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Bacteria and Viruses are two types of microorganisms. Microorganisms are very small organisms that cannot be seen with naked eyes. Bacteria and Viruses can be found in soil, water, and the air around us. Bacteria and viruses are also present on our bodies. Bacteria and viruses are very important for us as they cause different problems including unhealthy conditions in our body leading to different diseases like cough, fever, cold, etc. In this article, we will learn more about bacteria and viruses, and understand the difference between the two.
| Table of Content |
Keyword Takeaways: Bacteria, Virus, Prokaryotes, Microorganisms, Cell, Nucleus, Antibiotics
What is Bacteria?
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Bacteria are single-celled microorganisms that have cell walls, but also lack an organized nucleus and other structures. Bacteria are very small organisms that live in almost every habitat on the earth. They perform a very important role in the ecosystem by decomposing waste products and turning them into the soil. There are over 3,000 kinds of bacteria in the human body that can help protect it from diseases.
Bacteria
Read: Microbiology
Characteristics of Bacteria
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The simplest form of life on earth along with plants and viruses, bacteria is a cell with nucleoids surrounded by a single or double membrane.
- The cells are so small that one bacterium can fit in the space between two atoms.
- It lacks organelles such as nucleus and mitochondria and also does not possess any internal cytoplasmic structures.
- The cell has ribosomes which help in making proteins.
- Bacteria are also producers, consumers, decomposers and they exploit a wide range of environmental resources.
- Bacteria are unicellular prokaryotic cells or microorganisms.
- Their distinctive features include a large circular double-stranded DNA molecule, plasmid DNA that can replicate autonomously, relatively simple growth requirements, and reproduction via binary fission.
Read: Difference between Lysosome and Ribosome
Structure of Bacteria
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Bacteria has five main components.
- NUCLEOID (DNA) – The single chromosome which is located in a region cell is known as a nucleoid.
- RIBOSOMES – It is a place where all the proteins are put together.
- CELL MEMBRANE – It acts as a barrier around the cell.
- CELL WALL – It is the outer layer of the cell that protects bacteria.
- CYTOPLASM – It is a fluid inside the cell.
Bacteria Cell Structure
What is a Virus?
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Viruses are the very small infectious agent that is not visible to the eye. They can infect only living organisms and multiply within the cells of the host organism. The budding virus can enter any type of cell and affects its normal functions. The cells get destroyed by viruses. Viruses cause a variety of diseases in human beings, plants, and animals.
Virus
Virus Microorganisms or simply "germs", are only small in size but cause very harmful diseases. If we come in contact with germs, these germs can enter our bodies and cause diseases. Viruses are the tiniest type of microorganisms that can develop only inside the cell of the host organisms. In other words, viruses kill or damage the cells and then insert them by their own genetic material and protein. It is composed of protein and nucleic acid (DNA or RNA).
Characteristics of Virus
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Viruses are non-living, infectious particles made up of either DNA or RNA, as well as a protein coat.
- They are found in almost every environment across the globe, including the ocean, soil, and even in the clouds.
- Although they don't have any metabolic capabilities or organelles, they do have an outer coating surrounding their genetic material.
- This protein coat has certain characteristics that let us identify whether or not it is a virus.
- They lack the cellular machinery and life processes of the host cells into which they manage to get by accident or design.
- They tend to vary from one species to another and depend upon the type of cells that they infect for sustenance.
Structure of Virus
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A Virus has a very simple kind of structure.
- They have an outer layer of protein cells which is made up of a genetic material DNA or RNA.
- They vary in different shapes like spherical, rod, etc.
- They do not have cytoplasm.
- They do not grow.
- They are acellular microorganisms, which means they lack cells.
