Virus must have a host cell in which to live and make more viruses.
If you have read How Cells Work, you know how both bacteria cells and the cells in your body work. A cell is a stand-alone living entity able to eat, grow and reproduce. Viruses are nothing like that. If you could look at a virus, you would see that a virus is a tiny particle. Virus particles are about one-millionth of an inch (17 to 300 nanometers) long. Viruses are about a thousand times smaller than bacteria, and bacteria are much smaller than most human cells. 1 Capsid: a protective shell around the genome of a virus. 2  Cell membrane: the outside layer of a cell that separates it from its environment. 3  Envelope: part of a cell membrane that is stolen to become the outer layer of some viruses. 4  Genome: all of the genetic information of an organism (living thing)... So, a virus must have a host cell (bacteria, plant or animal) in which to live and make more viruses. Outside of a host cell, viruses cannot function. For this reason, viruses tread the fine line that separates living things from nonliving things. A virus particle, or virion, consists of the following: 1  Nucleic acid-set of genetic instructions, either DNA or RNA, either single-stranded or double-stranded (see How Cells Work for details on DNA and RNA). 2  Coat of protein-surrounds the DNA or RNA to protect it. You cannot grow a virus in a petri dish. The reason is that viruses are considered to be non-living. They do not possess active reproduction machinery on their own. Viruses instead hijack a host cell's machinery, injecting its own DNA or RNA, allowing the host cell to reproduce the virus. 4. Many fungi can grow in acidic conditions which can inhibit growth of competing bacteria. 5. Some species have to have living hosts to grow such as ringworms, yeasts, and athlete's foot fungi or parasites of plants such as rusts, smuts, blights. A virus is a non-cellular particle that consists minimally of protein or nucleic acid (DNA or RNA). Except for a few cases, viruses are not surrounded by a membrane. In order to survive, it must replicate inside another cell, such as a bacterium or a plant and animal cell.
http://science.howstuffworks.com/life/cellular-microscopic/virus-human1.htm https://askabiologist.asu.edu/virus http://science.howstuffworks.com/life/cellular-microscopic/virus-human1.htm http://science.howstuffworks.com/life/cellular-microscopic/virus-human1.htm https://in.answers.yahoo.com/question/index?qid=20090726144458AAlkzg5 https://uk.answers.yahoo.com/question/index?qid=20110107130837AAAr4jP http://www.sproutnet.com/Viruses
what conditions do viruses need to grow