A virus contains nucleic acid and a capsid. The nucleic acid can be DNA or RNA and they both can be single or double stranded. The capsid is a protein coat. Some viruses also contain an envelope, or a lipid bilayer. These components create a bacteriophage, which is the vessel that viruses spread.Viruses reproduce using the cell that they are connected to. This occurs through the lytic and the lysogenic cycles. The lytic cycle begins with a bacteriophage attaching and piercing through a cell. then, it injects its DNA into the cell. As the cell goes through transcription and translation, the virus DNA tags along. Bacteriophages are assembled inside the cell, and then they lyse or burst out of the cell to attach to more cells. The other cycle is the lysogenic cycle. this reproductive method starts the same way, with the virus attaching to a cell and injecting its DNA. The virus DNA actually inserts itself into the chromosomes of that cell, where it hides out. The cell will replicate like normal, with the virus DNA hiding the whole time. The cells can enter both cycles, and so eventually cells in the lysogenic cycles enter the lytic cycle, resulting in a viral takeover.This year, the flu seems to be an emerging viral threat. People are advised to receive their flu shot and to practice good hygiene habits. There are four different variations of the flu (2 versions of Influenza A and 2 of Influenza B) so its best to be on the safe side this flu season and to get a flu shot. Even if its not helpful, at least you can say you got one. A severe influenza outbreak occurred in 1918, where a strain of H1N1 killed healthy adults. This was a devastating attack, considering that this happened in the same time period as the first world war. These adults were diagnosed with the flu if they had any of the symptoms: fever, cough, sore throat, chills, body aches, etc.. This was an outbreak of epic proportions.There are three theories as to how viruses came to be. One is the cellular theory, which states that maybe viruses were a part of cells and this is where they evolved from. Another is the regressive theory, which states that viruses might have once been cells. The viruses then regressed into a state where they needed to depend upon another cell in order to survive. The third theory deals with coevolution, and it states that perhaps cells and viruses evolved side by side. While the origin of them is not clear, there are several theories as to how they came to be.A common misconception that some people might have is that since viruses can spread and do all of these things that they are alive. This is inaccurate, as viruses are parasitic. they are not alive, and as a result they don’t have a metabolism. They rely completely on the cell that they are attached to in order to survive.