Comparison Table: Virus and Bacteria – Structure, Reproduction & More
There are different types of Microbes in our surroundings and some of these Microbes are useful to humans, whereas some of them cause various harmful diseases. Apart from this, Bacteria and Viruses cause the majority of diseases. They lie between mild to severe disease. Bacteria are tiny, single Celled organisms that get their food from the environment and their surrounding. Some Bacterias are good for the human body, for Example Lactobacillus as they help in our digestive activities and keep harmful Bacterias outside from the body. Whereas Viruses are even more smaller than Bacteria and they exist in both living and nonliving form. Outside the host body they are in nonliving form whereas when they are inside the host body they are a living organism and utilize the host Cell process.
Virus versus Bacteria
What is Bacteria?
Bacteria are microscopic single- Celled organisms, they can live in soil, the ocean, inside the human gut. Humans have a very complex relationship with Bacteria as they help them in various ways, such as by curdling milk into yogurt or helping with our digestion.
Structure of Bacteria
Bacteria are single-Celled organisms who lack nucleus, and contain DNA that either floats freely in twisted form or in thread-like structure known as nucleoid. In Bacteria ribosomes are spherical units where proteins are assembled from individual amino acids using information encoded in ribosomal RNA.
Bacteria are covered by an outer Cell wall and an inner Cell membrane but certain Bacteria do not have Cell walls like mycoplasma and some Bacteria may have a third layer also known as a capsule. Flagella is also present on the surface of Bacteria.
Classification of Bacteria
Bacteria are classified on the basis of below features:
Shape
Composition of the Cell wall
Mode of respiration
Mode of nutrition
1.Classification based on shape:
Bacillus (rod shaped)
Spirilla or spirochete (Spiral)
Spirilla or spirochete (Spiral)
Vibrio (Comma-shaped)
2.On the Basis of Composition of Cell Wall:
Peptidoglycan Cell wall: Gram positive Bacteria
Lipopolysaccharide Cell wall: Gram negative Bacteria
3.Bacteria on the Basis of Nutrition:
Autotrophic Bacteria
Heterotrophic Bacteria
4.On the Basis of Mode of Respiration:
Aerobic Bacteria: Lipopolysaccharide Cell wall
Anaerobic Bacteria: Mycobacterium
Properties of Bacteria
Mainly there are three properties of Bacteria they are:
They are uniCellular
They lack membrane bound organelles
Usually microscopic in size
Infection Caused Bacteria
An infection occurs when another organism enters our body and causes disease inside our body. The organisms that cause infections are very diverse and can include things like Viruses, Bacteria, fungi, and parasites.
Infection Caused by Bacterias are:
Sore throat
Urinary tract infection(UTIs), caused by coliform Bacteria
Food poisoning
Gonorrhea
Syphilis
Chlamydia
Tuberculosis
Whooping cough
Lyme disease
Meningitis
Cholera
What is Virus?
Viruses are microscopic parasitic organisms usually smaller than Bacteria and having a tendency to reproduce inside the host Cell only. They cause so many diseases and death all over the world. They are made up of core genetic material either DNA or RNA and surrounded by a protective coat called capsid which is made up of protein.
Structure of Virus
They are small intraCellular parasites which contain either DNA or RNA surrounded by a protective protein coat known as capsid. For propagation Viruses mainly depend on their host body. A complete Virus particle known as virion. Main function of virion is to deliver its DNA or RNA to the host Cell so that the genome can be translated or transcripted into the host body.
Classification of Virus
Viruses are classified on the basis of:
Structure
Shape
Type of host
1.On the Basis of Structure
Cubical Virus: they are also known to have icosahedral symmetry Virus. Eg: ReoVirus, PicornaVirus
Spiral Virus: they are known as helical symmetry Virus.
Eg: OrthomyxoVirus
Radial symmetry Virus: Eg: bacteriophage
Complex Virus: Eg: pox Virus
2.On the Basis of Shape
Rabies Virus: Bullet shaped
Ebola Virus: Filamentous shaped
PoxVirus: Brick shaped
3.On the Basis of Host Body
Animal Virus: The Viruses which infect and live inside the animal body including man are called animal Viruses. Eg; influenza Virus, rabies Virus, mumps Virus, polioVirus etc. Their genetic material is RNA or DNA.
