Virus biology
The function of a capsid, in virus biology, is to serve as a protective outer layer that protects the genetic material of the virus from the host’s defensive cells. The capsid is made up of proteins. The nucleic acid is what is contained within the capsid, which is a group of long, linear macromolecules, consisting of either DNA or RNA. There are two different cycles in which the virus uses a host cell to replicate and reproduce itself. These two cycles are known as the lytic cycle, and the lysogenic cycle. In the lytic cycle, viral particles are made from the host bacteria cell’s DNA, and replicas of the virus are made and sent back into the environment. The steps that make up this cycle are: the virus latches to the bacteria cell, which then inserts its DNA into the bacteria, effectively taking over the cell’s machinery. It then reproduces itself and self-assembles. The replica viruses then burst from the host cell, destroying the host. In the second cycle, the lysogenic cycle, the virus begins as a prophage, the latent form of a bacteriophage, and binds to the bacteria. The viral DNA then gets incorporated into the cell’s chromosome, and is replicated along with the host cell’s chromosomal material. The basic differences between the two cycles is that the lytic cycle is exhibited by virulent phages (otherwise known as bacteriophages), where the lysogenic cycle is exhibited by temperate phages, and that lysis, the destruction of the host cell, occurs only in the lytic cycle. One way that we prevent these viruses from taking over our bodies is vaccines. Vaccines, often in the form of a shot, introduce a weakened form of the disease into the body. Given this introduction, the body is then able to create appropriate antibodies to fight the virus; therefore, if the actual disease were to make its way into the body, the antibodies created by means of the vaccine would simply return and rid the body of the virus. Some examples are viruses would be: polio, influenza,