MICROORGANISMS FRIEND and FOE Basic lesson Plan Class Subject Lesson Teacher School Date Classes
: VIII : Biology : 2. Microorganisms: friend and foe : Mrs. Rasika Gore : National Public School, Yelahanka : 28th May 2019 : 10
Learning Objectives • To help students learn how some microorganisms can help us while few micro-organisms are harmful to us Basic concepts / Ideas: 1.Microorganisms Classification of microorganisms Bacteria, Fungi, Protozoa, Algae, Virus Habitat of microorganisms Usefulness of microorganisms Diseases caused by microorganisms in animals and plants 2. Food Preservation 3. Nitrogen-Cycle
Concepts / learning outcomes • • • • • • • • • • • • • • •
Uses and harms of microorganisms. How micro-organisms help in making curd, bread, medicines, wine? What are viruses? Usefulness of micro-organisms in improving soil fertility. Diseases cause by micro-organisms in living organisms. Methods of food-preservation. What converts milk into curd? Use of fermentation in daily life. Who discovered vaccine and how it works? How do diseases spread from one person to another? What are antibiotics? How can we preserve food for a longer period? How nitrogen makes soil fertile? To analyse whether microorganisms are friend or foe. Stories behind discoveries- vaccines, fermentation, pasteurization, etc.
• • • • • • • • • • • • • • • • • • • • •
Microorganisms/microbes Microbiology Bacteria Fungi Protozoa Virus Biological nitrogen fixers Fermentation Vaccines Vaccination Communicable diseases Pathogens Carriers Preservatives Pasteurisation Leguminous plants Soil fertility Antibodies Antibiotics Eradication Algae
Key Words
Period wise distribution Period
Content
1.
Introduction, Discussion about understanding of microbes with students
2.
Microorganisms and its classification Algae, Bacteria, Fungi, Protozoa Virus
3.
Friendly microorganisms Food, Agriculture, Soil fertility, Cleaning environment, Medicines
4.
Friendly microorganisms- Vaccines (Medicines)
5.
Friendly microorganisms- Antibiotics (Medicines)
6.
Harmful microbes, Microbes causing disease in humans, animals and plants
7.
Food spoilage, Food poisoning, Food preservation
8.
Nitrogen fixation, Nitrogen cycle
9. 10.
Class test Review and closing
P1:Introduction (understanding students concepts)
Why does food get spoiled if kept for long duration? Why do we catch cold quickly if we are in contact with an infected person? What converts milk into curd? What happens to the moist chapatti/bread slice kept in open for 2-3 days? Why do we add baking soda/yeast during baking? Why are small children given with Polio drops after regular intervals? Have you used antibiotics? How can we preserve food for longer time? Benefits of food preservation? What food does your grandma/mother preserves? Why do we boil milk before using it? Why are we advised to keep the food items covered? Which food items are rich in proteins? Have you observed sick animals or plants? What are legumes? What are communicable and non communicable diseases? Which vaccines have you taken?
P2:Microorganisms, habitat and classification Organisms that are so small that they can only be seen through a microscope are called microorganisms or microbes. The study of microorganisms is known as microbiology. Most organisms are hardy and can be found in almost any kind of environment (omnipresent) – hot desert, polar ice caps, salt water, marsh lands, inside other organisms including humans, hot water springs. Some microorganisms grow on other organisms while others exist freely or in colonies. (Activity-2.1 Microscopic observation of muddy /dirty water and permanent slides of microbes) Types of microorganisms: There are four major groups of microorganism. These are as follows:
Bacteria Algae Protozoa Fungi
Viruses
Bacteria • They are simple living organisms which are found all around us. • They are mostly single cell organisms, but they live together in colonies of millions. • Bacteria are found in three different shapes: Bacilli : Rod or sausage shaped Cocci : Spherical or round shaped Spirilla : Spiral shaped Diseases: Typhoid - Salmonella. typhi (humans) Tuberculosis (TB) - Mycobacterium. Tuberculosis (humans) Citrus canker – Xanthomonas. axonopodis pv. citri (oranges) Anthrax – Bacillus. anthracis (humans and cattle)
Salmonella. typhi
Mycobacterium. tuberculosis
Algae • Algae are simple plant- like organisms which are usually aquatic in nature. • They contain a cell wall and chlorophyll and can make their own food by photosynthesis. • Algae can be unicellular or multicellular. Ex: diatoms, chlamydomonas, spirogyra, seaweed, etc. Spirogyra
Diatoms
Azolla
Protozoa • These are unicellular microscopic organisms similar to animals that can move about to capture food and are heterotrophic in nature. • They are mostly aquatic in nature. • Ex: amoeba, paramecium • Human disease Dysentery- Entamoeba. histolytica Malaria- Plasmodium (P. falciparum, P. malariae, P. ovale and P. vivax.) Amoeba
