MindMap Gallery Class 8 Chapter 2 Microorganisms
A microorganism, or microbe, is a microscopic organism, which may exist in its single-celled form or a colony of cells. 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.
Edited at 2023-10-02 06:52:02Microorganisms
Definition
Organisms not visible to naked eyes, Only visible under microscope.
Places to be found
Everywhere
Either live on host's body or Live freely
Types
Alga/Algae
They have chlorophyll
They can be unicellular or multicellular
Eg-> Chlamydomonas, Spirogyra
Bacterium/Bacteria
They don't have organelles
They are unicellular
Eg->Vibriocholerae, Lactobacillus, Cyanobacteria
Fungi/Fungus
They are Saprophytes
They can be unicellular or multicellular
Eg-> Bread mould, Aspergillus, Penicillium
Protozoan/Protozoa
They are parasites
They are unicellular
Eg-> Amoeba, Paramecium, Plasmodium
Harmful Microorganisms
Pathogens are disease-causing microorganisms
In humans
In plants
In animals
Some microorganisms spoil food, clothing and leather
Food Poisoning
Advantages of Microorganisms
Making of Curd, Bread
Curd is made by Lactobacillus which promotes conversion of milk into curd
Bacteria and Yeast are used for fermentation in rice idlis and dosa batter as when they respire, they release CO2 which bubbles the dough and increase its volume
Yeast is used in baking industry to make breads, pastries and cakes fluffy and soft
Commericial Usage
Microorganisms are used for making alcohol, wine and acetic acid or vinegar
Yeast is used for alcohol and wine production as if we feed them on natural sugars, they do fermentation(process of conversion of sugar into alcohol)
Medicinal Usage
Antibiotics are medicines obtained from microorganisms which stop the growth of disease-causing microorganisms in our body
Eg-> Streptomycin, Tetracycline, Erythromycin, Azithromycin
They are mixed in fodder of livestock and poultry to check microbial infection in animals
• Antibiotics should be taken by prescription of qualified doctor • We should complete the course of medicines given by doctor • If taken in no need or wrong doses, it will be less effective when needed • Unnecessary doses may kill beneficial bacteria in body • They are not effective against viral diseases
Vaccine
Antibodies (Immunoglobulin Protiens or Clycoprotiens) are produced when invader enters the body
Antibodies learn how to fight a particular microorganisms by experiencing it
Vaccines are dead/weakened microorganisms which teach body how to release suitable antibodies for a particular disease
Children are given vaccines in different ages to prevent diseases and are encouraged to be given in programmes like Pulse Polio Programme
Increasing the soil fertility
Some Microorganisms convert atmospheric nitrogen into soluble nitrogen and increase soil fertility for plants
Cleaning the environment
Animal and plant wastes are decomposed by microorganisms
They also release the nutrients back into the soil
Facts
Louis Pasteur discovered Fermentation in 1857
In 1929, Alexander Fleming was working on a culture of disease causing bacteria. Suddenly he found the spores of a little green mould in one of his culture plates. He observed that the presence of mould prevented the growth of bacteria. In fact, it also killed many of these bacteria. From this the mould penicillin was prepared.
Edward Jenner discovered the first vaccine of smallpox in 1798
Robert Köch (1876) discovered the bacterium (Bacillus anthracis) which causes anthrax disease
Food Preservation
Spoiled food emits bad smell and changed colour and has a bad taste while also being dangerous to us so we should preserve food
Chemical Method
Salt or acid preservatives prevent attack
Eg-> Sodium Metabisulphate, Sodium Benzoate in Jams and Squashes
Sugar
Sugar reduces moisture which prevents attacks
Eg-> Sugar in Jams, Jellies. Squashes
Common Salt
It is used since ancient times for prevention of bacteria
Eg-> Sodium Chloride in Amla, Raw mangoes, Tamarind
Oil and Vinegar
Bacteria cannot live in such environment
Eg-> Oil and Vinegar in Pickles, Vegetables, Fish, Meat
Heat and Cold Treatments
Low and high temperature can kill microorganisms
Pasteurisation is the process of heating milk to 70 degrees for 15 to 30 seconds and suddenly chilling and storing
Storage and Packing
Frutis and vegetables can be stored in sealed air tight packs to prevent attack
Nitrogen Fixation
Nitrogen is essential for plants to make protiens, amino acid etc. which are building blocks of life but plants can't take it directly from atmosphere so they have to be synthesized by bacteria first.
1st. Nitrogen Fixation-> The Atmospheric Nitrogen is turned into soluble nitrogen by either nitrogen fixing bacteria or energy of a lightning.
2nd. Nitrification-> The soluble nitrogen is released into the soil.
3rd. Assimilation-> The soluble nitrogen is taken up by the plants for utilisation.
4th. Ammonification-> When animals take up the plants and later on die, their dead body releases nitrogen back into the soil.
5th. Denitrification-> When the nitrogen returns back in soil, denitrifying bacteria turn it back into atmospheric nitrogen and release it.