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The "early", "middle" (DNA replication), and "late" genes (virus structure), roughly represent the time course of gene expression. [74] Bacteriophage genomes can be highly mosaic, i.e. the genome of many phage species appear to be composed of numerous individual modules. These modules may be found in other phage species in different arrangements.
During fd phage assembly, the phage DNA is first packaged into a linear intracellular nucleoprotein complex with many copies of the phage gene 5 replication/assembly protein. The gene 5 protein is then displaced by the gene 8 coat protein as the nascent phage is extruded across the bacterial plasma membrane without killing the bacterial host.
A prophage is a bacteriophage (often shortened to "phage") genome that is integrated into the circular bacterial chromosome or exists as an extrachromosomal plasmid within the bacterial cell. [1] Integration of prophages into the bacterial host is the characteristic step of the lysogenic cycle of temperate phages.
In contrast, during electroporation the lipid molecules are not chemically altered but simply shift position, opening up a pore which acts as the conductive pathway through the bilayer as it is filled with water. Electroporation is a dynamic phenomenon that depends on the local transmembrane voltage at each point on the cell membrane.
Electroporation – use of an electrical field to increase cell membrane permeability. Phage therapy – therapeutic use of bacteriophages. Transfection – means of inserting DNA into a cell. Transformation (genetics) – means of inserting DNA into a cell. Viral vector – commonly used tool to deliver genetic material into cells.
3. The phage DNA then moves through the cell to the host's DNA. 4. The phage DNA integrates itself into the host cell's DNA, creating prophage. 5. The prophage then remains dormant until the host cell divides. 6. After the host cell has divided, the phage DNA in the daughter cells activate, and the phage DNA begins to express itself.
Lambda phage is a non-contractile tailed phage, meaning during an infection event it cannot 'force' its DNA through a bacterial cell membrane. It must instead use an existing pathway to invade the host cell, having evolved the tip of its tail to interact with a specific pore to allow entry of its DNA to the hosts.
The phage first adheres to the cell surface with its tail parallel to or leaning at an angle to the cell surface in the pre-infection stage. The tail then firmly stands on the cell surface and extends its fibers horizontally, rendering the phage infection-competent, after which viral DNA is released into the cell through an extensible tube. [21]