Structure of virus
Read: Difference Between Cytoplasm and Protoplasm
Difference Between Bacteria And Virus
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The differences between bacteria and virus are as tabulated below:
| BACTERIA | VIRUS |
|---|---|
| Single-celled | Non – cellular |
| They are larger in size as compared to virus | They are very small |
| Have metabolism of their own | Have no metabolism of their own |
| Take food by absorption | Take no food by any method |
| Grow in size and divide to produce more bacteria | Do not grow and do not divide |
| They can reproduce by their own | Command the host cell to reproduce virus |
| Cannot be crystallized | Can be crystallized |
| Some are harmless, some are useful and some are disease-causing. | All produce diseases in man, animals, and plants. |
| Cause localized infections | Cause systemic infection |
| Can be either beneficial or harmful | Usually harmful, though useful in genetic engineering |
| Infections can be prevented by antibiotics | Infections can be prevented by vaccines |
| Food poisoning, ulcers, pneumonia, tuberculosis, etc are examples of bacteria | AIDS, common cold, influenza, chickenpox, etc are examples of a virus. |
Things to Remember
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- Bacteria are one-celled organisms that take several shapes spheres, rods, spirals.
- They are found everywhere in the food, dirt, and on our bodies.
- Most Bacteria are good such as those that help with digestion.
- Viruses are particles that invade your body's cells.
- Antibiotics will not help a viral infection or stop the spread of a viral infection to others.
- Taking Antibiotics for viral infection can increase the chance of an antibiotic-resistant infection later.
Sample Questions
Ques. How does a virus differ from other microorganisms such as bacteria? (3 marks)
Ans. Viruses are much smaller in size than other microorganisms.
- They do not show most of the characteristics of living organisms such as respiration.
- They reproduce only inside the cells of the host organisms, which may be a Bacterium, plant, or animal.
Ques. What are the major groups of micro-organisms? (3 marks)
Ans. There are five major groups of micro-organisms:
- Bacteria
- Virus
- Protozoa
- Fungi
- Algae
Ques. Name any four diseases which can be prevented by vaccination? (3 marks)
Ans. Several diseases that can be prevented by vaccination include
- Tuberculosis,
- Smallpox,
- Cholera,
- Hepatitis.
Ques. What are micro-organisms? Give any two examples of micro-organisms. (2 marks)
Ans. The organisms which are too small to be seen by the naked eyes and can be seen only through a microscope are called micro-organisms or microbes. Bacteria and Viruses are examples of micro-organisms.
Ques. What are Antibiotics? (2 marks)
Ans. Medicines that can kill or stop the growth of the disease-causing micro-organisms are called antibiotics.
Streptomycin, tetracycline are some of the commonly known antibiotics which are made from Fungi and bacteria.
Ques. Describe how the curd is made from milk? Name the bacterium which converts milk into curd. (3 marks)
Ans. Bacteria Lactobacillus convert milk into curd. When a small amount of pre-made curd is added to the warm milk, then lactobacillus bacteria that is present in curd multiply in milk and convert it into curd. During this process, lactobacillus bacteria act on the lactose sugar present in milk and convert it into lactic acid. This lactic acid then converts milk into curd.
Ques. Explain various types of bacteria? (3 marks)
Ans. Bacteria are classified into different groups on the basis of their shapes. Bacteria are single-celled microorganisms occurring in large numbers and in a variety of shapes. They comprise rod-shaped bacteria, spherical bacteria, curved bacteria, and spiral bacteria. However, bacteria do not have a nucleus as do plant and animal cells but they contain genetic material (genes) enclosed in a membrane. Each bacterium is composed of thousands of proteins that perform specific functions.
Ques. Why tuberculosis is considered an infectious disease? (3 marks)
Ans. Tuberculosis or TB is well known as an infectious disease or pulmonary disease that develops when bacteria spread from one person to another via tiny droplets released into the air via cough or sneeze. TB is considered contagious because some symptoms of tuberculosis are common with those of a number of other diseases and the infected person cannot realize its existence inside his body. It is a long-term disease that needs proper treatment under the supervision of a doctor to treat it completely.
Ques. What is the role of bacteria in increasing soil fertility? (2 marks)
Ans. The nitrogen-fixing bacteria are called rhizobium, azotobacter, rhizospirillum, etc. These bacteria reside in the root nodules of the leguminous plant and can fix atmospheric nitrogen. This fixed nitrogen is used up by the plant and is an important source of essential nutrients in the soil.
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