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Bacteria. Glencoe Science Chapter 3. Vocab. Words. flagella – whip like tails of many bacteria that help them move around in moist conditions.
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Bacteria Glencoe Science Chapter 3
Vocab. Words flagella – whip like tails of many bacteria that help them move around in moist conditions. fission – simplest form of asexual reproduction in which two new cells are produced with genetic material identical to each other and identical to the previous cell. aerobe – any organism that uses oxygen for respiration. anaerobe – any organism that is able to live without oxygen. antibiotic – chemical produced by some bacteria that is used to limit the growth of other bacteria. saprophyte – organism that feeds on dead or decaying tissues of other organisms.
More Vocab. Words nitrogen-fixing bacteria – bacteria that convert nitrogen in the air into forms that can be used by plants and animals. pathogen – disease-producing organism. toxin – poisonous substance produced by some pathogens. endospore – thick-walled, protective structure produced by a pathogen when conditions are unfavorable for survival. vaccine – preparation made from killed bacteria or damaged particles from bacterial cell walls that can prevent some bacterial diseases.
What are bacteria? Section 1
Who discovered bacteria? Antonie van Leewenhoek observed tiny scrapings from his teeth in the later half of the seventeenth century. Although he didn’t know it at the time, the tiny swimming organisms that he saw were bacteria. A century later, bacteria were proven to be living cells that carry on the processes of life.
Where are bacteria? Bacteria are almost everywhere. They are in the air, the foods that you eat and drink, the things you touch, deep underground, at great ocean depths, in the soil, on your arm, hot springs, hydrothermal vents, and in water.
The Shapes of Bacteria Bacteria usually come in three shapes-
Cocci Shaped – like a sphere Pronounced – KAH ki Singular – coccus
Bacilli Shaped – like a rod Pronounced – buh SIH li Singular – bacillus
Spirilla Shaped – like a spiral Pronounced – spi RIH luh Singular – spirillum
Structure of Bacterial Cells Bacteria are one-celled organisms that occur alone or in chain groups. A typical bacterial cell contains cytoplasm surrounded by a cell membrane and a cell wall. Bacterial cells are classified as prokaryotic because they do not contain organelles, like a nucleus. Most of the genetic material of a bacterial cell is in its one circular chromosome. Many bacteria also have a plasmid, which is a small circular piece of DNA. Ribosomes are found in a bacterial cell’s cytoplasm.
Bacterial Cell Cell Membrane Flagellum Chromosome Ribosome Cell Wall Cytoplasm Gelatin like capsule
Special Features that Some Bacterial Cells Have: A thick gelatin like capsule (This protects the cell and allows it to stick to surfaces.) Slime layer (This allows it to stick to surfaces and reduces water loss.) Flagella (These are whip like tails that help them move.)
Reproduction Bacteria usually reproduce by fission, which is a process that produces two new cells with genetic material identical to each other and the original cell. (Fission is the simplest form of asexual reproduction.) However, sometimes two bacteria line up beside each other and exchange material through a fine tube. This results in cells with different combinations of genetic material than they had before the exchange, allowing the bacteria to acquire variations that help them survive.
Bacteria Obtain Their Food In a Variety of Ways: Bacteria that contain chlorophyll or other pigments make their own food using energy from the Sun. (These are called producers, because they can make their own food.) Other bacteria use energy from chemical reactions to make food. (These are also called producers.) Some bacteria break down dead organisms to obtain energy. (These are called consumers.) Other bacteria live as parasites of living organisms and get energy from their host. (These are called consumers.) Most bacteria are consumers!
Aerobe vs. Anaerobe Most organisms use oxygen when they break down food for respiration. (These organisms are called aerobe.) An organism that is adapted to live without oxygen is called anaerobe. Some anaerobic bacteria can live where oxygen is present, others can’t.
Bacteria’s Kingdoms Bacteria are classified into two kingdoms – Eubacteria and Archaebacteria. Eubacteria is the larger kingdom.
Eubacteria • Characteristics Used to Group Eubacteria: • Cell shape • Cell structure • How they get food • What food they eat • How they move • What wastes they produce • Whether they are anaerobe or aerobe
Cyanobacteria Cyanobacteria is a group of eubacteria. Cyanobacteria make their own food using carbon dioxide, water, and energy from sunlight. Cyanobacteria produce oxygen as a waste. Cyanobacteria contain chlorophyll and another pigment that is blue. This gives them their common name: blue-green bacteria. (However, some cyanobacteria are yellow, black, or red.) Some cyanobacteria live together in long chains or filaments. Many cyanobacteria are covered with a gelatin like substance. This enables them to live in colonies. When the population grows large enough, a bloom is produced. This looks like a mat of bubbly green slime on the surface of the water.
