CHAPTER 2 MICROORGANISMS FRIEND R AND FOE

Robert Köch (1876) discovered the bacterium (Bacillus anthracis) which causes anthrax disease

There are some insects and animals which act as carriers of disease causing 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. …

What is carriers of disease ? Read More »

Pathogen are transmitted by direct contact with an infected person or carried by an animal.Microbial diseases that can spread from an infected person to a healthy person through air, water, food or physicalcontact are called communicable diseases. Examples of such diseases cholera, common cold, chicken pox and tuberculosis.

Disease-causing micro – organisms are called Pathogens.The Nitrogen fixing cyanobacteria (blue green algae)

Some bacteria are able to fix nitrogen from the atmosphere to enrich soil with nitrogen and increase its fertility. These microbes are commonly called biological nitrogen fixers.

When a disease-carrying microbe enters our body, the body produces antibodies to fight the invader.

substance which is used to stimulate the production of antibodies, and provide immunity against one or a few diseases. vaccine works. Several diseases, including cholera, tuberculosis, smallpox and hepatitis can be prevented by vaccination.

. Edward Jenner discovered the vaccine for smallpox in 1798.

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 …

Discovery of an antibiotic Read More »

Medicines kill or stop the growth of the disease-causing microorganisms. Such medicines are called antibiotics. e.g Streptomycin, tetracycline and erythromycin etc.