Lysogen
Encyclopedia
A lysogen or lysogenic phage is a phage
that can exist as a prophage
within its host organism. A prophage is the phage DNA in its dormant state, and is either integrated into the host bacteria
's chromosome
or more rarely exists as a stable plasmid
within the host cell. The prophage expresses gene(s) that repress the phage's lytic
action, and the phage enters the lytic cycle
when this suppression is disrupted. Currently a variety of studies are being conducted to see whether other genes are active during lysogeny, examples of which include phage-encoded tRNA and virulence genes.
Alternatively, lysogen can refer to a strain of bacterium that carries a prophage
.
Bacteriophage
A bacteriophage is any one of a number of viruses that infect bacteria. They do this by injecting genetic material, which they carry enclosed in an outer protein capsid...
that can exist as a prophage
Prophage
A prophage is a phage genome inserted and integrated into the circular bacterial DNA chromosome. A prophage, also known as a temperate phage, is any virus in the lysogenic cycle; it is integrated into the host chromosome or exists as an extrachromosomal plasmid. Technically, a virus may be called...
within its host organism. A prophage is the phage DNA in its dormant state, and is either integrated into the host bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
's chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
or more rarely exists as a stable plasmid
Plasmid
In microbiology and genetics, a plasmid is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA. They are double-stranded and, in many cases, circular...
within the host cell. The prophage expresses gene(s) that repress the phage's lytic
Lysis
Lysis refers to the breaking down of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a "lysate"....
action, and the phage enters the lytic cycle
Lytic cycle
The lytic cycle is one of the two cycles of viral reproduction, the other being the lysogenic cycle. The lytic cycle is typically considered the main method of viral replication, since it results in the destruction of the infected cell...
when this suppression is disrupted. Currently a variety of studies are being conducted to see whether other genes are active during lysogeny, examples of which include phage-encoded tRNA and virulence genes.
Alternatively, lysogen can refer to a strain of bacterium that carries a prophage
Prophage
A prophage is a phage genome inserted and integrated into the circular bacterial DNA chromosome. A prophage, also known as a temperate phage, is any virus in the lysogenic cycle; it is integrated into the host chromosome or exists as an extrachromosomal plasmid. Technically, a virus may be called...
.