SCIENCE|natural and applied sciences|life sciences
- cill fáis Tagairt Faomhadh an téarma seo mar chuid de Thionscadal Lex
- ga
- growing cell
- en
- Sainmhíniú "bacterial cell at the log phase1 of the division cycle21 log phase [ IATE:1075179 ]2 division cycle [ IATE:1544625 ]" Tagairt "COM-Terminology Coordination, based on:""bacteria"". Encyclopædia Britannica. Encyclopædia Britannica Online.Encyclopædia Britannica Inc., 2015. http://www.britannica.com/EBchecked/topic/48203/bacteria/272364/Growth-of-bacterial-populations [30.1.2015]"
- Nóta When bacteria are placed in a medium that provides all of the nutrients that are necessary for their growth, the population exhibits four phases of growth that are representative of a typical bacterial growth curve. Upon inoculation into the new medium, bacteria do not immediately reproduce, and the population size remains constant. During this period, called the lag phase, the cells are metabolically active and increase only in cell size. They are also synthesizing the enzymes and factors needed for cell division and population growth under their new environmental conditions. The population then enters the log phase, in which cell numbers increase in a logarithmic fashion, and each cell generation occurs in the same time interval as the preceding ones, resulting in a balanced increase in the constituents of each cell. The log phase continues until nutrients are depleted or toxic products accumulate, at which time the cell growth rate slows, and some cells may begin to die. Under optimum conditions, the maximum population for some bacterial species at the end of the log phase can reach a density of 10 to 30 billion cells per millilitre.The log phase of bacterial growth is followed by the stationary phase, in which the size of a population of bacteria remains constant, even though some cells continue to divide and others begin to die. The stationary phase is followed by the death phase, in which the death of cells in the population exceeds the formation of new cells. The length of time before the onset of the death phase depends on the species and the medium. Bacteria do not necessarily die even when starved of nutrients, and they can remain viable for long periods of time.