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Transcript
Ahh! Germs – Everywhere! Germ = microorganisms (microbes) *tiny life forms that multiply Examples: Viruses, Fungi, Bacteria 1 What are bacteria/Why should I care? • You may have over a billion bacteria on the inside and outside of your body right now • Maybe half a million under each fingernail 2 BACTERIA Bacteria – unicellular, prokaryotes Bacteria like a warm, dark, and moist environment They are found almost everywhere: -water -air -soil -food -skin -inside the body -on most objects 3 7 Major Structures of a Bacteria Cell •Capsule •Cell wall •Ribosomes •Chromosome (nucleoid) •Flagella •Pilli •Cytoplasm 4 7 Major Structures of a Bacteria Cell Capsule keeps the cell from drying out and helps it stick to food or other cells More likely to cause disease 5 7 Major Structures of a Bacteria Cell Flagellum a whip-like tail that some bacteria have for locomotion 6 7 Major Structures of a Bacteria Cell Pilli hollow hair-like structures made of protein allows bacteria to attach to other cells and exchange genetic material Pilli-plural Pillus-singular 7 7 Major Structures of a Bacteria Cell Cytoplasm clear jelly-like material that makes up most of the cell 8 7 Major Structures of a Bacteria Cell Ribosomes cell part where proteins are made 9 7 Major Structures of a Bacteria Cell Chromosome a ring made up of DNA, contains most of bacterium’s genes 10 7 Major Structures of a Bacteria Cell Cell wall Thick outer covering that maintains the overall shape of the bacterial cell Prevents bursting in hypotonic environment 11 Plasmid • A few genes located in a small circular chromosome (may have one or more plasmids) • The key to resistance…bacteria pass on plasmids to other bacteria, and they typically code for resistance to antibiotics 12 3 Shapes of Bacteria Bacteria come in different shapes and sizes Spiral: spirillum rod-shaped: bacillus Round: coccus 13 Bacteria Arrangements • Diplo = pairs of cells • Staphylo = grape-like arrangment • Strepto = chain of cells 14 THE SIX KINGDOMS Archaebacteria Eubacteria 15 Archaebacteria Bacteria found in extreme environments 3 Types: 1. methane-producing (swamps, digestive tracts of cows & other mammals) 2. Salt-loving 3. Heat and acid loving (cracks in ocean floor, hot springs) 16 Anaerobic • Can live without oxygen – often oxygen would kill them • Ex. Bacteria in swamps 17 Eubacteria • Found: Almost everywhere • 3 Types: 1. Heterotrophs Parasites (feed on living organisms) Saprophytes (feed of dead organisms and waste) 2. Photosynthetic 3. Chemosynthetic 18 Chemosynthesis: • Making energy by breaking down sulfur and nitrogen compounds (ex. Bacteria convert N2 in the atmosphere into usable form for plants – nitrogen fixation) 19 Bacteria = prokaryote 3 differences between bacteria and animal cell 1. Bacteria= no nucleus, Animal = nucleus 2. Bacteria = Flagellum, Animal = no flagellum 3. Bacteria = cell wall, Animal = no cell wall 20 How can we get rid of bad bacteria? • Antibiotics = chemical that kills bacteria • The first antibiotic: 1929 – Penicillin (made from mold) 21 How does an antibiotic work? • Makes holes in cell wall causing the cells to rupture 22 Reproduction of Bacteria •Binary Fission- the process of one organism dividing into two organisms •Fission is a type of asexual reproduction •Asexual reproduction- reproduction of a living thing from only one parent How?... •The one main (circular) chromosome makes a copy of itself •Then the cell divides into two 23 Reproduction of Bacteria BINARY FISSION Bacteria dividing Completed 24 Sexual Reproduction = conjugation • Bacteria connect by pilli and transfer part of their chromosome Like an airport skyport transferring people! 25 Reproduction of Bacteria •The time of reproduction depends on how desirable the conditions are •Bacteria can rapidly reproduce themselves in warm, dark, and moist conditions •Some can reproduce every 20 minutes 26 Bacterial Cell & Nucleiod DNA Ring DNA replication Cell wall synthesis Cell separation 27 Bacteria Survival Endospore•a thick walled structure that forms inside the cell •they are the major cause of food poisoning •allows the bacteria to survive for many years •they can withstand boiling, freezing, and extremely dry conditions •it encloses all the nuclear materials and some cytoplasm 28 Bacteria Survival Bacillus subtilis Endospore-the black section in the middle highly resistant structures can withstand radiation, UV light, and 29 boiling at 120oC for 15 minutes. Tetanus • Clostridium tetani • Produce a powerful nerve toxin • Endospores can exist almost anywhere, if get into a wound they germinate and produce toxin 30 Controlling Bacteria 3 ways to control bacteria: 1) Canning- the process of sealing food in airtight cans or jars after killing bacteria •endospores are killed during this process 2) Pasteurization- process of heating milk to kill harmful bacteria 3) Dehydration- removing water from food •Bacteria can’t grow when H2O is removed •example: uncooked noodles & cold cereal 31 Botulism • Clostridium botulinum • On foods, if foods aren’t canned properly they form an endospore and then germinate in the anaerobic environment of the can • Produce toxins – can cause food poisoning 32 Bacteria Survival – Food sources parasites – bacteria that feed on living things saprophytes – use dead materials for food (exclusively) decomposers – get food from breaking down dead matter into simple chemicals important- because they send minerals and other materials back into the soil so 33 other organisms can use them Harmful Bacteria • some bacteria cause diseases •Animals can pass diseases to humans Communicable Disease – Disease passed from one organism to another This can happen in several ways: •Air •Touching clothing, food, silverware, or toothbrush •Drinking water that contains bacteria 34 BLUE-GREEN BACTERIA Autotrophs – make their own food through photosynthesis larger than most bacterial cells commonly grow on water and surfaces that stay wet…such as rivers, creeks and dams Some live in salt water, snow, and acid water of hot springs food source for animals that live in the 36 water BLUE-GREEN BACTERIA can be toxic to humans and animals Blooms- occur when the bacteria multiplies in great numbers and form scum on the top of the water 37 Harmful Bacteria Human tooth with accumulation of bacterial plaque (smooth areas) and calcified tartar 38 (rough areas) Helpful Bacteria •Decomposers help recycle nutrients into the soil for other organisms to grow •Bacteria grow in the stomach of a cow to break down grass and hay •Most are used to make antibiotics •Some bacteria help make insulin •Used to make industrial chemicals 39 Helpful Bacteria E.coli on small intestines 40 Helpful Bacteria •Used to treat sewage Organic waste is consumed by the bacteria, used as nutrients by the bacteria, and is no longer present to produce odors, sludge, pollution, or unsightly mess. •foods like yogurt, cottage & Swiss cheese, sour cream, buttermilk are made from bacteria that grows in milk 41 The Wanted List • • • • Create flyers for a gallery of “Most Wanted” (beneficial bacteria) and “Least Wanted” (pathogenic bacteria). For each flyer: provide a mug shot (picture) of the bacterium name the bacterium (you can add humor, e.g., Sly the Salmonella typhi) indicate where it might be found (its natural hangout) specify it’s crime (e.g., poison suspect) or benefit (e.g., yogurt helper) 42 Controlling Bacteria Antiseptic vs. Disinfectants Antiseptic- chemicals that kill bacteria on living things •means – “against infection” Examples: iodine, hydrogen peroxide, alcohol, soap, mouthwash Disinfectants- stronger chemicals that destroy bacteria on objects or nonliving things 43