Microorganisms Lesson 5

Microorganisms What is a Microorganism? Microorganisms are tiny creatures, too small to be seen with just our eyes. Microorganisms provide larger organisms with some of the food and oxygen they need to survive.

Studying Microscopic Organisms A microscope is an instrument that produces an enlarged image of an object. Anton van Leeuwenhoek: Dutch merchant used a microscope to study organisms in the 1600’s. A compound microscope uses two or more lenses and a light source to magnify objects as much as 2,000 times.

Studying Microscopic Organisms An electron microscope uses a beam of electrons rather than a light source to magnify samples. Electron microscopes cannot be used on living samples, because the stream of electrons and the preparation process would kill them.

How are microorganisms beneficial? Microorganisms are decomposers. A decomposer is an organism that breaks down dead materials into simpler substances. Decomposers recycle substances that would otherwise remain useless.

Food Production Yogurt, sour cream and cottage cheese are produced by bacteria. Bacteria also helps improve the flavor of cocoa, tea and coffee. Even pickles and sauerkraut are prepared with the help of bacteria.

How are microorganisms harmful? Some microorganisms are parasitic, meaning they cause damage to plants and animals. Some microorganisms make you feel sick, while others can be deadly.

Harmful Microorganisms Infectious Disease: Some cause disease by destroying cells directly. (Strep Throat, or pneumonia) Bacteria cause disease by producing poisonous substance toxins (poison). Bacteria also live in uncooked meats, raw eggs, and other foods. E. coli and Salmonella are two of the most well-known. Fever and sore throat are two examples of symptoms.

Harmful Fungi Microorganisms can also harm plant life. These are considered parasites because they live on a host organism causing harm to it. In the nineteenth century, a fungus spread throughout Ireland and destroyed large amounts of the potato crop, causing thousands to starve. It was known as the Irish Potato Famine.

Harmful Fungi Athlete’s foot is another example of a disease caused by harmful microscopic fungus. It is found in damp places and lives on skin. The symptoms include itching and blisters between a person’s toes.

Protists Parasitic protists can also cause health problems in animal species. Malaria is an example of a parasitic protist. The protist is spread by the mosquito and then reproduces inside red blood cells, destroying the blood cell. When the blood cells are destroyed new parasites are released into the animal. Results, severely high fever and the chills.

How do we protect ourselves? Antibiotics are used to treat bacterial infections. Antibiotics stop the growth of bacteria. Antibiotics are produced from bacteria and molds, and are artificially produced in labs. Each antibiotic only works on certain types of bacteria. For each new bacterial infection, new antibiotics must be developed!

Food Safety Pasteurization is used to ensure the safety of our food. Heating milk and other liquids to a high temperature kills the bacteria without altering the liquid. Cooking also destroys harmful bacteria in food, by destroying the bacteria cells. The government also has food inspectors to ensure the safety of foods.