Paramecium
Giardia. lamblia
Entamoeba .histolytica
Plasmodium. falciparum
Plasmodium.falciparum invading RBCs
Fungi • Fungi are plant like organisms that do not contain chlorophyll. • They may be unicellular (yeast) or multicellular (bread mould) and are found in warm and moist places. • Fungi can be heterotrophic, saprophytic or parasitic in nutrition. • Ex: Yeast, Rhizopus (Bread mould), mushrooms, puffballs, morels • Human disease
Morels
Rhizopus
Yeast
Puff balls Mushrooms
Virus • Viruses are smaller than any known cell and can only be seen with electron microscope. • Viruses can reproduce only inside the bodies of other organisms, which mean they need a host (bacterium, plant or animal) and it is like a non-living thing outside the body of other organisms. Therefore, it is a borderline between a living and a nonliving thing. • Diseases Chicken pox Flu- Influenza Virus Polio/ Poliomyelitis- Poliovirus Chicken Pox- Varicella-Zoster Virus (VZV) HIV- Human Immunodeficiency Virus Foot-and-mouth disease (FMDV) Cucumber mosaic virus (CMV) Polio Virus Influenza Virus
FMDV
CMV
CMV
FMDV
VaricellaZoster Virus
Polio Virus
P3: Friendly microorganisms 1. 2. 3. 4.
In food and beverage industry In agriculture In cleaning the environment In making medicines (vaccines and antibiotics)
In food and beverage industry • Lactobacillus is a bacterium that sours milk and is used to prepare curd from milk. (Activity-2.2 Curd making)
• Fungi like mushrooms and morels are edible and are rich source of protein.
• Yeast is used in preparing food items like bread and cakes. (Activity-2.3 Dough making using yeast and flour)
• Yeast is also used in breweries for making alcohol, wines and acetic acid (commercial use) by the process of fermentation (conversion of sugar into alcohol). Yeast is grown on natural sugars present in grains like barley, wheat, rice, crushed fruit juices, etc. (Activity-2.4 Alcohol preparation using sugar solution and yeast)
Louis Pasteur discovered fermentation in 1857
Pasteur, Louis (1822-1895), worldrenowned French chemist and biologist, who founded the science of microbiology, proved the germ theory of disease, microbial fermentation, invented the process of pasteurization, and developed vaccines for several diseases, including rabies. He is know as “father of modern microbiology”. Undoubtedly Anton van Leeuwenhoek is the “father of microbiology” because he was the first person to observe bacteria and other microorganisms under microscope devised by himself.
In agriculture • Some bacteria (Rhizobium) and blue green algae (Nostoc) live in the root nodules of plants such as gram, pea (leguminous plants) etc. These bacteria absorb the nitrogen from the atmosphere and convert it into nitrate which serves as natural fertilizers for plants, hence, enhancing soil fertility. • These microbes are commonly called as biological nitrogen fixers. Rhizobium
Root nodules
Nostoc
Root nodules Rhizobium
In cleaning the environment • The microorganisms decompose dead organic waste of plants and animals converting them into simple substances. These substances are again used by other plants and animals. • Thus, microorganisms can be used to degrade the harmful and smelly substances and thereby clean up the environment. • The plant waste can be converted into manure by the action of microbes. The nutrients released in the process can be used by the plants again. (Activity-2.5 Making manure using plant waste, fruit and vegetable peels vs. plastic waste, e-waste)
P4: In making medicines - vaccines • When a disease-carrying microbe enters our body, the body produces antibodies to fight the invader. • The body also remembers how to fight the microbe if it enters again. • So, if dead or weakened microbes are introduced in a healthy body, the body fights and kills them by producing suitable antibodies. • The antibodies remain in the body and we are protected from the disease-causing microbes. This is how a vaccine works. • Diseases like cholera, tuberculosis, smallpox and hepatitis can be prevented by vaccination. • Vaccines are available in the nearby hospitals • These days vaccines are made on a large scale from microorganisms to protect humans and other animals from several diseases. (Activity-2.6 Prepare a chart of vaccines you have taken since childhood with the help of your parents)
Discovery: Edward Jenner discovered the vaccine for smallpox in 1798 Edward Jenner is known as the “Father of Immunology”. He was an English scientist and is famous for his discovery of the smallpox vaccine. This was the first successful vaccine ever to be developed and remains the only effective preventive treatment for the fatal smallpox disease. His discovery was an enormous medical breakthrough and has saved countless lives. In 1980, the World Health Organization (WHO) declared smallpox an eliminated/eradicated disease.
