Lysogenic cycle

process of virus reproduction in which the bacteriophage DNA is integrated into the host bacteria ‘s genome
not to be confused with Lytic cycle lysogenic cycle, compared to lytic cycle lysogenic Cycle:1. The prokaryotic cell is shown with its deoxyribonucleic acid, in green. 2. The bacteriophage attaches and releases its deoxyribonucleic acid, shown in red, into the prokaryotic cellular telephone. 3. The bacteriophage DNA then moves through the cell to the host ’ sulfur DNA. 4. The bacteriophage deoxyribonucleic acid integrates itself into the host cell ‘s DNA, creating prophage. 5. The prophage then remains dormant until the master of ceremonies cell divides. 6. After the host cell has divided, the bacteriophage deoxyribonucleic acid in the daughter cells activate, and the bacteriophage deoxyribonucleic acid begins to express itself. Some of the cells containing the prophage go on to create new phages which will move on to infect early cells.

Bạn đang đọc: Lysogenic cycle

Lysogeny, or the lysogenic cycle, is one of two cycles of viral reproduction ( the lytic cycle being the other ). Lysogeny is characterized by consolidation of the bacteriophage nucleic acid into the server bacteria ‘s genome or formation of a round replicon in the bacterial cytoplasm. In this condition the bacteria continues to live and reproduce normally. The genic corporeal of the bacteriophage, called a prophage, can be transmitted to daughter cells at each subsequent cellular telephone division, and subsequently events ( such as UV radiotherapy or the presence of certain chemicals ) can release it, causing proliferation of new phages via the lytic cycle. [ 1 ] Lysogenic cycles can besides occur in eukaryotes, although the method acting of DNA internalization is not fully understand. The difference between lysogenic and lytic cycles is that, in lysogenic cycles, the go around of the viral deoxyribonucleic acid occurs through the usual prokaryotic reproduction, whereas a lytic cycle is more immediate in that it results in many copies of the virus being created very cursorily and the cell is destroyed. One key dispute between the lytic cycle and the lysogenic cycle is that the last matchless does not lyse the host cellular telephone square away. [ 2 ] Phages that replicate lone via the lytic bicycle are known as acerb phages while phages that replicate using both lytic and lysogenic cycles are known as temperate phages. [ 1 ] In the lysogenic cycle, the bacteriophage DNA first gear integrates into the bacterial chromosome to produce the prophage. When the bacteria reproduces, the prophage is besides copied and is present in each of the daughter cells. The daughter cells can continue to replicate with the prophage present or the prophage can exit the bacterial chromosome to initiate the lytic hertz. [ 1 ] In the lysogenic cycle the host DNA is not hydrolyzed but in the lytic cycle the host DNA is hydrolyzed in the lytic phase .

See also  Truvia: Good or Bad?

Bacteriophages [edit ]

Bacteriophages are viruses that infect and retroflex within a bacteria. Temperate phages ( such as lambda bacteriophage ) can reproduce using both the lytic and the lysogenic bicycle. Via the lysogenic hertz, the bacteriophage ‘s genome is not expressed and is rather integrated into the bacteria ‘s genome to form the prophage. [ 3 ] Since the bacteriophage ‘s genetic information is incorporated into the bacteria ‘s genetic information as a prophage, the bacteriophage replicates passively as the bacteria divides to form daughter bacteria cells. [ 3 ] In this scenario, the daughter bacteria cells contain prophage and are known as lysogens. Lysogens can remain in the lysogenic cycle for many generations but can switch to the lytic cycle at any clock time via a serve known as evocation. [ 3 ] During induction, prophage deoxyribonucleic acid is excised from the bacterial genome and is transcribed and translated to make coat proteins for the virus and regulate lytic growth. [ 3 ]
The model organism for studying lysogeny is the lambda bacteriophage. Prophage integration, care of lysogeny, trigger, and restraint of bacteriophage genome excommunication in generalization is described in detail in the lambda bacteriophage article .

See also  Emergency Medical Technician (EMT) vs. Paramedic

Fitness tradeoffs for bacteria [edit ]

Bacteriophages are parasitic because they infect their hosts, use bacterial machinery to replicate, and ultimately lyse the bacteria. Temperate phages can lead to both advantages and disadvantages for their hosts via the lysogenic cycle. During the lysogenic cycle, the virus genome is incorporated as prophage and a repressor prevents viral replication. Nonetheless, a moderate bacteriophage can escape repression to replicate, produce viral particles, and lyse the bacteria. [ 5 ] The temperate bacteriophage escaping repression would be a disadvantage for the bacteria. On the other pass, the prophage may transfer genes that enhance host virulence and resistance to the immune system. besides, the repressor produced by the prophage that prevents prophage genes from being expressed confers immunity for the master of ceremonies bacteria from lytic infection by relate viruses. [ 5 ]

Another organization, arbitrium, has recently been described for bacteriophages infecting respective Bacillus species, in which the decision between lysis and lysogeny is transmitted between bacteria by a peptide divisor. [ 6 ] [ 7 ]

lysogenic conversion [edit ]

In some interactions between lysogenic phages and bacteria, the lysogenic conversion may occur, which can besides be called bacteriophage conversion. It is when a temperate bacteriophage induces a change in the phenotype of the infect bacteria that is not share of a usual bacteriophage cycle. Changes can frequently involve the external membrane of the cell by making it impervious to other phages or evening by increasing the infective capability of the bacteria for a server. In this direction, moderate bacteriophages besides play a character in the ranch of virulence factors, such as exotoxins and exoenzymes, amongst bacteria. This change then stays in the genome of the infect bacteria and is copied and passed down to daughter cells .

See also  Difference Between Short Run and Long Run Production Function (with Comparison Chart)

bacterial survival [edit ]

lysogenic conversion has shown to enable biofilm formation in Bacillus anthracis [ 8 ] Strains of B. anthracis cured of all bacteriophage were unable to form biofilms, which are surface-adhered bacterial communities that enable bacteria to better access nutrients and survive environmental stresses. [ 9 ] In addition to biofilm formation in B. anthracis, lysogenic conversion of Bacillus subtilis, Bacillus thuringiensis, and Bacillus cereus has shown an enhance rate or extent of monogenesis. [ 8 ] Sporulation produces endospores, which are metabolically dormant forms of the bacteria that are highly resistant to temperature, ionizing radiation, dehydration, antibiotics, and disinfectants. [ 8 ]

bacterial virulence [edit ]

Non-virulent bacteria have besides been shown to transform into highly acerb pathogens through lysogenic conversion with the virulence factors carried on the lysogenic prophage. [ 10 ] Virulence genes carried within prophages as discrete autonomous genic elements, known as morons, confer an advantage to the bacteria that indirectly benefits the virus through enhance lysogen survival. [ 8 ]

Examples :

Preventing lysogenic generalization [edit ]

Strategies to combat certain bacterial infections by blocking prophage generalization ( the transition from the lytic hertz to the lysogenic cycle ) by eliminating in vivo initiation agents have been proposed. [ 10 ] Reactive oxygen species ( ROS ), such as hydrogen hydrogen peroxide, are hard oxidizing agents that can decompose into complimentary radicals and campaign DNA price to bacteria, which lead to prophage initiation. [ 10 ] One electric potential strategy to combat prophage induction is through the use of glutathione, a impregnable antioxidant that can remove free group intermediates. [ 10 ] Another approach could be to cause overexpression of CI repressor since prophage induction merely occurs when the assiduity of CI repressor is besides low. [ 10 ]

References [edit ]