Virus: What it is and how it works

Virus: What it is and how it works

The virus is a biological organism that is not made up of cells, such as bacteria, plants or animals, but it’s built in a peculiar way.

It is made like a chocolate egg with a surprise. Except the surprise is not particularly welcome for those who receive it.



The virus is very small, so much so that it is not possible to see it with the naked eye, but you must use an electron microscope. Its size is far less than that of bacteria, considered until the 19th century the smallest biological entity on earth. If the bacteria was as big as an orange, the virus would be the size of a bread crumb.

Coming into contact with a virus is very simple. The virus is transmitted by either contact or by air, for example by sneezing, and that’s it: the virus can now creep into our body, colonize cells and replicate.

Virus structure

It is possible to imagine the virus as two boxes one inside the other. The smaller box contains the virus’ genetic information, which can be DNA or RNA, and the outer box is made up of proteins and has the function of protecting the genetic material of the virus. In some cases there is a third external box, made up of lipids and glycoproteins: in this case the virus takes the name of “coated”.

In addition, viruses can have different structures, such as proteins with specific functions, called enzymes.


Purpose of the virus

The virus can replicate, and consequently spread, only within another organism. In fact, the virus needs a “host” to replicate its genetic material. He is a kind of hacker who infiltrates the cell, borrows its tools and creates copies of himself. After multiplying, the virus exits the cell and colonizes nearby ones.

How do viruses multiply?

Viruses need a host cell to replicate their genetic material. The cell is the smallest biological unit and inside of it it’s where proteins are produced, DNA is replicated and energy is stored. The structure of the virus is so basic that it does not have the necessary tools to perform the same functions of a cell, that’s why it must infiltrate the unaware host: to use its replication tools and the energy necessary for its reproduction. We can appear the virus to a USB stick which contains all the information necessary for printing, but it must connect to a computer to start the process and to a printer to print new pages.


The virus is intelligent because it manages to inject its genes or to penetrate the cell without being identified by the latter as dangerous for the body. The virus replication process occurs in two ways:

  • Since it is not treated as a stranger by the cell, the virus begins to multiply using the cell’s resources. When all the resources have been used up, the cell membrane breaks. The virus has achieved its purpose (ie to multiply as much as possible within a cell) and is now free to penetrate other cells and start the reproduction process from the beginning.
  • The virus hides in the genetic material of the cell and remains “latent”. The cell does not notice the intrusion and continues its normal life cycle. The virus is like a Trojan horse that enters the cell and goes unnoticed but actually encloses the enemies inside it. When the host cell creates new cells, it replicates both its genetic material and that of the virus. When it decides to become “active” and begin the replication process, the virus is already present in a large number of cells.

This multiplication process is relatively quick and it’s completed within 8 to 24 hours.


Can the virus call itself a living organism?

Viruses were discovered in the 19th century, and since they are able to reproduce (although only within a host cell), it was automatic for scientists of the time to consider them organisms, therefore forms of real life. Over time and with the advent of more complex technologies, scientists noticed that the virus lacked the necessary mechanisms to perform the common functions of a living organism.

Certainly, viruses have characteristics in common with living organisms, since they both have different levels of organization, and in a certain way they are able to reproduce and adapt to the environment. Unlike organisms though, the virus is not made up of cells, it is unable to maintain itself in a stable state, does not grow and does not produce energy.

Since viruses are the most widespread biological entity on Earth, they are able to colonize other living beings, change and adapt to the environment, perhaps the question we should ask ourselves is not whether viruses are living organisms or not, but rather what role they play in the development of life as we perceive it today.

Med4Care Marco De Nardin

Marco De Nardin, MD, Anaesthesiologist and Intensive Care Doctor









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