P5: In making medicines-antibiotics • Antibiotics are medicines which kill or stop the growth of the diseasecausing microorganisms. • A number of antibiotics are being produced from bacteria and fungi. Ex: Streptomycin, tetracycline, erythromycin • Antibiotics are mixed with the feed of livestock and poultry to check microbial infection in animals. • They are also used to control many plant diseases. • Antibiotics are not effective against cold and flu as these are caused by viruses. Note: Antibiotics should be taken only on the advice of a qualified doctor and the prescribed course should be completed. If taken unnecessarily it may kill the beneficial bacteria in the body. If taken when not needed or in wrong doses make them less effective when you might need it in future.
The story of penicillin actually began in 1929 with Alexander Fleming, a doctor and researcher at St. Mary's Hospital, London. Returning to his basement laboratory at the hospital after having been on holiday, he found an unwashed petri dish in which mould had been contaminated by streptococcus. Significantly, Fleming realised that the white ‘halo,’ surrounding the mould was killing off this common infectious bacterium, an important discovery. However, as crucial as this moment was, revisionists have now placed Fleming as one of the many scientists who discovered the ‘wonder drug’ but failed to realise its full potential. This view is supported by an experiment Fleming conducted where he added penicillin extract to blood in a test tube. It seemed inactive but this was because he had failed to isolate the penicillin correctly. Fleming published his discovery but it ultimately fell to others to further develop the uses of the drug, an aim which was soon to be driven forward by the extraordinary circumstances created by the Second World War. It was Australian scientist Howard Florey (1898-1968), German biochemist Ernst Chain (1906-79) and Norman Heartley (1911-2004) that led Boots Pure Drug Company to further experiments with penicilin as part of the British war effort.
“I did not invent penicillin. Nature did that. I only discovered it by accident.”
The simple discovery and use of the antibiotic agent has saved millions of lives, and earned Alexander Fleming – together with Howard Florey and Ernst Chain, who devised methods for the large-scale isolation and production of penicillin – the 1945 Nobel Prize in Physiology/Medicine.
P6: Harmful microorganisms Some of the microorganisms cause diseases in human beings, plants and animals. Such disease-causing microorganisms are called pathogens.
In Humans • Pathogens enter our body through the air we breathe, the water we drink or food we eat. • They can also get transmitted by direct contact with an infected person or carried through an animal. • Microbial diseases that can spread from an infected person to a healthy person through air, water, food or physical contact are called communicable diseases. Ex: common cold, chicken pox, tuberculosis.
Preventing the spread of communicable diseases Some simple methods of limiting the spread of communicable diseases are: To keep the infected person separated from others & to advice him/ her to keep a handkerchief on the nose and mouth while sneezing/coughing. To keep our environment or surrounding clean. Never let garbage collect in the neighbourhood. Segregating dry and wet waste. Timely vaccination against diseases should also be taken. To prevent mosquitoes from breeding we should not allow water to collect anywhere in our neighbourhood, flower pots, plastic tanks, tyres, buckets, etc.
Avoiding communicable diseases - Don'ts
Avoiding communicable diseases - dos
Problems
Solutions
When a person suffering from common • We should keep a handkerchief on the cold sneezes, fine droplets of moisture nose and mouth while sneezing. carrying thousands of viruses are spread • It is better to keep a distance from infected persons. in the air. The virus may enter the body of a healthy person while breathing spreading the disease. There are some insects and animal which • Always keep food covered. act as carriers of disease causing • Avoid consuming uncovered items of food. microbes. Housefly is one such carrier. The flies sit on the garbage and animal excreta. Pathogens stick to their bodies. When these flies sit on uncovered food they may transfer the pathogens. Whoever eats the contaminated food is likely to get sick. Female Anopheles mosquito is a carrier • All mosquitoes breed in water. Hence, which carries the parasite of malaria. one should not let water collect Female Aedes mosquito acts as carrier anywhere, in coolers, tyres, flower pot, of dengue virus. etc. • By keeping the surroundings clean and dry we can prevent mosquitoes from breeding.