Archaebacteria Kingdom Archaebacteria contains bacteria that can be found in very extreme conditions. Archaebacteria are divided into groups based on where they live, or how they get energy. Archaebacteria can live in salty, acidic, and hot environments. Methane producers are anaerobic bacteria (in the Kingdom Archaebacteria) that use carbon dioxide for energy and produce methane gas as a waste. Sometimes this gas bubbles up out of swamps and marshes. They can be used to break down waste material from sewage water.
Bacteria in Your Life Section 2
Beneficial Bacteria Few bacteria cause illness. Some bacteria produce antibiotics that limit the growth of other bacteria. Many diseases in animals (including humans) can be treated with antibiotics. Saprophytes help maintain nature’s balance – they use dead organisms as food and energy sources. Without them, there would be layers of dead material all over Earth, deeper than you are tall. Saprophytic bacteria help recycle nutrients by making the nutrients available for other organisms to use.
Another Kind of Beneficial Bacteria Nitrogen-fixing bacteria change nitrogen in the air into forms plants and animals can use. This is important because plants and animals must take in nitrogen to make needed proteins and nucleic acids, but they can not use nitrogen directly. Some plants (such as peanuts and peas) develop structures called nodules that contain nitrogen-fixing bacteria. Nitrogen-fixing bacteria save U.S. farmers millions of dollars each year in fertilizer.
Steps in Nitrogen Fixation (the process where bacteria convert nitrogen in the air into usable forms) Nitrogen-fixing bacteria enter a plant through thin-walled cells on a root’s outer surface (root hairs). The bacteria enlarge and cause the plant to produce a sort of tube called an infection thread. The bacteria move through this thread to reach cells deeper inside the root. The bacteria divide in the root cells, causing nodules to form on the roots.
Bacteria and Food Bacteria is used in making many foods. For example: yogurt, cheese, buttermilk, sauerkraut, vinegar, pickles, olives, soy sauce.
Bacteria in Industries Many industries rely on bacteria to make many products. Bacteria are grown in large containers called bioreactors.
Harmful Bacteria • Some bacteria are known as pathogens – which are organisms that cause disease. • Bacterial pathogens can enter your body in several different ways: • Enter through a cut in the skin • Be inhaled • And more!
Harmful Bacteria Once inside your body, bacterial pathogens multiply, damage normal cells, and cause illness and disease. Some bacterial pathogens produce poisonous substances known as toxins. Botulism (a type of food poisoning) is caused by a toxin-producing bacterium.
Endospores When growing conditions are unfavorable for their survival, some bacterial pathogens can produce thick-walled structures called endospores. Endospores can exist for hundreds of years before they resume growth.
Pasteurization Pasteurization is a process of heating food to a temperature that kills most harmful bacteria but causes little change to the taste of the food. (You may notice that it says “pasteurized” on your milk at home, or on many other dairy products.)
Killing Disease Bacterial diseases in humans and animals are usually treated effectively with antibiotics (like penicillin, an antibiotic that prevents bacteria from making cell walls.) Vaccines are made from killed bacteria or damaged particles taken from bacterial cell walls. They prevent some diseases.
Questions Are you ready???
Section 1 How do bacteria use flagella? Why are cyanobacteria classified as producers? What are the characteristics common to all bacteria? How do aerobic and anaerobic organisms differ? How do most bacteria reproduce? Who is given credit for first discovering bacteria?
Section 2 What is a saprophyte? What waste gas produced by some bacteria can be used as a fuel? Why are saprophytic bacteria helpful and necessary? Why are nitrogen-fixing bacteria important? List three uses of bacteria in food production and industry. How do some bacteria cause disease?
Checking Concepts What is a way of cleaning up an ecosystem using bacteria to break down harmful compounds? What do bacterial cells contain? What pigment do cyanobacteria need to make food? True or false: Most bacteria are beneficial. What is the name for rod-shaped bacteria? What structure allows bacteria to stick to surfaces? What organisms can grow as blooms in ponds?
Cont. What are “recyclers” in the environment? (Hint: Without them, there would be a layer of dead material covering the Earth, deeper than you are tall.) What is an example of a disease caused by a pathogenic bacterium? What organisms do not need oxygen to survive?
Get ready for the next section – Protists and Fungi! That’s all for now!