Science Year 5: LEARNING TIME

TOPIC 1

WHAT IS MICROORGANISM

The microorganism term is used instead of microbes; they are very small organisms size belonging to various groups: Bacteria, Fungi,Protozoa, one can add Viruses, characterized by their noncellular structure. Microorganisms were observed for the first time in 1674 by Van Leeuwenhoek but they are only identified 200 years later.
Although those organisms are incredibly small (their size ranges from 0.03 µm for the virus of the foot-and-mouth disease to 300 µm for Paramecium), they play a significant role to keep the planet running. Indeed, they carry out 90% of the biochemical reactions produced on earth, without them the life on earth would be destroyed.
The micro-organisms are probably the first alive beings appeared on ground, they would be thus the common ancestors of all the living being. Although microorganisms appeared 3.8 billion years ago, they are observed by Pasteur and koch through their microscope way after their apparition. Pasteur delivered the fatal blow to the doctrine of spontaneous generation thanks to his examination and Koch discovered revealed the existence of bacilla at the origin of tuberculosis. Those discoveries changed radically the perception of the human beings on the world

MICROORGANISM

MICROORGANISM - HABITATS AND ECOLOGY

Microorganisms are found everywhere in nature. Even in hostile environments, like the poles, deserts, geysers, rocks, and the deep sea, some types of microorganisms have adapted to the extreme conditions and sustained colonies; these organisms are known as extremophiles. Some extremophiles have been known to survive for a prolonged time in a vacuum, and some can be unusually resistant to radiation. Microorganisms are used in brewing, baking, biotechnology, recycling of other organisms' remains and waste products, and many other processes. They can also be harmful as pathogens when, as parasites, they cause infections.

Microorganisms have an important place in all ecosystems and in most higher-order multicellular organisms. For mankind they are important because they participate in the earth's element cycles (such as the Carbon cycle), and because of their use in the creation of certain types of food, medicines and biological weapons.

TYPES OF MICRORGANISM

Yeast

Yeasts constitute a group of single-celled (unicellular) fungi, a few species of which are commonly used to leaven bread, ferment alcoholic beverages, and even drive experimental fuel cells.

Protozoa

Protozoa are single-celled eukaryote (organisms whose cells have nuclei) that commonly show characteristics usually associated with animals, most notably mobility and hetero trophy. Protozoa have traditionally been divided on the basis of locomotion. Most protozoans’ are too small to be seen with the naked eye - most are around 0.01-0.05 mm, although forms up to 0.5 mm are still fairly common - but can easily be found under a microscope.

PROTOZOA