Microorganisms

Organisms which can only be seen through a microscope are known as Microorganisms or Microbes. Microbes were the first life forms/organisms which lived on the planet Earth.
INTRODUCING MICROBES :

Bacteria
Protozoa
Fungi
Algae
Virus
Archaea

BACTERIA

Bacteria are single-celled microbes. They are found almost everywhere on the Earth, and are absolutely necessary to the ecosystem of the planet.
Some species of bacteria can survive under extreme conditions.
The human body is full of bacteria, and contain more bacterial cells than human cells.

PROBIOTICS : The good bacteria

Probiotics helps to keep our gut healthy.
They fight off the foreign invaders (microbes).
Are considered as functional foods.

HARMFUL BACTERIA

Most of the bacteria are harmless but however there are several species of bacteria which are pathogenic and cause harm to our body and cause diseases such as - (Examples)

Vibrio Cholerae - Cholera
Mycobacterium Tuberculosis - Tuberculosis
Streptococcus Pnemoniae - Pnemonia
Clostridium Tetani - Tetanus
Yersinia Pestis - Bubonic Plague (also known as the black death)

PROTOZOA

Protozoa are unicellular, eukaryotic, heterotrophic, aquatic organisms. They are either free-living or parasitic that feed on organic matter such as other microbes or organic tissues and debris.
They come in different shapes and sizes ranging from an amoeba which can change its shape, to a paramecium which has a fixed shape and a complex structure.
Some protozoans are parasitic, which means they live in plants, animals and humans, where they cause diseases.
Some protozoans are saprophytic that help in cleaning the environment.
Most cause no harm but the best-known protozoal menace is Plasmodium, the parasite that causes malaria. This disease leads to about 800,000 deaths each year worldwide.

CHARACTERISTICS OF LOCOMOTION IN PROTOZOA :

Cilia - tiny hair like structures that cover the outside of the microbe.
Flagella - long thread-like structures that extend from the cell surface. The flagella move in a whip-like motion that produces waves that propel the microbe around.
Amoebiod Movement - the organism moves by sending out pseudopodia, temporary projections that fill with cytoplasm that flows from the body of the cell.

Few Protozoa Examples

Amoeba
Paramecium
Plasmodium
Euglena

FUNGI

Fungi are microorganisms that are mostly multicellular, there are unicellular fungi as well.
They are found in any habitat but mostsly live on land, mainly on soil or on plant material rather that sea or fresh water bodies.
They are mainly heterotrophs. But some fungi are saprotrophs.
The saprophytic fungi feed on dead and decaying matter. Which then break down this dead and decaying matter into simpler substances that can be used up by plants.
Examples of fungi - yeasts, rusts, stinkhorns, puffballs, truffles, molds, mildews and mushrooms.

YEAST :

Yeasts have two main uses in food production: baking and making alcoholic beverages.
Yeast breads are made with yeast. Combining warm water and sugar with yeast causes the yeast to multiply and release carbon dioxide, which, when mixed with dry ingredients, creates a soft loaf of bread.
Yeast keeps your digestive system healthy and in balance.

DISEASES/INFECTIONS

A very small number of fungi cause diseases in animals. In humans, these include, skin infections/diseases.
Examples of fungal infections in humans - Ringworm, Athlete's foot, Thrush, Aspergillosis.

ALGAE

Algae are a diverse group of aquatic organisms that have the ability to conduct photosynthesis.
They can exist in single cell such as the chlamydomonas or can exist as multicellular like the Rhodymenia (red seaweed).
Most are aquatic and autotrophic which lack many of the similar cell and tissue types, such as stomata, xylem and phloem that are found in common land plants.

TYPES OF ALGAE
There are many types of algae, but here are the important types of algae -

RED ALGAE (Rhodophyta):

Red algae are the oldest group of eukaryotic algae. They are mostly found in marine and freshwater.
This type of algae is red in colour due to the presence of pigment called phycoerythrin. This pigment reflects red light and absorbs blue light and thus gives a reddish appearence to the algae.
They also contain chlorophyll which help them preparing their own food by the process of photosynthesis.
Red algae are used to produce agar that is used as a food additive.
Few examples of red algae - Airish moss, Naver (Nori), Coralline algae.

2. GREEN ALGAE :

Green algae mostly occur in fresh water and are usually attached to submereged rocks and wood or as scum on stagnant water. But there are also terrestrial species.
The photosynthetic pigments are in the same propotions as those in other higher land plants.
The green algae are an important food source of aquatic organisms.
They are also a vital source of atmospheric oxygen becuase of their photosynthetic activity.
Few examples of green algae - Chlamydomonas, Hydrodictyon, Spirogyra, Caulerpa.

VIRUS

Viruses are the smallest among all other microbes.
They consist of a genetic material (DNA or RNA) enclosed within a protein coat.
They lack cellular framework and need a host cell to reproduce or multiply.
Outside the host cell, viruses cannot function.
Thus they say that viruses are dead outside the host but alive inside the host.

THE JOURNEY OF THE VIRUS :

Once the virus enters inside the host cell, it starts to overpower/control the cell.
Uses the cell machinery to multiply itself.
Due to this, the cell bursts open and the surrounding cells are infected.
The virus is now spread all over the body.

Examples of virus -

Smallpox
Chickenpox
Measles
Covid-19

ARCHAEA

All arganisms such as humans, trees, animals, microbes etc. all point to one ancestor, ARCHAEA (Microorganism).
Archaea are prokaryotic in nature.
3500 million years ago, when the conditions on the planet Earth were very harsh, Archaea were one of the first life forms which survived these extreme conditions.

PROTECTION FROM INFECTIOUS AGENTS

Vaccines

Vaccine is made up of a weakened pathogen and is used to develop immunity against that pathogen.
Stimulation of our immune system by a vaccine to recognise the pathogen and protect us from future infections is known as Immunisation.

EDWARD JENNER

The smallpox vaccine was discovered by Edward Jenner (Scientist). He is known as the father of vaccine.
Edward Jenner observed the milk maids who are exposed to the cowpox virus were not infected by smallpox. On May 14 1796, Jenner took fluid of a cowpox blister and tested it on a small 8 year old boy suffering from smallpox. This boy, after being tested, was cured.
This is how Edward Jenner discovered the vaccine for smallpox and it was the first successful vaccine to be developed.

ANTIBIOTICS

An antibiotic is a type of antimicrobial substance that work against bacteria. They either kill bacteria or stop them from multiplying.

They interfere with bacteria's ability to repair.
They stop the bacteria's ability to make/grow new cells.
Weakens bacteria's cellwall until it bursts open.

ALEXANDER FLEMING

The first antibiotic was discovered accidentally by
Alexander Fleming in the year 1928.
He discovered the first antibiotic - penicillin, which is extracted from a mould Penicillium. Penicillin inhabits the growth of bacteria by blocking the biochemical pathway responsible for the synthesis of the cellwall.

Examples of antibiotics -

Streptomycin
Tetracycline
Erythromycin

ANTIBIOTICS can't distinguish between good bacteria and bad bacteria,
THEREFORE IT IS IMPORTANT TO TAKE ANTIBIOTICS IN THE CORRECT DOSAGE.

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