microorganism

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1. learn science https://www.youtube.com/watch?v=-rfnCqrmaEQ&ab_channel=LearnScience copy past in youtube ® All rights reserved

2. learn science 1) A microorganism, or microbe, is a microscopic organism, which may exist in its single-celled form or a colony of cells. 2) The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from sixth century BC India. The scientific study of microorganisms began with their observation under the microscope in the 1670s by Antonie van Leeuwenhoek. In the 1850s, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In the 1880s, Robert Koch discovered that microorganisms caused the diseases tuberculosis, cholera, diphtheria, and anthrax. 3) Microorganisms include all unicellular organisms and so are extremely diverse. Of the three domains of life identified by Carl Woese, all of the Archaea and Bacteria are microorganisms. These were previously grouped in the two domain system as Prokaryotes, the other being the eukaryotes. The third domain Eukaryota includes all multicellular organisms and many unicellular protists and protozoans. Some protists are related to animals and some to green plants. Many of the multicellular organisms are microscopic, namely micro-animals, some fungi, and some algae, but these are not discussed here. ® All rights reserved

3. learn science 4) They live in almost every habitat from the poles to the equator, deserts, geysers, rocks, and the deep sea. Some are adapted to extremes such as very hot or very cold conditions, others to high pressure, and a few, such as Deinococcus radiodurans, to high radiation environments. Microorganisms also make up the microbiota found in and on all multicellular organisms. There is evidence that 3.45-billion-year-old Australian rocks once contained microorganisms, the earliest direct evidence of life on Earth. 5) Microbes are important in human culture and health in many ways, serving to ferment foods and treat sewage, and to produce fuel, enzymes, and other bioactive compounds. Microbes are essential tools in biology as model organisms and have been put to use in biological warfare and bioterrorism. Microbes are a vital component of fertile soil. In the human body, microorganisms make up the human microbiota, including the essential gut flora. The pathogens responsible for many infectious diseases are microbes and, as such, are the target of hygiene measures. ® All rights reserved

4. What are microorgranisms? learn science Microorgranisms are microscopic organisms that are not visible to nacked eye and can seen only using and instruments called a microscope. Microorgranisms (from Greek, ‘ micros’ meaning “small” ) may be either unicellular (i.e, made up of one cell) or multicellular (i.e, made up of more than one cell). ‘THE STUDY OF MICROORGANISMS IS KNOWN AS MICROBIOLOGY’. Microorgranisms make up largest number of living organisms on the planet. They are foung as free organisms or in group as colonies. They are found all aroung us-in air, soil, water, inside rocks, on the surface of plants and animals, and living inside them. The discovery of microorganisms can be attributed to two scientists: Robert Hooke, who discovered and described a fungus (1665); and Anton van Leeuwenhoek, who described bacteria and a few protists (1674). Before learning about the different types of microorganisms, let us first understand the structure of a microscope. ® All rights reserved

5. Microscope learn science A microscope is an instrument which is used to observe small objects by forming their magnified images with the help of lenses and light . [Fig. 2.1 (next page)] shows the parts of a typical microscope. In a compound microscope, the lens closer to the object is called the objective , while the lens closer to the eye is called the eyepiece . The object to be viewed is termed the specimen . It is arranged on a small rectangular piece of glass called a slide , which is covered by a thin square or round piece of glass called a cover glass or coverslip [Fig 2.2(next page)]. The slide can be fixed on the stage and the specimen can be viewed by arranging the objective lens over it and viewing it through the eyepiece lens. ® All rights reserved

6. Fig 2.1 and 2.2 learn science ® All rights reserved 2.2👆 👈2.1

7. Types Of Microorganisms Microorganisms can be divided into five major types: bacteria, protozoa, fungi, algae, and viruses. Each type has a characteristic cell structure, mode of nutrition, locomotion, and reproduction. BACTERIA Bacteria are unicellular microorganisms. They are one of the earliest forms of life on Earth. They have evolved over the years. Bacteria can withstand extreme temperatures (very hot or very cold). They are also able to utilize different substances such as sunlight, sulphur, and iron to produce their food. Bacteria are grouped into four groups based on their shapes (Fig. 2.2 below👇). Cocci (spherical in shape) Bacilli (rod-shaped) Spirilla (spiral in shape) Vibrio (curved or comma-shaped) vibrio learn science ® All rights reserved