Plant Virus: Virus which lives inside the plant body is known as plant Virus. Eg: The tobacco mosaic Virus, potato Virus, beet yellow Virus and turnip yellow Virus etc.
Bacteriophage: It is a kind of Virus which infect Bacterial Cells known as bacteriophage.
Infection Caused by Virus
Influenza.
Japanese encephalitis (inflammation of the brain)
Measles, mumps, and rubella.
Polio
Rabies
Vedantu has enough material on Viruses and Bacteria. Students can read from Difference Between Virus and Bacteria and then understand better. This page can be referred to by all students of Biology to know more about the topic. This material can also be downloaded in the form of a PDF and then be read.
FAQs on Virus vs Bacteria: What Sets Them Apart?
1. What is the main difference between a virus and a bacterium?
The main difference is that bacteria are living, single-celled organisms with their own cellular machinery to reproduce, while viruses are non-living particles that are much smaller and require a host cell to replicate. Bacteria can survive independently, whereas viruses are obligate intracellular parasites.
2. How does the structure of a bacterium compare to a virus?
A bacterium has a complex cell structure with a cell wall made of peptidoglycan, a cell membrane, cytoplasm, and genetic material (DNA) in a nucleoid region. In contrast, a virus is much simpler, consisting only of genetic material (either DNA or RNA) enclosed within a protein coat called a capsid. Viruses lack a true cellular structure.
3. What are the key differences between viruses and bacteria in point format?
Here are the key differences between viruses and bacteria:
- Living Nature: Bacteria are living cells, while viruses are non-living entities on the border of living and non-living.
- Size: Bacteria are microscopic (approx. 1000 nm), but viruses are ultramicroscopic and significantly smaller (approx. 20-400 nm).
- Reproduction: Bacteria reproduce independently through binary fission. Viruses must invade a host cell and use its machinery to replicate.
- Treatment: Bacterial infections can be treated with antibiotics. Viral infections do not respond to antibiotics and are managed with antiviral drugs.
- Structure: Bacteria are prokaryotic cells with organelles. Viruses are acellular, with no cytoplasm or organelles.
4. For a Class 8 student, what is the most important difference between a virus and a bacterium?
For a Class 8 student, the most important difference to remember is how they are treated. Antibiotics can kill bacteria and cure bacterial diseases like typhoid, but they have no effect on viruses that cause illnesses like the common cold, flu, or COVID-19. This is a crucial concept in understanding basic health and medicine.
5. How do viral infections and bacterial infections differ?
Bacterial infections are caused by the proliferation of harmful bacteria inside the body, often localized to a specific area (e.g., strep throat) or systemic. They are typically treated with antibiotics. Viral infections occur when a virus enters host cells and uses them to replicate, often affecting the entire body. Treatment involves antiviral medications that inhibit the virus's replication cycle, and often focuses on managing symptoms while the immune system fights the infection.
6. Why is a virus considered to be on the border between living and non-living?
A virus is considered on the border of living and non-living because it exhibits characteristics of both. Like living organisms, it contains genetic material (DNA or RNA) and can evolve. However, like non-living things, it is inert outside a host cell, cannot carry out metabolic processes, and crystallises. It only becomes active and replicates once it has infected a living cell.
7. Are all bacteria harmful to humans?
No, not all bacteria are harmful. In fact, the vast majority are harmless or even beneficial. For example, bacteria like Lactobacillus help in digesting food in our intestines and are used to make curd and cheese. Harmful bacteria that cause diseases are called pathogenic bacteria, but they represent only a small fraction of all bacterial species.
8. Can a virus reproduce on its own like a bacterium?
No, a virus cannot reproduce on its own. It lacks the ribosomes and enzymes necessary for replication. A virus must attach to a specific host cell, inject its genetic material, and hijack the host's cellular machinery to produce new virus particles. This process is called replication, not reproduction, and it ultimately destroys the host cell. Bacteria, being true living cells, reproduce independently via binary fission.
9. What are some examples of diseases caused by viruses and bacteria?
It is important to know which microbe causes a disease for proper treatment. Here are some common examples:
- Bacterial Diseases: Tuberculosis, Typhoid, Cholera, Tetanus, and Strep Throat.
- Viral Diseases: Common Cold, Influenza (Flu), Measles, Polio, and COVID-19.
