Growth and ReproductionFurther information: Bacterial growth
Unlike in multicellular organisms, increases in cell size (cell growth and reproduction by cell division) are tightly linked in unicellular organisms. Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. Under optimal conditions, bacteria can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9.8 minutes. In cell division, two identical clone daughter cells are produced. Some bacteria, while still reproducing asexually, form more complex reproductive structures that help disperse the newly formed daughter cells. Examples include fruiting body formation by Myxobacteria and aerial hyphae formation by Streptomyces, or budding. Budding involves a cell forming a protrusion that breaks away and produces a daughter cell.
In the laboratory, bacteria are usually grown using solid or liquid media. Solid growth media such as agar plates are used to isolate pure cultures of a bacterial strain. However, liquid growth media are used when measurement of growth or large volumes of cells are required. Growth in stirred liquid media occurs as an even cell suspension, making the cultures easy to divide and transfer, although isolating single bacteria from liquid media is difficult. The use of selective media (media with specific nutrients added or deficient, or with antibiotics added) can help identify specific organisms.
Most laboratory techniques for growing bacteria use high levels of nutrients to produce large amounts of cells cheaply and quickly. However, in natural environments nutrients are limited, meaning that bacteria cannot continue to reproduce indefinitely. This nutrient limitation has led the evolution of different growth strategies (see r/K selection theory). Some organisms can grow extremely rapidly when nutrients become available, such as the formation of algal (and cyanobacterial) blooms that often occur in lakes during the summer. Other organisms have adaptations to harsh environments, such as the production of multiple antibiotics by Streptomyces that inhibit the growth of competing microorganisms. In nature, many organisms live in communities (e.g., biofilms) that may allow for increased supply of nutrients and protection from environmental stresses. These relationships can be essential for growth of a particular organism or group of organisms (syntrophy).
Bacterial growth follows three phases. When a population of bacteria first enter a high-nutrient environment that allows growth, the cells need to adapt to their new environment. The first phase of growth is the lag phase, a period of slow growth when the cells are adapting to the high-nutrient environment and preparing for fast growth. The lag phase has high biosynthesis rates, as proteins necessary for rapid growth are produced. The second phase of growth is the logarithmic phase (log phase), also known as the exponential phase. The log phase is marked by rapid exponential growth. The rate at which cells grow during this phase is known as the growth rate (k), and the time it takes the cells to double is known as the generation time (g). During log phase, nutrients are metabolised at maximum speed until one of the nutrients is depleted and starts limiting growth. The final phase of growth is the stationary phase and is caused by depleted nutrients. The cells reduce their metabolic activity and consume non-essential cellular proteins. The stationary phase is a transition from rapid growth to a stress response state and there is increased expression of genes involved in DNA repair, antioxidant metabolism and nutrient transport.
Read more about this topic: Bacteria
Other articles related to "growth and reproduction, growth, reproduction":
... mammoth can be determined by counting the growth rings of its tusks, if viewed in cross section ... The growth rate of the tusks slowed down when it became harder to forage, for example during disease, when a male was banished from the herd, and during periods of severe ...
... economy of Chhattisgarh has grown rapidly in recent years with a growth rate of 11.49 per cent in GDP for 2009–2010 ... Chhattisgarh’s success factors in achieving high growth rate are growth in agriculture and industrial production ...
... The concept of "Smart Growth" has emerged in the last 10–20 years driven by "new guard" urban planners, innovative architects, visionary developers, community activists, and ... Smart Growth is a term which has become codified in Federal and State regulations ... variations of the same concept with different emphasis, including Smart Growth New Urbanism New Community Design Sustainable Development Traditional ...
... Smart growth is an urban planning and transportation theory that concentrates growth in compact walkable urban centers to avoid sprawl ... The term 'smart growth' is particularly used in North America ... Smart growth values long-range, regional considerations of sustainability over a short-term focus ...
... reproduces mostly vegetatively, because its possibilities of generative reproduction are very limited by the climatic conditions of its location ...
Famous quotes containing the words reproduction and/or growth:
“Were I called on to define, very briefly, the term Art, I should call it the reproduction of what the Senses perceive in Nature through the veil of the soul. The mere imitation, however accurate, of what is in Nature, entitles no man to the sacred name of Artist.”
—Edgar Allan Poe (18091845)
“Interpretation is the evidence of growth and knowledge, the latter through sorrow that great teacher.”
—Eleonora Duse (18581924)