Human disease
Tuberculosis Measles Chicken Pox Polio
Causative microbes
Bacteria Virus Virus Virus
Mode of transmission
Air Air Air/Contact Air/Water
Cholera
Bacteria
Water/Food
Typhoid
Bacteria
Water
Hepatitis A
Virus
Malaria
Protozoa
Water
Mosquito
Preventive measures (General) • Keep the patient in complete isolation. • Keep the personal belongings of the patient away from those of the others. • Vaccination to be given at suitable age.
• Maintain personal hygiene and good sanitary habits. • Consume properly cooked food and boiled drinking water. • Vaccination. • Drink boiled drinking water. • Vaccination. • Use mosquito net and repellents. • Spray insecticides and control breeding of mosquitoes by not allowing water to collect in the surroundings.
In Animals Anthrax Host: Humans, cattle Pathogen: bacteria (Bacillus . anthracis )
Foot and mouth disease Host: cattle Pathogen: virus Foot-and-mouth disease virus (FMDV)
Discovery: Robert Koch (1876) discovered the bacterium Bacillus anthracis which causes anthrax disease. The German doctor Robert Koch is considered the founder of modern bacteriology. His discoveries made a significant contribution to the development of the first ‘magic bullets’ chemicals developed to attack specific bacteria - and Koch was awarded a Nobel Prize in 1905. Koch developed a new experimental method to test whether a particular micro-organism is the cause of a disease. Building on Pasteur's work on germ theory, Koch used experiments to prove that the bacterium Bacillus anthracis was the cause of anthrax - the bacterium could be observed in the tissue of anthrax victims. He extracted this bacterium from a sheep which had died of anthrax, grew it and injected a mouse with it. The mouse developed the disease as well. Koch repeated this process over 20 generations of mice, before he announced in 1876 that he had proved this bacterium caused anthrax.
In Plants • Microorganisms cause diseases in plants like wheat, rice, potato, orange, sugarcane, apple and others. • The diseases reduce the yield of crops. • They can be controlled by the use of certain chemicals which kill the microbes.
Plant diseases
Microbes
Mode of transmission
Citrus canker
Bacteria
Air
Rust of wheat
Fungi
Yellow vein mosaic of bhindi (Okra)
Virus
Air
Insect
P7: Food spoilage, food poisoning • • • •
Microorganisms spoil our food. Spoiled food emits bad smell and has a bad taste and colour change. Spoiling of food is a chemical reaction Food poisoning could be due to the consumption of food spoilt by some microorganisms. • Microorganisms that grow on food sometimes produce toxic substances. These make the food poisonous causing serious illness and even death.
Colour change Bad odour Taste change
Food preservation • Processing of food to prevent their spoilage and to retain their nutritive value for longer period is called food preservation. • Preservatives: The common chemicals generally used to prevent the growth of microorganisms. Ex: salt, sugar, edible oil, acids, etc. • Food can be preserved using many methods: 1. Chemical method Standard preservatives (recognized safe by national food agencies) Salt Sugar Oil and Vinegar 2. Heat and cold treatments Pasteurization 3. Storage and packing
Chemical method • Sodium meta bisulphite, Sodium benzoate - prevent the attack of microbes. Usage: Jam, squashes, sauces, ketchup, etc.
• Salt - prevent the growth of bacteria Usage : Meat, fish, amla, raw mangoes, tamarind, etc.
• Sugar - reduces the moisture content which inhibits the growth of bacteria which spoil food. Usage : Jams, jellies, squashes, etc.
• Oil and Vinegar - bacteria cannot live in such an environment. Usage : Vegetables, fruits, fish, meat, pickles, etc.
Heat and cold treatments • • •
Boiling kills many microorganisms. Low temperature in refrigerator inhibits the growth of microbes. Pasteurisation Pasteurised milk can be consumed without boiling as it is free from harmful microbes. Milk is heated to about 70°C for 15 to 30 seconds and then suddenly chilled and stored. This process prevents the growth of microbes.
