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Transcript of Bacteria
live everywhere on
Earth. You can't
escape them, and for the most part,
you wouldn't want to Bacteria were first observed by Anton von Leeuwenhoek after he perfected the single lens microscope in 1676. He called them "animalcules." Bacteria are unicellular prokaryotes.
A prokaryote is an organism whose cells lack a nucleus and some other cell structures. The chromosomes are "loose" in the cell. Bacteria cells have one of three shapes - spherical, rod-shaped, or spiral. Over 3o% of the bacteria on your skin is Staphylococcus aureus. It is a common cause of infection. Streptococcus is a spherical-shaped bacteria that forms chains. It causes Strep throat. Escherichia coli (or E. coli) are rod-shaped bacteria that live in the intestines of warm-blooded animals. Most strains are helpful and help in digestion. They also prevent pathogenic bacteria from invading the gut. One strain of E.coli causes food poisoning. Borrelia burgdorferi are spiral-shaped bacteria that can cause Lyme disease. Most bacterial cells have a cell wall and a cell membrane.
They have cytoplasm and ribosomes, where proteins are produced. The DNA is string-like and in the shape of a circle. Not all bacteria can move, but many can by means of a structure called a flagellum.
A flagellum is a long, whiplike structure that helps a unicellular organism move.
A bacterial cell can have one flagellum or many flagella. They help the cell move by spinning like a propeller. Bacteria that cannot move depend on
wind, water, people, and animals to move
from place to place. These microscopic invaders are, of course, bacteria. There are more bacteria inside your mouth right now than there are people on Earth! Bacteria are divided into two Kingdoms - Archaebacteria and Eubacteria. The only difference between the two of them are chemical differences that allow Archaebacteria to exist in extreme conditions. Hot springs in Yellowsone National Park High salt areas like the Dead Sea Deep in the ocean in hydrothermal vents Eubacteria live virtually everywhere. There
are 100,000,000 to 1,000,000,000 bacterial cells in a spoonful of dirt. Most bacteria reproduce asexually.
Asexual reproduction is a reproductive process that involves only one parent and produces offspring that are identical to the parent. Binary fission is a type of asexual reproduction in which one cell divides to form two identical cells. Sexual reproduction involves two parents who divide their genetic material to produce a new organism.
Conjugation is a process in which a unicellular organism transfers some of its genetic material to another unicellular organism. During conjugation a thin, bridgelike tube forms between the two cells and the genetic material is passed from one to another. Conjugation does not result in offspring, but when the bacterium that received the DNA duplicates itself, the offspring will be different than the parent. BACTERIA As with all living organisms, bacteria need food. Some bacteria are autotrophs. They make their own food through the process of photosynthesis. Others make their own food using chemicals like ammonia in a process called chemosynthesis. Most bacteria are heterotrophs. The consume a variety of living organisms - leaves, meat, milk, etc. Like all organisms, bacteria must break down their food to release energy - respiration. Most bacteria need oxygen to do this just like most other organisms.
Bacteria called anaerobic bacteria not only do not need oxygen - they die in the presence of oxygen.
Many of the Archaebacteria are anaerobic. 99% of intestinal bacteria are anaerobic. Some bacteria have an incredible survival technique. When food or water runs out, or other conditions become unfavorable, these bacteria form endospores.
An endospore is a small, rounded, thick-walled, resting cell that forms inside a bacterial cell.
The endospore can survive freezing, extremely high temperatures, drought, salinity, and other harsh conditions. Scientists that study bacteria are called microbiologists. The Human Microbiome Project is similar to the Human Genome Project. It involves 200 scientists at 80 institutions who are sequencing the genetic material of bacteria taken from nearly 250 healthy people. Washington University in St. Louis is a part of this project.
They discovered more strains than they had ever imagined - as many as a thousand bacterial strains on each person. And each person's collection of microbes (the microbiome) was different from the next person's. Most people think of bacteria as harmful but actually, the great majority of bacteria help us to live healthier lives. The human gut is jam packed with bacteria. An adult carries 2 to 5 pounds of bacteria in their intestines! At least half of your stool is not undigested food - it's a microbial mass.
The bacteria in the human intestines help digest food and also keep pathogenic bacteria from multiplying and causing us to get sick. A pathogen is any
organism that causes disease. Bacteria are involved in the production of food and fuel. They help us clean up the environment by cleaning waste water, decomposing biodegradable products, and even cleaning up oil spills. You will be investigating some of these beneficial bacteria in a project. Many foods are produced with the help of bacteria. The natural gas we use to heat our homes and cook our food was produced by bacteria. The methane gas was produced by anaerobic Archaebacteria millions of years ago as a by-product of their respiration. Many species of heterotrophic eubacteria that live in the soil are decomposers. They break down dead organisms into chemicals that are reused by living organisms. A decomposer is an organism
that break down large chemicals
in dead organisms into small chemicals that can be used by living organisms. There are bacteria that actually "eat" oil. Can they be used to clean up oil spills? An infectious disease is a disease that can pass from one organism to another. Both bacteria and viruses can cause an infectious disease.
Infectious diseases can be spread by direct or indirect contact. Infectious diseases can also be contracted from an animal bite, such as a dog, tick, or mosquito. Harmful bacteria can be ingested when we eat contaminated food. Many bacteria diseases can be cured with medications known as antibiotics.
An antibiotic is a chemical that can kill bacteria without harming a person's own cells.
The first antibiotic was discovered serendipitously by Alexander Fleming in 1928. http://science.discovery.com/tv-shows/greatest-discoveries/videos/100-greatest-discoveries-the-discovery-of-penicillin.htm In 1939, Ernst Chain and Howard Florey continued Fleming's work. They developed a technique to isolate the chemical and used it to treat soldiers that in World War II.
Penicillin was first produced for civilian use in 1945 in Australia
Fleming, Chain, and Florey shared the 1945 Nobel prize for their work. Penicillin works by weakening the cell walls of certain bacteria until the cells burst.Penicillin and its derivatives is still the most widely used antibiotic in the world.