8. learn science ® All rights reserved PROTOZOA Protozoa (from Greek, proto meaning “first” and zoon meaning “animal” ) are uncellular microorganisms too. They can be ovel, spherical, or elongated in shape. They feed on other tiny animals. Protozoa are found mostly in aquatic regions or in areas that are moist. Amoeba, Euglena, and paramoecium (fig. 2.4) are examples of protozoa. fig. 2.4 paramoecium viewed by microscope 👆 Fungi Fungi are a group of plants-like non green organisms that grown on decaying surfaces. They may be unicellular and microscopic, like yeast (Fig. 2.5), or multicellular and macroscopic, like mushroom. They come in different shapes and sizes. They get their nutrition from decaying plant and animal matter. Fungi are responsible for breaking down organic matter and relesing substances into the soil and the atosphere. Fungi can be found in many places such as rising bread, mouldy bread, and on forest floors fig 2.5 yeast viewed by microscope 👉

9. learn science Algae Algae are simple plant-like organisms that are usually aquatic Unlike other microbes, they contain chlorophyll, and therefore carry out photosynthesis. However, unlike plants algae do not have true roots, stems, or leaves. Algae can be found in freshwater or saltwater, and in damp and moist places. On land they may grow on rock surfaces, the bark of trees, in stagnant water, and on rotting wood. Algar range in size from unicellular microscopic forms, such as Chlorella. Chlamydomas, and distoms, to multicellular macroscopic forms such as marine seaweeds (Fig.2.6), for example, kelp Viruses Viruses (Fig. 2.7) are the simplest and tiniest of microorganisms and can only be seen with the help of a powerful microscope-the electron microscope Viruses cannot grow or multiply on their own. They need to enter a living cell to be able to multiply. That is why some scientists have classified viruses as non-living organisms. ® All rights reserved Fig. 2.6 seaweed is an example of algae Fig. 2.7 Representation of viruses

10. learn science ® All rights reserved Microorganisms are useful to us in many ways. The major areas where microorganisms are most commonly beneficial are the food industry, medical science, agriculture, and environment conservation. USEFUL MICROORGANISMS Microorganisms in The Food Industry Microorganisms are used in the food industry to prepare various food items such as yoghurt, bread, alcoholic beverages, and nutritional supplements. Preparing yoghurt The bacterium Lactobacillas is added to warm, pasteurized milk to make yoghurt. Cheese and paneer (or cottage cheese) are also produced using the bacteria Lactobacillus and Streptococcus . The fungus mould helps to flavour different kinds of cheese.

11. learn science ® All rights reserved Preparing bread Yeast is used in baking industries for making, breads, pastries and cakes. It produces alcohol and carbon dioxide by acting on the carbohydrates present in the dough of bread. Bubbles of carbon dioxide help the bread to rise, making it soft and fluffy, while the alcohol evaporates during baking (Fig. 2.8) Fig. 2.8 pores in bread formed by bubbles of carbon dioxide Preparing alcoholic beverages and other food items Yeast is used in the production of alcoholic beverages such as wine, beer, and whiskey. Yeast acts on the natural sugarsesent in barley, wheat, rice, and crushed fruit juices and converts them into alcohol. This process of converting sugar into alcohol is known as fermentation . The fermented mixture is purified, pasteurized, and stored in bottles. Yeast and bacteria such as Lactobacillus and Streptococcus are also used in preparing pickles, canned olives, sausages, chocolate, soya sauce, vinegar, and food items. Get It Right While there are more than 150 known species of yeast, the species Saccharomyces cerevisiae, known as baker’s yeast, is often used in the kitchen. Just one gram of yeast holds about 25 billion cells. That smount of fungi can produce signigicant amounts of carbon dioxide

12. learn science ® All rights reserved Beneficial bacteria, such as Lactobacillus acidophilus, Lactobacillos bulgaricus, and Bifidobacteria, can be introduced into the digestive system through foods called probiotics. Most fermented milk products such as yoghurt contain these bacteria and have probiotic properties. Nutritional supplements Certain algae, such as Spirulina and Chlorella, are rich in essential nutrients like proteins, vitamins, and some minerals, which are required by the body. These algae are taken as nutritional supplements, in the form of tablets or capsules to increase nutrient intake by the body.

13. ® All rights reserved Microorganisms In Medicine Microorganisms are of extensive use in medical science as they are used to produce antibiotics and vaccines. Antibiotics Whenever we visit the doctor for a serious illness, we may be prescribed antibiotics such as penicillin, streptomycin, and tetracycline. These medicines are made with the help of microorganisms such as the fungus Penicillium notatum and the bacterium Streptomyces . These microbes produce substances which weakens and destroy the growth of disease-causing microorganisms. Such medicines which are manufactured by growing specific microorganisms to cure various diseases are called antibiotics . learn science Vaccine Children are given vaccines over a period of around five years after they are born. This helps to protect them from diseases such as diptheria, tetanus, tuberculosis, and hepatitis. In many cases, adults too receive vaccinations against various diseases. Vaccines are preparations of weakened or killed disease causing microorganisms. When the vaccine is introduced into the body, it produces substances called antibodies to fight and kill disease carrying microbes. These antibodies also remember to do the same whenever that particular microbe enters the body in the future, thus ensuring protection against that particular disease. Vaccination is also used to protect animals from various diseases.