Discovery: Louis Pasteur - Pasteurisation. Pasteurization, heat-treatment process that destroys pathogenic microorganisms in certain foods and beverages. It is named for the French scientist Louis Pasteur, who in the 1860s demonstrated that abnormal fermentation of wine and beer could be prevented by heating the beverages to about 57° C (135° F) for a few minutes . Pasteurization of milk, widely practiced in several countries, notably the United States, requires temperatures of about 63° C (145° F) maintained for 30 minutes or, alternatively, heating to a higher temperature, 72° C (162° F), and holding for 15 seconds (and yet higher temperatures for shorter periods of time). The times and temperatures are those determined to be necessary to destroy the Mycobacterium tuberculosis and other more heat-resistant of the non-spore-forming, disease-causing microorganisms found in milk. The treatment also destroys most of the microorganisms that cause spoilage and so prolongs the storage time of food. Ultra-high-temperature (UHT) pasteurization involves heating milk or cream to 138°to 150° C (280° to 302° F) for one or two seconds. Packaged in sterile, hermetically sealed containers, UHT milk may be stored without refrigeration for months. Ultrapasteurized milk and cream are heated to at least 138° C for at least two seconds , but because of less stringent packaging they must be refrigerated. Shelf life is extended to 60–90 days. After opening, spoilage times for both UHT and ultra pasteurized products are similar to those of conventionally pasteurized products. Pasteurization of some solid foods involves a mild heat treatment, the exact definition of which depends on the food. Radiation pasteurization refers to the application of small amounts of beta or gamma rays to foods to increase their storage time.
Storage and Packing Air tight packaging - Sealed air tight packets prevent the attack of microbes. Usage: Dry fruits, fruits, vegetables, etc.
Canning - It is done for packaging and to preserve food or drink by putting them in sealed, airtight containers. Used for: Olives, dill cucumbers, etc.
Drying - Dehydration of food removes excess water from it. This stops microorganisms from growing as they cannot grow without water. Usage: Papads, dried fish, dried meat, etc.
P8: Nitrogen Fixation • Rhizobium is involved in the fixation of nitrogen in leguminous plants. It lives in the root nodules of leguminous plants such as beans and peas, with which it has a symbiotic relationship. • Nitrogen also gets fixed through the action of lightning. • The amount of nitrogen in the atmosphere remains constant. • Our atmosphere has 78% nitrogen gas. Leguminous plants (pods)
Leguminous plants (pods)
Root nodules
Root nodules Rhizobium
Rhizobium
Lightning
• Our atmosphere has 78% nitrogen gas. • Nitrogen is one of the essential constituents of all living organisms as part of proteins, chlorophyll, nucleic acids and vitamins. • The atmospheric nitrogen cannot be taken directly by plants and animals. • Certain bacteria and blue green algae present in the soil fix nitrogen from the atmosphere and convert it into compounds of nitrogen. • Once nitrogen is converted into these usable compounds, it can be utilised by plants from the soil through their root system. • Nitrogen is then used for the synthesis of plant proteins and other compounds. • Animals feeding on plants get these proteins and other nitrogen compounds • When plants and animals die, bacteria and fungi present in the soil convert the nitrogenous wastes into nitrogenous compounds to be used by plants again. • Certain other bacteria convert some part of them to nitrogen gas which goes back into the atmosphere. As a result, the percentage of nitrogen in the atmosphere remains more or less constant.
Home work
• • •
Page 29, 30 NCERT Science text book Activities : 2.2 to 2.6 Prepare a factsheet about scientist and their discoveries using points below: Birth, Nation Profession Invention/discovery Year of invention/discovery History/Story behind their invention Nobel prize details if received, field in which Nobel prize was received Pioneer of any subject (Ex: Father of Microbiology) Your opinion on how is the invention/discovery useful to you/mankind in the 21st century?
P9: Class test 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.
What are micro-organisms? Name and describe the different kinds of micro-organisms with examples Name a few diseases caused by bacteria, fungi, virus and protozoa in living organisms? Where can we find micro-organisms? Name the bacteria which help to convert milk into curd. Define fermentation? Who discovered penicillin? Who discovered the vaccine for small pox? What are communicable diseases? How can we avoid them? Name the diseases caused by mosquitoes? Name a few plant diseases caused by micro-organisms. What causes food poisoning? What is pasteurization? Name the bacteria which help to fix atmospheric nitrogen. What id nitrogen cycle? Why do we segregate dry and wet waste? Describe the methods of food preservation? How are microbes useful to mankind in day today life? Explain it giving examples in detail?
P10: Review and Closing • • • •
Doubt clearing Discussing activities result Discussing homework Discussing class test
References • NCERT : Science, Class 8th textbook, Chapter 2, Microorganisms: Friends and Foe(Pg. no 17-31) • https://www.georgianjournal.ge/society/33572-georgian-student-who-paints-withbacteria-earns-third-place-at-microbiology-art-contest.html • https://www.britannica.com/biographies • Google images- https://www.google.com/imghp?hl=en
