Bacteria vs Virus

Typical Gram Positive Bacterial Cell

Difference between Bacteria and Virus

Microbial world consists of all sorts of microscopic and sub microscopic organisms of which bacteria and viruses make up a major part. We have some good bacteria and some bad bacteria. But all viruses cause infections of various types in humans, animals and plants. Bacteria and viruses are poles apart in their morphology and function. Let us understand what separates these two major groups of microbial organisms.

Bacteria

Bacteria are unicellular organisms with a cell wall. It is a prokaryote cell as it does not contain membrane bound organelles. It does not have a nucleus. The bacterial membrane is made up of a cell wall and cell membrane. The cell wall is made up of peptidoglycan or lipopolysaccharide. It contains free floating DNA and RNA which is responsible for cell division and multiplication. The bacteria divide by binary fission.

Bacteria are found all over the planet and can be divided into healthy and harmful variety. Healthy bacteria present in the human gut aids digestion and produces important vitamins. The bacteria can grow on non-living surfaces. They move with the help of membranous extensions called cilia or flagella. It can also temporary extension called pseudopods to move ahead.

Bacteria come in various shapes and sizes. They can be spherical, rod shaped or even spiral. They can extend up to few micrometres (1000nm) in length. Bacterial infections are usually localised and are treated by antibiotics.

Common bacterial infections include cholera, typhoid, tuberculosis, syphilis etc.

Virus

Structure of the influenza virion.

These are the smallest infectious microbial organisms (20-400 nm) present on this earth. Scientists have yet to categorise them into living or non-living. They are around 10-100 times smaller than the bacteria. The viruses do not contain any cell wall and is contained by a protein coat.

It contains genetic material which may be DNA and RNA and some protein molecule but does not have the ability to multiply by itself. The virus multiplies by attaching itself to the host DNA and in the process destroys the host cell completely. It requires a host cell to grow and multiply.

Almost all viruses are harmful and viral infections are extremely difficult to treat. Anti-viral vaccines (polio drops) and anti-viral drugs such as interferon can help to restrict the spread of virus but viruses are very difficult to destroy. Viral infections are systemic and affect the entire body. Viruses can infect all living organisms.

Advent in technology has helped scientists to come up with vaccines made up of viruses to destroy certain types of cancers.

Viral diseases include hepatitis, HIV, HSV, influenza etc.

To summarise bacteria are single celled microorganisms with the ability to grow and multiply outside the host body. On the other hand, viruses can only grow when inside the cell body of an organism. It uses the host DNA to replicate and in the process take over the host cell completely.