this. Stem cells are undifferentiated cells, this means that they have not fully developed into a specific cell type and can divide to produce different cell types. During growth or repair stem cells undergo mitosis and cell division to produce more of whatever cell type is required. Stem cells have special mechanisms that allows them to divide many more times than regular cells. ===Enzyme Activity=== [image:http://i.imgur.com/eNGFURg.png?1] DNA replication, mitosis and cell division are controlled by an array of proteins and enzymes. Therefore the factors that affect enzymes can also affect mitosis. Some of the key factors that affect enzyme activity include: • Temperature • pH • Substrate concentration (e.g. the availability of nutrient building blocks) • Enzyme Cofactors (some dietary vitamins are essential for enzyme function) ^For further details see ''ENZYMES ACTIVITY -FACTORS''^ ==Regulation== The cell cycle, including growth, DNA replication, mitosis and cell division are all highly regulated processes that are regulated by special genes within a cell. Mutations in these genes can result in a loss of regulation and may cause a larger number of these cells to grow. This causes a lump known as a tumour [image:http://i.imgur.com/uvLpGLB.jpg?1] Patients undergoing chemotherapy often lose their hair, feel nauseous and may need a bone-marrow transplant. This is because chemotherapy drugs target cells with higher mitosis / division rates such as tumour cells. However, the side effect is that it also affects body cells that normally have a higher rate of mitosis / division.