: used in many laboratories such as

: Tissue culture technology is something that is being applied in many various fields of cell biology. These cell cultures are used in many laboratories such as cytogenetic, biochemical and molecular biology laboratories, especially for the purpose of research. Cell cultures refer to the removal of cells from an animal or plant and their subsequent growth in a favorable artificial environment. The cells may be removed from the tissue directly and disaggregated by enzymatic or mechanical means before they are cultivated. They may also be derived from a cell line that has already been established. Primary culture refers to the stage of the culture after the cells are isolated from the tissue and proliferated under the appropriate conditions until they occupy all of the available substrate (otherwise known as reaching confluence). This is the stage at which cell have to be subcultured by transferring them to a new vessel with fresh growth medium to provide more room for combined growth. After the first subculture, the primary culture becomes known as the cell line. The cells with the highest growth capacity predominates resulting in a degree of genotypic and phenotypic similarity in the population. Cell culture conditions vary for each cell type but the artificial environment in which the cells are cultured consists of a suitable vessel containing a substrate or medium that supplies the essential nutrients (amino acids, carbohydrates, vitamins, minerals, growth factors, hormones, and gases). Also the physiochemical conditions such as pH and temperature have to be regulated. Most cells need to be cultured in solid or semi-solid substrate so that they may adhere to the surface, while others can grow in a medium where they float (this is known as a suspension culture).Cells in culture can be divided into three basic categories based on their shape (morphology): Fibroblastic, Epithelial and lymphoblastic. The basic equipment used in cell cultures include: cell culture hood, incubator, water bath, centrifuge, cell counter, and microscope. Subculturing cells is the procedure in which some of the cells are transferred to growth medium in order to induce propagation of cell lines. A maximum of 80% confluence is desirable for this. After this point, the cells become deprived of nutrients and do not show as much growth. This experiment consisted of using the HELA cell line which is an immortal cell line used widely in scientific research. HELA cells grow well in DMEM which is easy to manipulate the properties of. PBS is a buffer which has a water base salt solution. It has many uses because of the fact that it is isotonic and non-toxic. Trypsin is a serine protease used to cleave proteins bound to the cultured cell to the dish. So the trypsin deattaches the cells from the surface. This detachment can be checked under a microscope. Adherent cells will consist of a different geometric shape due to the fact that it is stuck to a surface, whereas suspended cells will look circular as they are floating without any contact the the surfaces. The counting of cells can be done by the hemocytometer which is a manual way of counting cells. Automated cell counting is also more recently proving to be a more effective and accurate way of counting cells and distinguishing between dead and live cells.