Spores are able to survive the harsh conditions of the death phase and become growing bacteria when placed in an environment that supports life. 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.
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. They may share certain morphological and physiological characteristics with animals or plants or both. 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. protist, any member of a group of diverse eukaryotic, predominantly unicellular microscopic organisms.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.Starfish, however, are also capable of sexual reproduction. A new starfish can develop from a single ray, or arm. Starfish, like the one in Figure below, reproduce this way. Fragmentation occurs when a parent organism breaks into fragments, or pieces, and each fragment develops into a new organism.Binary fission occurs when a parent cell splits into two identical daughter cells of the same size.They include binary fission, fragmentation, and budding. There are several different methods of asexual reproduction.
All prokaryotes and some eukaryotes reproduce this way. It results in offspring that are genetically identical to each other and to the parent. There are two basic types of reproduction: asexual reproduction and sexual reproduction.Īsexual reproduction involves a single parent. It is one of the defining characteristics of living things. Reproduction is the process by which organisms give rise to offspring. Children resemble their parents, but they are never identical to them. Instead, each has a unique combination of characteristics inherited from both parents.įamily Portrait: Mother, Daughter, Father, and Son. The children resemble their parents, but they are not identical to them. In many other organisms, two parents are involved, and the offspring are not identical to the parents.
The parent cell simply divides to form two daughter cells that are identical to the parent. For many single-celled organisms, reproduction is a similar process. It is also how many organisms produce offspring. \)Ĭell division is how organisms grow and repair themselves.
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