Difference Between Virus And Bacteria

We have learned about different types of microbes, with their structure, habitat, different ways they are beneficial to humans and also about the various diseases and infections caused by these microbes. Both bacteria and viruses cause mild to serious infections, but they are different from each other. Therefore, before learning about the infectious disease caused by these microbes, it is more important to understand the morphology, anatomy, and differences between bacteria and viruses.

What is Bacteria?


Bacteria are microscopic and single-celled entities that flourish in diverse surroundings.  They can be found thriving in the soil, human gut, in the aquatic habitat, etc. These tiny bacteria are useful to mankind while others may be unpleasant and cause diseases. The bacteria that cause infectious diseases are known as pathogens.

They are classified into prokaryotes that are single-celled entities with a basic internal structure that has no nucleus and possesses DNA which either moves freely in a structure resembling a twisted, thread-like mass known as the nucleoid or in distinct circular fragments called as fragments. The bacterial cell contains the ribosomes that are spherical units in which proteins assemble from amino acids with the use of data that is encoded in the ribosomal DNA.

Importance of Bacteria: Bacteria have had a profound impact on the world’s ecology, and play a major role in modern medicine and agriculture.

Characteristics Of Bacteria

  • Bacteria are single-celled entities. Most of them(eubacteria and archaeans) grow as independent single cells while some bacteria(myxobacteria) living in the soil form multicellular fruiting bodies that are part of their life cycle.
  • Bacteria do not possess complex organelles inside the cells. They do possess an internal organization since the DNA is segregated into sites known as a nucleoid, but these nucleoids are not actually divided from the remaining cell through a membrane
  • The plasma membrane is not a feature of bacteria as seen in other living cells. Specialized folding of the plasma membrane enables the photosynthetic bacteria to carry out light-dependant reactions of photosynthesis which the photosynthetic eukaryotes carry out on the thylakoid membranes inside the chloroplast

Also, refer Bacteria 

What is a Virus?


Viruses are tiny, microscopic parasites which contain either RNA genome or DNA, in some cases with associated enzymes and are smaller compared to bacteria. They lack the potential to thrive. It is girdled by a protein coat that is enclosed by a membrane made of carbohydrates and protein. The membrane can be composed of the membranes of the infected cells.

Characteristics Of Virus

  • Viruses reproduce at a tremendous pace but inside the cells of the living hosts only and have the capability to mutate
  • These microbes  lack cell and other cellular organelles or cytoplasm
  • Most of the viruses contain RNA or DNA, and not both.
  • They fail to perform metabolic activities. They make use of the metabolic machinery of the host cells. Viruses cannot grow and divide. They produce and assemble new viral components inside the infected host cell

Also, refer Virus

Differences Between Virus And Bacteria

Here is a difference between the and they are mainly differentiated based on their different characteristics and other features.

Cell Wall Lipopolysaccharide or Peptidoglycan Protein coat is present instead. No cell wall.
Size Larger. Ranges between 900 – 1000nm Smaller. Ranges between 30-50nm
Number of cells It is Unicellular It has no cells
Non-Living/Living It is a living organism It is between living and non-living things
Mode of Reproduction Asexual reproduction – Fission It attacks host cell takes over the cell prompting it to make copies of the viral RNA/DNA.
Ability to Reproduce Able to reproduce by itself Need a living cell to reproduce
Ribosomes Are Present Are Absent
RNA and DNA RNA and DNA drifting freely in the cytoplasm RNA and DNA enveloped inside a protein coat.
Infections Localized Systemic
Incubation period 9-10 days 6 to 6 days.
Diseases/Infections Gastritis, Food poisoning, ulcers, meningitis, and pneumonia, etc. AIDS, common cold, influenza, chickenpox, etc.
Treatment Antibiotics Antiviral drugs
Examples Vibrio cholerae, Staphylococcus aureus, etc. Hepatitis A virus, HIV, Rhino Virus, etc.

Important Questions for you

Q.1. Why are viruses not affected by antibiotics?

A.1. The property of antibiotics is to target proteins/structures present in the bacteria that are not found in viruses. The usual targets of the bacteria are the cell wall, metabolic pathways, DNA gyrase, ribosomes or topoisomerase. This is the same reason why antibiotics have no effect on human targets. It operates on the basis of selective toxicity as in the antibiotics target primarily the bacteria.

Q.2. Why are viruses known as obligate parasites? 

A.2. Virus particles are inert outside cells. It is because they lack the metabolic machinery of their own to produce energy or for protein synthesis hence they are dependant on host cells for vital functions.

Q.3. List five diseases caused by viruses.

A.3. Smallpox, Ebola, Hepatitis, Herpes, and cold sores, HIV/AIDS

Q.4. Write any five applications of bacteria.

A.4.  Bacteria is extensively used in the fermentation process such as baking, brewing, etc

The Lactobacillus bacteria are known to form curd from milk

Bacteria are used in the chemical manufacturing of ethanol, organic acids, enzymes, etc

They are used in the production of pharmaceuticals

Bacteria finds its applications in the process of nitrogen fixation also, which is crucial in maintaining the nitrogen levels in the atmosphere and also for plant growth

Q.5. Which bacteria are resistant to antibiotics?

A.5. Usually, bacteria do not resist antibiotics, but some bacteria such as the golden staph or the Staphylococcus and the Neisseria gonorrhoeae have developed a resistance to the antibiotic, benzylpenicillin.

Learn more about the differences between virus and bacteria, and other related topics @ BYJU’S Biology

Practise This Question

Assertion: Floatation is an efficient technique to separate cells during downstream processing.
Reason: Bubbling of air through fermentation mix makes the biomass float on the surface along with foam.