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Transcript
Chapter 7 Bacteria What are bacteria? • Bacteria are microscopic, living cells. – live almost everywhere, even extreme environments – sphere-shaped, rod-shaped, spiral-shaped • smaller than plant or animal cells • prokaryotic-no membrane-bound internal structures What are bacteria? – some have a capsule around the cell wall while others have an outer slime layer – many have whiplike tails called flagella – most reproduce by fission What are bacteria? – can be producers or consumers • most are aerobes • some are anaerobes What are bacteria? • Bacteria are classified into two kingdoms. – Eubacteria larger of the two bacteria kingdoms • consumer eubacteria are grouped by cell wall thickness • cyanobacteria produce their own food and are commonly called blue-green bacteria • cyanobacteria provide food and oxygen for aquatic life – bloom- may be harmful What are bacteria? • Bacteria are classified into two kingdoms. – Archaebacteria • kingdom bacteria are often found in extreme locations and divided into groups based on where they live or how they get energy – some live in salty, acidic, or very hot environments – one anaerobic group produces methane gas Bacteria in Your Life • Most bacteria are helpful rather than harmful – necessary for human health • many aid digestion and some produce vitamins • some produce antibiotics Bacteria in Your Life • Bacteria help keep nature in balance – bacterial saprophytes use dead organisms as food and energy sources – nitrogen-fixing bacteria in the soil and plant roots change nitrogen from the air to a form that plants and animals can use Bacteria in Your Life • Bacteria can be used to clean up the environmental pollution through bioremediation – some bacteria break waste down into harmless compounds – certain bacteria can eat pollutants Bacteria in Your Life • Many foods are made using bacteria – used in dairy products – sauerkraut and pickles are also among foods made with bacterial help Bacteria in Your Life • Bacteria are used in industry – bioreactors- large, carefully controlled containers used to make medicines and many other products – methane-producing bacteria can digest waste and provide a source of fuel Bacteria in Your Life • Bacteria that cause disease are called bacterial pathogens – toxins are made by some bacterial pathogens – some form thick walled structures called endospores when environmental conditions are unfavorable Bacteria in Your Life – pasteurization- process of limited heating, can kill most harmful bacteria in food – vaccines can prevent some bacterial infections • made from damaged or dead bacterial cells • enable white blood cells in the body to recognize a particular type of bacteria and attack it if it appears at a later time