Viruses



Viruses are tiny, non-living biological infectious agents. So while they aren’t technically alive, they are biological agents and they are infectious. They infect healthy cells. They are going to consist of either a DNA or RNA genome encased in a protein coat known as a capsid. So this capsid is protecting the viral genome until it can get where it wants to go to infect the host cell. And it can only reproduce – these viruses – they can only reproduce by taking over a living host cell. So while they are non-living they must take over a living host cell to be able to reproduce their viral DNA or RNA. Now, once they’re inside a host cell, the virus may remain dormant for awhile so it doesn’t always immediately enter the living host cell and attack. Sometimes it remains dormant for awhile but eventually it is simulated into the active or lytic phase and the virus inserts its on genetic material into that of the host. So the host cell is unware of this the DNA that is or RNA that is mixed in with the host DNA or RNA – it just doesn’t recognize that right away. So the virus is able to take control of the host DNA by mixing with it and then taking over it. It causes the host cell to produce many viral genes and proteins so once it gets in there it starts saying “reproduce, reproduce.” “Make more genes and proteins.” The ones they are making – the ones these cells are making are going to be new viral proteins and genes instead of the normal cells genes and proteins. And then all these viral genes and proteins combine to form new varions or virus particles that destroy the host cell and are released to infect other cells. So what happens is once the virus becomes active and is in the lytic phase, it’s going to insert its own genetic material into that of the host cell – so probably into the nucleus. The virus DNA or RNA is going to mix with the host DNA or RNA, take control of it and then tell it to produce lots more of these viral genes and proteins which combine to form new virions and more and more are being made so fast that the cell can’t keep up and the cell is going to burst or lyce. That’s where we get the lytic cycle or lytic phase from because it is whenever the end result is when the cell is going to be lycing or bursting open and once it bursts open all these varions are released to infect other cells and go and repeat the process. Something to remember is that the genome of both DNA and RNA viruses can be either single or double stranded. A lot of times a virus is going to not be too complex the genome is only going to be three to a hundred genes. It’s not going to be very big but it can be double stranded if it is a more complex virus. So viruses are sneaking little things. they are going to be protected by their protein coat – the capsid and insert their genome – their genetic material into a host cell, take over, reproduce more virual genes and proteins which form so many new varions that it causes these cells to burst open and send out more viruses into the host to attack other cells.

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Provided by: Mometrix Test Preparation

Last updated: 07/25/2017
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