Microorganisms

1. Microorganisms

2. Whatare
Microorganisms?
¤A microorganism is a microscopic
organism that comprises either a
single cell, or multicellular organisms.
¤The study of microorganisms is called
microbiology, a subject that began
with Anton van Leeuwenhoek’s
discovery of microorganisms in 1675,
using a microscope of his own design.

3. Types of Microorganisms
🞅Bacteria
🞅Fungi
🞅Protozoa
🞅Algae
🞅Virus

4. Viruses
Viruses are too small to be seen with the naked
eye. They can’t multiply on their own, so they have to
invade a ‘host’ cell and take over its machinery in
order to be able to make more virus particles.
Viruses consist of genetic materials (DNA or
RNA) surrounded by a protective coat of protein.
They are capable of latching onto cells and getting
inside them.
The cells of the mucous membrane, such as those
lining the respiratory passage that we breathe
through, are particularly open to virus attacks
because they are not covered by protective skin.

5. Fungi
Fungi are like plants that are not ‘green'; they
do not have the photosynthetic material
chlorophyll. They have no roots, stems or leaves
but grow as masses of protoplasm in dead and
living organic matter.
 There are about 1,00,000 different fungi.
Some like the yeasts are single cells but most
fungi grow as branching tubes of protoplasm
called hyphae. Fungi also contain chitin which is
also found in animal cells. A single organism is
called fungus.

6. Bacteria
Bacteria are organisms made up of just one
cell. They are capable of multiplying themselves,
as they have the power to divide. Their shapes
may vary, and doctors use these characters to
separate them into groups.
Bacteria are omnipresent. Most are harmless,
even useful.
But some cause diseases, either because they
end up in wrong place or simply because they are
‘designed’ to invade us.

7. Protozoa
Protozoa are small (but not simple) organisms.
They are single-celled heterotrophic
eukaryotes, which eat bacteria and other food
sources.
There are about 30,000 protozoan species.
They are found only in moist or aquatic
habitats.
Many protozoan species are symbionts, some
are parasites, and some are predators of soil
bacteria and algae.

8. Algae
Algae are a type of living thing that usually
live in really wet environments, like the oceans.
They are a little bit like plants.
They too, carry out photosynthesis, just like
the plants do!
The difference between algae and plants, is
that plants have a lot of more distinct parts, like
roots, stem and leaves.

9. Disease causing microorganisms
in Humans
o Disease causing microorganisms enter our body through
air, water, food, contact or insects. These microorganisms
are called pathogens.
o Diseases which can spread from an infected person to a
healthy person are called communicable diseases.
o Eg :- cholera, common cold, chicken pox, tuberculosis etc.
o Some insects and animals act as carriers of disease
causing microbes.
o Eg :- House fly, Female anopheles mosquito (malaria),
Female aedes mosquito (dengue fever) etc.

10. Disease causing microorganisms
in plants
Microorganisms cause diseases in plants like rice, wheat,
potato, sugarcane, apple, orange etc. These diseases reduce
crop yield. They can be controlled by using chemicals which
kill the microbes.

11. Thank
You