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VIRUS

    A virus is a microscopic parasite that can infect living organisms and cause disease. It can make copies of itself inside another organism's cells. Viruses consist of nucleic acid and a protein coat. Viruses are able to cause many types of diseases such as polio, ebola and hepatitis.
    Viruses reproduce by getting their nucleic acid strand into a prokaryote or eukaryote (cell). The RNA or DNA strand then takes over the cell machinery to reproduce copies of itself and the protein coat. The cell then bursts open, spreading the newly created viruses. All viruses reproduce this way, and there are no free-living viruses. Viruses are so much smaller than bacteria. They were no visible until the invention of the electron microscope.
     Viruses are everywhere in the environment, and all organisms can be infected by them.  Viruses can remain intact for a long time, and will infect cells when the time and conditions are right. Certain viruses are transmitted through close contact between people. So, avoid viruses transmission by using face mask and doing physical distancing.  

 Why does  virus need host?