Virus vs Bacteria

Viruses and bacteria are microscopic organisms. They may not be visible by naked eyes, but millions of them surround us all.

Viruses are an assembly of different molecules containing genetic material. Most biologists do not consider them living, as they need to enter a host cell to survive and reproduce. However, they are also quite selective about their hosts.

Bacteria are the smallest and simplest microbes with a free-floating genetic material. They are abundant in soil, inhabiting plant root systems to help them in nitrogen-fixation. Also, within the human body, they inhabit the digestive system to aid in energy metabolism and digestion.

Compare and Contrast

Though both of them are microbes and cause serious harm to the living world, they are pretty different in their structure, composition, and mode of action. So let us discuss their differences.

What Is the Difference between Virus and Bacteria

Basis	Virus	Bacteria
1. Living or Nonliving	Non-living, can only replicate within a host cell.	Living organism, can replicate independently or inside a host cell.
2. Cell Type	Do not qualify as cells. So, they are neither prokaryotic nor eukaryotic.	Consist of a single prokaryotic cell.
3. Structure	Composed of a protein coat (capsid) that contains the genetic material (nucleic acid).	Composed of cell organelles. DNA immersed within the cytoplasm and surrounded by a cell wall.
4. Size	Smaller than bacteria. Typically range in size between 20 to 400 nm in diameter.	Larger than viruses. Typically range in size between 200 to 1000 nm in diameter.
5. Shape	Can be polyhedral, spherical, or helical.	Can be spherical (cocci), rod-shaped (bacilli), comma-shaped (vibrio), or spiral.
6. Cells They Infect	Can infect both plant and animal cells (plant virus and animal virus). They can even infect a bacterial cell (bacteriophage or phage virus).	Can infect both plant and animal cells.
7. Visibility Under Microscope	Visible under the electron microscope.	Visible under the light microscope.
8. Reproduction	Insert their genetic material into the host genome and produce multiple copies.	Undergo asexual reproduction by binary fission. They can also reproduce by exchanging their genetic material by conjugation.
9. Host Dependence	Host-dependent	Host-independent
10. Genome & Nucleic Acid	Have either DNA or RNA as their genetic material.	Have a free-floating single chromosome of the circular double-stranded DNA helix (plasmid). The area of the cell that contains the DNA is called the nucleoid.
11. Replication	Replicate within the host cell by hijacking its cellular machinery.	Replicate through binary fission.
12. Cell Organelles	Lack a nucleus, ribosomes, or any other cell organelles. Instead, it only contains a membrane known as an envelope, made of phospholipids.	Cell organelles, such as cell walls, ribosomes, and cell membranes, are present in bacteria, except the nucleus.
13. Outer wall	Do not contain a cell wall. Instead, the genetic material is encased by a protein coat (known as a capsid) or a fat layer.	The cell wall is made of peptidoglycan and sometimes lipopolysaccharides.
14. Type of Infections Caused	Generally systemic infections, i.e., affecting the entire body, rather than a single organ or body part. For example, measles, influenza, and flu.	Generally localized infection, i.e., an infection that is limited to a specific part of the body and has local symptoms. For example, pneumonia, tuberculosis, food-poisoning.
15. Common Diseases Caused	Measles, rubella, chickenpox/shingles, roseola, smallpox, chikungunya, and mumps.	Cholera, leprosy, tuberculosis, plague, syphilis, anthrax.
16. Treatment	Not cured by antibiotics. Antiviral drugs block some but not all viruses from entering the body or stop them from reproducing.	Cured by antibiotics.
17. Examples	Coronavirus, Human immunodeficiency virus (HIV), Influenza virus, Herpes virus, Human papillomavirus (HPV).	Escherichia coli, Salmonella Typhi, Vibrio cholera, Streptococcus pneumonia, and Lactobacillus acidophilus.

What Do Viruses and Bacteria Have in Common

Although vastly different from each other, both bacteria and viruses share some common features. They are given below:

No membrane-bound organelles.
Microscopic
Causes disease
Carry genetic material
Can spread through coughing, sneezing, or coming into contact with contaminated surfaces, animals, items, or people.
Can be treated with vaccines

References
- 1. 28 Differences between Bacteria and Virus – Microbenotes.com
  2. Differences between Bacteria and Viruses – Thoughtco.com
  3. Virus Vs Bacteria – Microscopemaster.com
  4. What’s the Difference between Bacteria and Viruses? – Imb.uq.edu.au
  5. Bacterial and Viral Infections – Webmd.com