![]() ![]() This method of division generally occurs in Flagellates, such as Euglena. This is where the cell's cytoplasm is separated longitudinally. This is where the cytoplasm is separated along the cell's longitudinal axis. This division can be seen in Paramecium, a ciliated protozoan. This type can be found in organisms such as amoebas.Ĭytokinesis occurs along the cell's transverse axis in transverse binary fission. It is most typically perpendicular to the plane of chromosome division (karyokinesis). It must be able to reproduce at the right time, in the right place, and give each offspring a complete copy of its important genetic material to stay alive and compete.īinary fission has four forms based on the cytoplasmic division plane.Ĭytoplasm division (cytokinesis) can occur in any plane in this situation. Many prokaryotes, including archaea, cyanobacteria, eubacteria, and certain eukaryotes like amoeba and Paramecium, reproduce by binary fission.īinary fission occurs in some cell organelles, like mitochondria. In this asexual method of reproduction, the daughter cells produced have the same genetic material as their parents. This process does not involve the formation or fusion of gametes, hence it is referred to as asexual reproduction. It is capable of producing only two components from a single entity. Thereafter, each of which has the potential to expand to the size of the original cell or organelle.īinary fission differs from other forms of fission. The single living cell or organelle doubles in size before splitting into two identical daughter cells. Spores are able to survive the harsh conditions of the death phase and become growing bacteria when placed in an environment that supports life.Binary fission is an asexual way to reproduce. This helps spore producing bacteria to survive long enough for spore production. ![]() As dying cells lyse or break open, they spill their contents into the environment making these nutrients available to other bacteria. In the death phase, the number of living cells decreases exponentially and population growth experiences a sharp decline. Death Phase: As nutrients become less available and waste products increase, the number of dying cells continues to rise.Spore forming bacteria produce endospores in this phase and pathogenic bacteria begin to generate substances (virulence factors) that help them survive harsh conditions and consequently cause disease. Under the less favorable conditions, competition for nutrients increases and the cells become less metabolically active. This results in no overall population growth. Bacterial cell growth reaches a plateau, or stationary phase, where the number of dividing cells equal the number of dying cells. Stationary Phase: Eventually, the population growth experienced in the log phase begins to decline as the available nutrients become depleted and waste products start to accumulate.It is in this growth phase that antibiotics and disinfectants are most effective as these substances typically target bacteria cell walls or the protein synthesis processes of DNA transcription and RNA translation. Metabolic activity is high as DNA, RNA, cell wall components, and other substances necessary for growth are generated for division. This is the time when the cells are dividing by binary fission and doubling in numbers after each generation time. Exponential (Log) Phase: After the lag phase, bacterial cells enter the exponential or log phase.These cells increase in size, but no cell division occurs in the phase. A small group of cells are placed in a nutrient rich medium that allows them to synthesize proteins and other molecules necessary for replication. Lag Phase: This initial phase is characterized by cellular activity but not growth.A bacterial population's generation time, or time it takes for a population to double, varies between species and depends on how well growth requirements are met. Additional factors include osmotic pressure, atmospheric pressure, and moisture availability. Factors such as oxygen, pH, temperature, and light influence microbial growth. The death phase is characterized by an exponential decrease in the number of living cells.īacteria require certain conditions for growth, and these conditions are not the same for all bacteria.In the stationary phase, growth reaches a plateau as the number of dying cells equals the number of dividing cells.The exponential or log phase is a time of exponential growth.The initial phase is the lag phase where bacteria are metabolically active but not dividing.There are four distinct phases of the growth curve: lag, exponential (log), stationary, and death.The bacterial growth curve represents the number of live cells in a bacterial population over a period of time. ![]()
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