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Microbes are certain organisms that are not visible to the naked human eye. These organisms are also called microorganisms, and such organisms can only be seen with the help of a microscope. The term microbes in itself is very wide in nature and its usage is very general, and it is used to describe organisms like bacteria, archaea, fungi, protista, viruses, and certain other organisms which are microscopic in nature. Microbes can be found almost everywhere, in fact, the human body is a very good home to such organisms. Microbes or microorganisms is a general term which is used to comprise both microscopic animals and microscopic plants. Microscopic plants are not usually found on the human body.
Read more: Compound microscope
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KeyTerms: Microbes, prokaryotes, animals, plants, bacteria, fungi, virus, human body, Human eye, protista
Microbes
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Microbes are tiny, single-celled organisms that are not visible to the human eye. They are also referred to as microbes or microscopic organisms because a microscope is the only way to see them. They account for roughly 60% of all living things on earth.
Types of microbes
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There are several different types of microbes found on Earth, some of which are discussed below:
Bacteria
Bacteria are unicellular microbes and are prokaryotic in nature. Bacteria survive in different situations, some survive in hot environments while others prefer cold, some need oxygen while others may not. Most of them are smaller than human body cells and they have no nucleus.
Bacteria
- They do not have any other membrane wrapped organelle, although they do consist of an outer membrane.
- Bacteria are very diverse and they exist in multiple shapes, forms etc.
- Reproduction in bacteria occurs through binary fission.
- They are not necessarily harmful to the human body, instead are actually important for human bodies as they play a vital role in the digestive system
- They help boost the immunity system.
- A very minimal type of bacteria can be responsible for causing infections to the human body.
- Bacteria can be treated with antibiotics, although when bacteria mixes with virus antibiotics would not be of any help as they are resistant to antibiotics.
Archaea
Just as bacteria, archaea are also single celled microbes. Similarly as bacteria, they are prokaryotic, which means they do not have any cell nucleus or any membrane wrapped organelle. During the early stages of its discovery, archaea were often categorized with bacteria because of the similarities they share.
Archaea
- They exist in different forms and structures, which further increases the confusion between them and bacteria.
- But there are some fundamental factors which help differentiate between archaea and bacteria.
- Cell membranes of bacteria are made up of phosphoglycerides while archaea membranes are made of ether lipids.
- This type of lipid is not found in any other form of organism.
- Archaea may also have a cell wall, which is fundamentally different from that found in bacteria.
- It is noticeable that there are fundamental differences in the biochemistry and genetics of archaea and bacteria.
Virus
Unlike the microbes discussed in the previous headings, viruses do not have any cells of their own. They can either be made of nucleic acid, protein or even lipids in some cases.
Virus
- Viruses have molecules which are surrounded by protein shells.
- Because they do not have any cells of their own, they are living organisms in the stricter sense.
- They reproduce by invading other cells and taking over the host's cellular machinery.
- The speciality of viruses is to invade a host, and they may even choose a particular cell to invade such a host.
- They do not reproduce on their own and do not have their own cells, it has often been debated whether viruses should be categorized as living organisms or not.
- Viruses can affect plants, animals, bacteria, archaea, primates etc.
Microscopic animals and plants
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Microscopic animals are multicellular organisms, and they have different cells which are designed for different performing functions. They have nuclei and cell membrane wrapped organelle, unlike the organisms mentioned above. They do not necessarily have a rigid cell wall. Examples of microscopic animals are arthropods, crustaceans, and rotifers. Most microscopic animals cannot live on the human body, with mites being an exception.
Microscopic plants are also considered microbes. This term is often used synonymously with the term green algae. These are single celled organisms and have membrane wrapped organelle. They have both an outer membrane and a cellulose cell wall. Unlike microscopic animals, they can make their own food. They do not live in the human body. Microscopic plants are very essential for nature, mostly because they release oxygen, which is essential for animal survival.
Read more:
| Relevant Concepts | ||
|---|---|---|
| Biodiesel | Cyanobacteria | Eubacteria |
| Structure of RNA | Glycolipids | Harmful microorganisms |
Applications of Microbes
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Microbes are important in human nature and for human health as well. Some of the applications are as follows:
- These organisms are very useful in fermentation of meals, treating the sewage, and production of important substances like fuel enzymes etc.
- They are also useful in production of certain other bioactive substances.
- Microbes have also been used in the military field through biological warfare and bioterrorism.
- Microbes are also an important part of the soil on earth.
- The microorganisms that are found on the human body are responsible for the composition of the human microbiota which includes the vital intestinal flora, essential for human survival.
