Difference between Viruses and Bacteria | ScienceMonk

Most of us often get confused when asked to differentiate bacteria and viruses. Have you ever thought what makes them different? Well, though bacteria and viruses stand to be microscopic with a lot of similarities among them, there exist certain features which make them two different entities. The location they are found, their size and shape, reproduction method, types of diseases caused, treatment methods and more are some of the few things which set them apart.

This article highlights the differences between these two microscopic organisms to provide a better understanding of the microbial world.

Difference between Viruses and Bacteria

Difference In The habitat of Viruses and Bacteria 

Bacteria, a sporadically growing microorganism and can be found almost anywhere. They grow on other organisms, within an organism as well as on certain inorganic materials. They do not limit themselves to this and can even survive in extremely harsh condition like hydro-thermal vents.

Bacteria surviving in such extreme conditions are also known as extremophiles. Bacteria are capable of infecting almost all eukaryotic organisms like animals, fungi, and plants.

Fact: Do you know even the human body has a lot of bacteria, onto the surface and within the tissues. Example: E.coli is a very common bacteria found in the human intestines. Another example is S.aureus found commonly on your skin.

Viruses, like bacteria, have multiple habitats. They are known as an obligate parasite that is capable of infecting both eukaryotes and prokaryotes such as animals, fungi, plants, archaeans, bacteria and more.

Difference between Viruses and Bacteria

You must have gone through a common question of whether viruses are alive or not? Well, the answer to this is viruses are an obligate parasite, which means they are considered living only when they are into a host system. Otherwise, when present outside the host system in an inactive form, viruses are considered non-living. Viruses can survive on a range of harsh conditions like bacteria and are commonly found in sulphuric waters, thermogenic vents, and more such places.

Defining the Biological Structure of Viruses and Bacteria

Bacteria are a prokaryotic organism that showcases features similar to all other living organisms.

A bacterial cell consists of ribosomes, nuclear material, plasmid, membrane-bound vacuoles immersed in the cytoplasm or protoplasm, which is guarded by peptidoglycan rich cell wall. In some cases, you can also observe pili and flagella like structures which play a crucial role in the movement of bacterial cells.

Viruses, unlike bacteria, are not considered as cells because they are present in the environment as encapsulated particles of nucleic acids, i.e. DNA or RNA.

Mostly the encapsulated membrane is made of protein, but in some cases, viruses have an additional layer of the membrane, also known as envelope rich in phospholipids and proteins. This membrane helps viruses to enter the host system by the method of fusion or direct entry. The viruses without envelope enter the host through the process of endocytosis and exit either by exocytosis or cellular lyses.

Exploring The Size and Shape of Viruses and Bacteria

Bacteria come in varied sizes and shapes. Some come in a spherical shape (cocci), spiral, rod-like (bacilli), vibrio, and more. If you consider the size of a normal bacteria, then it ranges between 200-1000 nm (nanometers). Normally bacteria are not visible by naked eyes, but the world’s largest bacteria, known by the name Thiomargarita namibiensis has a size of 0.75 mm approximately.

Just like bacteria, viruses also come in varied shapes and sizes. However, the structure of the virus depends mainly upon the biological material it carries, i.e. the amount of DNA/RNA or proteins. You can find viruses in spherical shapes (polyhedral), helical, or rod-like shaped capsids.

One of the best examples of viruses is a bacteriophage, it comes with a unique shape wherein it contains a diamond-shaped head, collar, tubular neck, and tail fibers for movement. In comparison to bacteria, viruses are too small and generally seen in sizes range of 20-400nm. Till now the largest virus known is Pandoravirus which comes in a size range of 1000nm or more.

The image shows a bacteriophage with a diamond-like head, tubular neck, and fiber tails.


Mechanism Of Reproduction Of Viruses and Bacteria

There exists various mechanism of reproduction used by microorganisms to expand their population or survive in harsh conditions. Bacteria generally are known to perform asexual mode or reproduction such as through binary fission. During this process, a single bacterial cell replicates its nuclear material and divides it into subsequent daughter cells.

On the other hand, viruses replicate and reproduce with the help of host machinery, it has infected. It is very clear from the fact that viruses lack proper organelles, which can help it to reproduce. Therefore, the virus hijacks the host system and uses its cellular component to replicate its genetic material and reproduce subsequently.

For this, the replicated nuclear material is injected into the cell, wherein instructions are given for synthesis of other viral components. Once available, all the components are assembled to form a mature virus which then breaks the cell and moves out to infect the others or continue the same process further. 

Way Ahead

So, if you ever wanted to understand the difference between a viral infection or a bacterial infection, do look at these points. Infections like the common cold, HIV, zika, ebola, chickenpox, and more are caused by the virus. Whereas, bacteria cause infections like typhoid, pneumonia, tuberculosis, meningitis, and more.

Both viral and bacterial infection requires antibiotic based treatments. However, the intensity of dosage varies depending upon the time and type of infection. We hope this article puts your cognizance over a brief understanding of bacteria and viruses in the world of microbes.

By- Swati Shri Pal Singh

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