14. ® All rights reserved learn science Milestone Insulin is a hormone produced by the pancreas for the metabolism of sugar (or glucose) in the blood. People who produce a very low to almost negligible amount of insulin have high sugar levels in their blood, a condition called diabetes, Diabetic patients require insulin injections for metabolizing sugar present in their blood. Since the 1920s, insulin was being extracted from the stomach of animals such as pig and cattle. This animal insulin caused allergic reactions in human beings as it did not completely match with human insulin. With the rise in the number of diabetic patients and in a bid to produce chemically identical human insulin, scientists at City of Hope National Medical Centre in Duarte, California, collaborated with Genentech, a financial company, to produce human insulin using the bacterium E.coli (found in the human intestine) with the help of a process called recombinant DNA technology in 1978 Insulin synthesis was the first laboratory production using DNA technology and was carried out by the scientists Arthur Riggs and Keichi Itakura. This breakthrough has reduced the dependency on animal glands for insulin and the possibility of allergic reactions.

15. TECH BYTES ® All rights reserved learn science Biotechnology is the technology based on biology or biological systems. it incorporates the use of biological processes or organisms, mostly microorganisms, for commercial production or technology. Man has been using microbes for producing bread, wine, and cheese for centuries, thus employing biotechnology unknowingly. Recently, with the knowledge of cells and their internal functioning, mankind has also been able to study severe diseases such as cancer, organ failure, diabetes, heart problems, and even AIDS Scientists are able to come up with cures and preventive measures (such as vaccines) for many other diseases with the help of biotechnology

16. ® All rights reserved learn science Agricultural Use Certain microbes play an important role in agriculture mainly by carrying out nitrogen fixation. Nitrogen fixation Nitrogen in its atmospheric form cannot be used by plants. It needs to be converted into nitrogen-containing compounds for easy utilization by plants. The process by which nitrogen in the atmosphere is converted into compounds which can be used by plants and animals is called nitrogen fixation . As nitrogen is required by all forms of life including plants and animals, nitrogen fixation is essential. Rhizobium is a nitrogen fixing bacterium that is found in the roots of leguminous plants. It is able to fix atmospheric nitrogen into useful compounds, which can be used by plants to produce proteins When these plants are eaten by animals, the fixed nitrogen is used by them to make proteins and amino acids. After plants and animals die, decomposers act on the proteins amino acids to return nitrogen compounds back to the soil Chemical fertilizers also add nitrogen compounds in the soil These nitrogen compounds can be either taken up directly by plants through their roots, or converted to nitrate gases and released back into the atmosphere. These pases react with water in the atmosphere and return to soil through rainwater. Certain special bacteria present in the soil also help to return nitrogen back into atmosphere.

17. Which plants would require more fertilizers leguminous or non-leguminous plants? Why? ® All rights reserved learn science The nitrogen cycle is a continuous series of natural processes by which atmospheric nitrogen passes to the soil, and then to organisms, and back to air or soil, involving nitrogen fixation and decay. (Fig 2.10) shows a simplified representation of the nitrogen cycle in the form of a flowchart

18. ® All rights reserved learn science Environmental Use Many microtease help to keep the environment clean by acting as decomposers Decomposers Many macroorganisms including examples from bacteria, tung, and protozos, feed upon decaying rems dead organisms and are called decomposers. In the process called decomposition, these decomposers break down complex organic matter inte simple compounds They thus contribute to cleaning the environment by recycling enential elements that are trapped in tistics of dead ergans such that they can be used by plants and other organisms Microbes are important to the environment as they participate in the carbon and nitrogen cycles. They are also used in water prication, treatment of sewage dearung oil spills, and removing the pollutants of soil and water.

19. ® All rights reserved learn science Questions A. Fill in the blanks with the correct words. 1. Microscopic organisms that are not visible to the naked eye are called_________. (macroorganisms/microorganisms) 2 Microorganisms can be unicellular or______________. (non-cellular/multicellular) 3. Spirilla are one of the shapes of_______________. (bacteria/fungi) 4. Amoeba, Euglena, and Parumoecium are examples of_______________. (algae/protozoans) 5._____________(Decomposers/Nitrogen fixers) break down complex organic matter into simple compounds.