- Microbes are also responsible for various infections and diseases because of their pathogenic nature, and because of this, they are also targeted during hygienic efforts.
- Microbes can be very diverse, as they include all single celled organisms from all three forms of life.
- Microorganisms are important in the production of foods, the treatment of wastewater, the production of biofuels, and the production of a wide range of compounds and enzymes.
Things to Remember
- They have been turned into weapons and occasionally used in bioterrorism and hostilities.
- They are essential to agriculture because of their involvement in soil fertility and organic matter decomposition.
- Plants, animals, bacteria, archaea, primates, etc. can all be affected by viruses.
- Phosphoglycerides make up the cell membranes of bacteria, whereas ether lipids make up the cell membranes of archaea.
- Few types of microorganisms are bacteria, archaea and viruses.
- Microbes account for about 60% of living organisms on earth.
Sample Questions
Ques. What is the use of antibiotics in medicine? (2 marks)
Ans. Antibiotics are made up with the composition of those microbes that hold the ability to either kill to limit the growth of infection causing microbes inside the human body. Antibiotics have been very useful to human life as they help fight many diseases like plight, cough, leprosy etc.
Ques. How are microbes involved in secondary wastewater treatment? (4 marks)
Ans. Secondary wastewater treatment is also called the biological approach.
- This is because in this approach breakdown of organic matter is done with the involvement of microbes.
- Primary effluents are also used and passed through aeration tanks.
- During this the organic matter contained in the aeration tanks is absorbed by microbes and later digested by anaerobic fungi and bacteria.
Ques. Compare simple and facilitated diffusion. (2 marks)
Ans. The major distinction between simple and facilitated diffusion is the mode by which molecules get transported over the cell membrane. In simple diffusion there is direct transportation as allowed by the cell membrane while in facilitated diffusion transportation occurs with the help of transmembrane proteins.
Ques. What are fermenters? (2 marks)
Ans. Fermentors, also known as bioreactors, are sterile and enclosed tanks used for the optimum development of microorganisms. The bacteria may be cultured in huge quantities to create commercially useful metabolites. Fermentors are outfitted with heating, mixing, and aeration components. Its capacity can range from 500,000 liters for industrial usage to 1 mL for laboratory use.
Ques. How do microorganisms spoil food? (2 marks)
Ans. Microbes like fungi and bacteria can cause spoilage of food which is also known as microbial spoilage. In such spoilage, the microbes grow on the food and in the process create certain substances which change the color, texture, and odor of the host food element. As they keep on growing, the food becomes unfit for consumption.
Ques. Explain the discovery of penicillin. (2 marks)
Ans. Penicillin was discovered by Dr. Alexander Fleming in 1928 when he was returning from a holiday and found a mold growing on Staphylococcus bacteria. He observed that this mold was preventing the bacteria surrounding it from growing. He observed that this mold acts as a self defense chemical and can kill bacteria and subsequently named in bacteria.
Ques. What are the uses of Nuclear Polyhedrosis Virus? (3 marks)
Ans. Nuclear Polyhedrosis Virus is a part of the baculoviruses family.
- It has the ability to affect insects, moths and butterflies in particular.
- Its major use has been that as a pesticide.
- It has insecticidal applications as a result of which they have no negative effect on mammals, plants etc.
Ques. What is the significance of enzymes in detergents used for washing clothes? (3 marks)
Ans. Enzymes are catalysts that speed up chemical reactions in a number of biological processes such as digestion and growth. Commercial enzymes are employed in the detergent industry to improve stain removal, whiteness, fabric and color care, and overall cleaning performance. Lipases obtained from microbes are used in such detergents which helps in breakdown of oil and help in cleaning.
Ques. What is the role of microbes in decreasing environmental degradation? (4 marks)
Ans. Some of the role of microbes includes:
- Microbes are essential in helping reduce environmental degradation by chemicals.
- Microbes can be used both as fertilizers and pesticides and also biofertilizer and biopesticides.
- They can help improve soil properties.
- They are also used for their biocontrol applications in many cases.
Ques. Mention useful applications of bacteria (5 marks)
Ans. Bacteria are very important for human life and human survival. Few applications are as follows:
- They help cause the decomposition of organic matter through the process of fermentation.
- They also enrich soil properties by fixing its nitrogen.
- They are also used in medicine in the form of antibiotics, serums, vaccines.
- Bacteria have been used by man for a variety of industrial reasons.
- The dairy sector is entirely dependent on microbes.
- Souring and curdling of milk are done by lactic acid bacteria.
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