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Science project 6F Sara

Sara A

on 10 December 2012

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Transcript of Microorganisms

Microorganism 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. How big are they ? Microorganisms are incredibly small their size ranges from 0.03 pm for Paramecium. When did they appear ? The micro-organisms are probably the first alive beings appeared on ground, they would be thus the common ancestors of all the living being.Microorganisms appeared 3.8 billion years ago, they are observed by Pasteur and koch through their microscope way after their apparition. What are the different types of Microorganisms? Bacteria Bacteria are the simplest of creatures that are considered alive. Bacteria are everywhere. They are very simple cells that fall under the heading prokaryotic. That word means they do not have an organized nucleus. Bacteria are small single cells whose whole purpose in life is to replicate. They are a type of microorganisms. Viruses A virus is very small - much smaller than a cell. It can't survive for long on its own, but only inside the cells of living creatures - bacteria, plants or animals. A virus is just a few molecules of genetic material, nucleic acid (DNA or RNA), wrapped up in a layer of protein molecules to protect it. Some viruses are shaped like spirals, others like soccer balls. A few big viruses combine both forms, so they have a soccer ball shape with a spiral tail. They are a type of microorganisms. Fungus The Kingdom Fungi includes some of the most important organisms, both in terms of their ecological and economic roles. By breaking down dead organic material, they continue the cycle of nutrients through ecosystems. They are also another type of microorganisms. Algea Algae, diverse group of simple, plantlike organisms. Like plants, most algae use the energy of sunlight to make their own food, a process called photosynthesis. However, algae lack the roots, leaves, and other structures typical of true plants. Algae are the most important photosynthesizing organisms on Earth they are microorganisms. Protozoa Protozoan are simple organisms, or living things. They belong to a group of organisms called protists, which are neither plants nor animals. Most protozoans are so tiny that they can be seen only with a microscope and are called microorganisms. Now how about a video... That was annoying but lets move on ... For thousands of years, people had no concept or knowledge of organisms invisible to the naked eye. In fact, it is only within the last several hundred years that magnification systems (microscopes) were developed that enabled scientists to observe microorganisms. In 1673 Antoni van Leeuwenhoek was the first to observe and study microorganisms, using single lenses that magnified objects fifty to three hundred times. Microorganisms are present in high populations in soil, and in varying numbers in the air we breathe, the water we drink, and the food we eat; they are on our skin and in our noses, throats, mouths, intestinal tracts, and other bodily cavities. They are everywhere in our environment. Microorganisms Causing Food Poisoning Three species of bacteria cause food poisoning via preformed toxin: Clostridium botulinum, Staphylococcus aureus, and Bacillus cereus. Clostridium botulinum is a bacterium that grows in the absence of oxygen and produces one of the most toxic, deadly chemicals known to humans. It was first isolated from sausages, but later was responsible for death in persons consuming home-canned vegetables. A second serious type of food poisoning is caused by the ingestion of staphylococcal toxin produced by Staphylococcus aureus in foods such as cream puffs, mayonnaise, ice cream, or other nutritious foods that become infected with staphylococci, often carried in the nasal secretions of food handlers. Bacillus cereus also produces a food-poisoning toxin. Steamed rice held overnight at room temperature has been a typical food causing Bacillus cereus poisoning. There are two toxins involved—one causing nausea and vomiting, the other causing diarrhea. The toxins are not inactivated by boiling. Microorganisms as Food Blue-green algae of the genus Spirulina have been harvested from ponds and eaten for centuriesby the ancient Aztecs in Mexico and Africans in the region of Lake Chad. Mushrooms, the fruiting bodies of microorganisms that live on decaying lignocellulosic compounds in soil, are highly prized as food by nearly all human societies, as well as by many animals, including insects. As world population rises in the twenty-first century, microbes may be used to a much greater extent to feed mankind, or at least feed animals that, in turn, will yield meat for the human diet. Humans, plants, and animals have been intimately involved with microorganisms ever since they evolved. While some of the microorganisms cause serious diseases, there are also many that provide foods and feeds and are beneficial to other life on earth. GALLERY
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