Figure 13.2, Purves's Life: The Science of Biology, 7th Edition
Lytic Cycle vs. Lysogenic Cycle
Lytic cycle
Kills the host bacterium.
Virulent virus: a virus that only reproduces using the lytic cycle
Lysogenic cycle:
Does not kill the host bacterium.
Viral DNA becomes incorporated into the host DNA.
Once it is integrated it is called a prophage.
The prophage will remain silent and be faithfully reproduced with the host DNA until some point it exits the bacterial chromosome and goes through the lytic cycle.
Temperate virus: a virus that uses both modes of reproduction
RNA as Genetic Material
Retroviruses (e.g. HIV) use RNA to make DNA, hence the name—“retro.”
An important enzyme called reverse transcriptase allows them to do this.
It transcribes DNA from an RNA template.
This is a violation of the standard pathway of information flow (DNA → RNA → protein), and hence a modification, some would say, violation, of the central dogma.
Modified figure 12.2, Purves's Life: The Science of Biology, 7th Edition