SCIENCE MICROORGANISIM- FRIENDS OR FOES NOTES

DAV PUBLIC SCHOOL, SECTOR-VI, DWARKA

NOTES

CLASS – VIII

MICROORGANISIM- FRIENDS OR FOES

What are Microorganisms?

Tiny organisms , microscopic, living, single-celled organisms which can’t be seen with unaided eye.

Micro-organisms are of great importance to the human health , to environment, and to our economy.There are useful as well as harmful microorganisms.

Why microorganisms are called microorganisms ?

 Microorganisms can’t be  seen with unaided eye .To see microorganisms we need microscopes and in some cases magnifying glass that is why microorganisms are called microorganisms .

Microorganisms are categorized into four major groups .

Four groups in which microorganism are grouped a  Fungi,  Bacteria,  Algae and Protozoa.

Viruses

Viruses- Viruses consist of genetic materials (DNA or RNA) surrounded by a protective coat of protein.

 Viruses are microscopic and too small to be seen by the naked eye.

Viruses can't multiply on their own they reproduce only inside host organism,host may be plants animals or bacterium.

Viruses consist of genetic materials (DNA or RNA)

Virus is inactive when outside the host organism and become active inside host organisms.

Human diseases which are caused by viruses  include:

        Smallpox

        The common cold

        Measles

        Chickenpox

        Hepatitis

        Influenza

        Polio

        Rabies

        HIV (the virus that causes AIDS)

        SARS (Severe acute respiratory syndrome)

        Dengue

Diseases caused by bacteria

Cholera,

Typhoid Fever,

Tuberculosis(TB),

Leprosy (Hansen's Disease) ,

SYPHILIS ETC

Diseases caused by protozoa(Protozoans)

Malaria

Giardiasis

Trichomoniasis

Sleeping Sickness

Dysentery

Amoebiasis

Habitats of microorganisms

Microorganisms live in all place which you know .

Microorganisms live in extreme conditions where we can’t live ranging from hot springs to  ice cold climate and from marshy lands to deserts.

Microorganism even live in human body .

Some microorganisms are beneficial for us and some microorganism are harmful for us,plants and animals.

Benefits of Microorganisms to Humans

Uses of microorganisms

Friendly microorganisms

Friendly microorganisms are useful for us because they helps in cleaning environment by degrading dead and decay substances,microorganisms are used in increasing soil fertility.microorganism are used in making cake, bread and curd etc

Making curd and Bread

Lactobacillus Bacteria helps in the formation of curd from milk.

How milk is converted into curd ?

Lactobacillus denatures the structure of protein  casein  present in milk by producing Lactic acid it destroys the tertiary and quaternary structures of proteins  thus globular protein is converted into fibrous protein which gives thick textures to the milk due to the coagulation of proteins.

By this process milk is converted into curd.                 

Bacteria help in making cheese

Bacteria convert the natural sugars in milk (lactose) into lactic acid. Different flavor of the milk is due to the different types of bacteria used.

Bacteria also helps in making pickles and other food products.

Yeast (fungi –one of the group of microorganisms)

Uses of microorganisms,yeast in making cakes, breads, pastries in baking industry.

Bakers add yeast to dough ,yeast reproduces very fast and produces carbon dioxide during respiration.Bubles of the gas produced fills the dough  and increases its volume.

Commercial use of Microorganisms.

Commercially microorganisms are used for making wine ,alcohol and acetic acid(vinegar).

Wine and Alcohol are commercially produced by using Yeast (Fungi).

Microorganism yeast is grown on natural sugars present in crushed fruit juices,wheat,barley,rice etc and by the process of fermentation yeast convert sugars into alcohols.

Fermentation-the process of conversion of sugars into alcohol is known as fermentation.

Medicinal use of microorganisms

What is antibiotic?

Antibiotics -Antibiotics are a group of medicines that are used to treat

infections caused by bacteria and certain parasites.

Antibiotics are produced by the uses of bacteria.

Examples of antibiotics-Tetracycline,Streptomycin,erythromycin, Doripenem, Daptomycin, Clarithromycin, Penicillin G, Penicillin V etc

Uses of microorganisms in Increasing soil fertility

Bacteria (Biological nitrogen fixers)like blue green algae  fixes atmospheric nitrogen and convert it in other forms of nitrogen that is used by plants thus it enrich soils with nitrogen and increases the soil fertility.

Uses of microorganisms in Cleaning Environment

Microorganism converts dead and decaying  parts of plants and animals into manure  by decomposing them into simple substance.Thus the microorganism clean up the environment.

Harmful microorganisms

Microorganisms which are not good for us are called harmful microorganisms.

Microorganisms causes disease in animals ,human beings and plants therefore they are  also called pathogens.

Pathogens-Disease-causing microorganisms are called pathogens.

Diseases causing microorganisms in Humans

Pathogens presents everywhere. Pathogens transferred into our body from air, water and food or by direct contact with infected person or animal.

Malaria-Female anopheles mosquito carries parasite of  malaria.

Dengue virus-Female Aedes mosquito acts as carrier of Dengue virus.