20. ® All rights reserved learn science Harmful Microorganisms Microorganisms can cause diseases in humans, animals, and plants. Disease causing microorganism are called pathogens , or germs , or infectious agents . Some microorganisms can even spoil food, clothing, and leather. Let us learn more about harmful microorganisms Disease-causing Microorganisms In Humans Pathogens can enter the body of a healthy person through various sources and cause diseases. The transmission of pathogens from a diseased individual to a healthy individual is called infection . Diseases are broadly classified into two groups. Non-communicable diseases are diseases that cannot be transmitted from one person to another . They develop when the body is not functioning properly. Examples are cancer, diabetes, nutrient deficiency diseases, allergies, and mental illness. Communicable diseases are diseases that spread from infected persons to healthy ones . Examples are chickenpox, common cold, tuberculosis, typhoid, and cholera. The germs that cause communicable diseases are transmitted through the following methods.

21. ® All rights reserved learn science Direct contact : A healthy person can contract a disease when he or she comes in contact with an infected person, or uses articles that are used by the infected person. Diseases caused in this way are ringworm, measles, mumps, chickenpox (Fig. 2.11) and athlete's foot (Fig. 2.12). Fig. 2.11 Child with chickenpox Fig. 2.12 Athlete’s foot Droplet infection : A healthy person can contract a disease when he or she inhales germs through droplets of moisture, which have been coughed or sneezed out by an infected person. Examples of diseases caused in this way are common cold and flu.

22. ® All rights reserved learn science Contaminated food and water : A healthy person can contract a disease by consuming unclean or undercooked food and water. Examples of diseases caused in this way are cholera and diarrhoea. Food becomes unclean or contaminated when some animals spread germs from garbage and faeces to food. Such animals that transmit pathogens from garbage to food are called carriers . Houseflies and rat fleas are examples of carriers. Diseases caused by carriers include typhoid and plague. Vector-borne : A healthy person can contract a disease when he or she is bitten by an animal or insect carrying the pathogen. Examples of diseases caused in this way are malaria (the vector is the female Anopheles mosquito), dengue (the vector is the female Aedes mosquito), and rabies (transmitted by the bite of an animal affected with rabies). Untreated wounds : Pathogens can enter the body through untreated or uncovered wounds or sores. Tetanus is a disease contracted in this way . Usually, the immune system of a healthy person develops immunity to some common infections and helps the body fight pathogens. Vaccinations too help in building the body's defense. Antibiotics, antiseptics, disinfectants, and fungicidal chemicals are used to kill microorganisms and prevent the ad of diseases

23. ® All rights reserved learn science Examples of common diseases that occur in human beings, along with their mode of transmission, and preventive measures, are given in Table 2.1 below

24. ® All rights reserved learn science Applying huic hygiene in daily life can also help to prevent the spread of harmful microorganisms. Good habits include washing our hands with soap before and after eating or preparing food and after using the toilet, brushing teeth regularly, covering our mouth while coughing or sneezing, avoiding contact with an infected person, avoiding consumption of uncooked or stale food; and storing uncooked meat away from other food items. Disease causing Microorganisms In Animals Examples of animal diseases caused by microorganisms are listed in Table 2.2 below. Disease Type of microorganism mode of transmission transmission animal affected Fin rot Bacteria/ Fungi Dirty water, injury Fish Anthrax Bacteria Grazing Cattle Foot and mouth Disease Virus Air, contact with an infected animal Cattle

25. ® All rights reserved learn science Disease-causing Microorganisms In Plants Several microorganisms cause diseases in plant including grains, vegetables, and fruits. These diseases affect the yield of crop and can be controlled by the use of chemicals which kill the microorganisms. Examples of common plant diseases caused by microorganisms are given in Table 2.3 below. Disease Type of microorganism Mode of transmission Plant affected Rust of wheat Fungi Infected seeds and insects Wheat 🌾 Apple scab Fungi Air Apple 🍏 Ear rot Bacteria Air Wheat 🌾, maize 🌽 Leaf rolls Virus Insect, Air Tomato 🍅

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28. Recap ® All rights reserved learn science Microorganisms can be of five types: bacteria, protozoa, fungi, algae, and viruses. Useful microorganisms are used for various purposes such as preparing various food items, medicines, in agriculture, and in keeping the environment clean. Harmful microorganisms cause diseases in human, animals, and plants. They also spoil food. Some of the diseases caused by microorganisms in human beings are malaria, cholera, typhoid, measles, and chickenpox.

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