Lytic cycle
The lytic cycle is one of the two cycles of viral reproduction, the other being the lysogenic cycle. These cycles should not, however, be seen as discrete and separate, but rather as somewhat interchangeable. The lytic cycle is typically thought of as the main method of viral replication, since it results in the destruction of the infected cell, which is how viruses cause damage to their hostss.
Description
The lytic cycle is a three-stage process.
Infection
When a virus infects a cell, it first binds with the cell membrane using receptor molecules on the virus's surface. The virus then injects its genetic material, which can be either DNA or RNA, into the cell.
Growth
The viral nucleic acid takes over and uses the host cell’s organelles to make many copies of the virus. In the case of DNA viruses, the DNA transcribes itself into messenger RNA (mRNA) molecules that are then used to direct the ribosome. In retroviruses, or RNA viruses, a unique enzyme called reverse transcriptase transcribes the viral RNA into DNA, which is then transcribed again into mRNA.
Replication and lysis
After many virus copies are made, they are assembled into complete viruses. The cell eventually becomes filled with viruses (typically 100-200) until it bursts, or lyses; this end process gives the cycle its name. The new viruses are free to infect other cells.
|
|
