The lytic cycle is one of the two cycles of viral reproduction, the other being the lysogenic cycle. The lytic cycle results in the destruction of the infected cell and its membrane.]citation needed[ A key difference between the lytic and lysogenic phage cycles is that in the lytic phage, the viral DNA exists as a separate molecule within the bacterial cell, and replicates separately from the host bacterial DNA. The location of viral DNA in the lysogenic phage cycle is within the host DNA, therefore in both cases the virus/phage replicates using the host DNA machinery, but in the lytic phage cycle, the phage is a free floating separate molecule to the host DNA.
Clinical pathology (US, UK, Ireland, Commonwealth, Portugal, Brazil, Italy), Laboratory Medicine (Germany, Romania, Poland, Eastern Europe), Clinical analysis (Spain) or Clinical/Medical Biology (France, Belgium, Netherlands, Austria, North and West Africa...), is a medical specialty that is concerned with the diagnosis of disease based on the laboratory analysis of bodily fluids, such as blood, urine, and tissues using the tools of chemistry, microbiology, hematology and molecular pathology. This specialty requires a medical residency and should not be confused with Biomedical science, which is not necessarily related to medicine.
The American Board of Pathology certifies clinical pathologists, and recognizes the following secondary specialties of clinical pathology:
Lysogeny, or the lysogenic cycle, is one of two methods of viral reproduction (the lytic cycle is the other). Lysogeny is characterized by integration of the bacteriophage nucleic acid into the host bacterium's genome or formation of a circular replicon in the bacterium's cytoplasm. The genetic material of the bacteriophage, called a prophage, can be transmitted to daughter cells at each subsequent cell division, and a later event (such as UV radiation or the presence of certain chemicals) can release it, causing proliferation of new phages via the lytic cycle. Lysogenic cycles can also occur in eukaryotes, although the method of DNA incorporation is not fully understood.
The distinction between lysogenic and lytic cycles is that the spread of the viral DNA occurs through the usual prokaryotic reproduction, while the lytic phage is spread through the production of thousands of individual phages capable of surviving and infecting other cells. The key difference between the lytic cycle and the lysogenic cycle is that the lysogenic cycle does not lyse the host cell. Phages that replicate only via the lytic cycle are known as virulent phages while phages that replicate using both lytic and lysogenic cycles are known as temperate phages.
P1 is a temperate bacteriophage (phage) that infects Escherichia coli and a some other bacteria. When undergoing a lysogenic cycle the phage genome exists as a plasmid in the bacterium unlike other phages (e.g. the lambda phage) that integrate into the host DNA. P1 has an icosahedral "head" containing the DNA attached to a contractile tail with six tail fibers.
The P1 phage has gained research interest because it can be used to create the P1-derived artificial chromosome cloning vector which can carry relatively large fragments of DNA. Also, P1 encodes a site-specific recombinase, Cre, that is widely used to carry out cell-specific or time-specific DNA recombination by flanking the target DNA with loxP sites.(see Cre-Lox recombination)