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It is the first step of viral replication. Some viruses attach to the cell membrane of the host cell and inject its DNA or RNA into the host to initiate infection. Attachment to a host cell is often achieved by a virus attachment protein that extends from the protein shell (), of a virus.
The cells do not reproduce in synchrony without explicit and continual prompting (as in experiments with stalked bacteria [9]) and their exponential phase growth is often not ever a constant rate, but instead a slowly decaying rate, a constant stochastic response to pressures both to reproduce and to go dormant in the face of declining nutrient ...
How viruses do this depends mainly on the type of nucleic acid DNA or RNA they contain, which is either one or the other but never both. Viruses cannot function or reproduce outside a cell, and are totally dependent on a host cell to survive. Most viruses are species specific, and related viruses typically only infect a narrow range of plants ...
Bacteriophages are viruses that infect bacteria and archaea. [76] They are important in marine ecology: as the infected bacteria burst, carbon compounds are released back into the environment, which stimulates fresh organic growth. Bacteriophages are useful in scientific research because they are harmless to humans and can be studied easily.
Over time, a decrease in virulence in the predominant strain can sometimes be observed. A successful pathogen needs to spread to at least one other host, and lower virulence can result in higher transmission rates under some circumstances. Likewise, genetic resistance against the virus can develop in a host population over time. [2] [29]
Bacteria divide asexually via binary fission; viruses take control of host cells to produce more viruses; Hydras (invertebrates of the order Hydroidea) and yeasts are able to reproduce by budding. These organisms often do not possess different sexes, and they are capable of "splitting" themselves into two or more copies of themselves.
Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. [112] Under optimal conditions, bacteria can grow and divide extremely rapidly, and some bacterial populations can double as quickly as every 17 minutes. [113] In cell division, two identical clone daughter cells are produced. Some bacteria ...
During the lysogenic cycle, the virus genome is incorporated as prophage and a repressor prevents viral replication. Nonetheless, a temperate phage can escape repression to replicate, produce viral particles, and lyse the bacteria. [13] The temperate phage escaping repression would be a disadvantage for the bacteria.