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Transcript
BACTERIA OBJECTIVES 19.1 Explain how the two groups of prokaryotes differ. Describe the factors that are used to identify prokaryotes Explain why bacteria are vital to maintaining the living world. 1 ____________ life covers nearly every square centimeter of the Earth. The smallest most common microorganisms are ____________ – unicellular and lack a nucleus. Prokaryotes typically range in size from 1 to 5 micrometers. there are exceptions as the one in the graphic, it is 500 micro meters long. Epulopiscium fisheloni 2 Until recently, all prokaryotes were placed in a single kingdom – _______. Monera has been divided into two different groups: the _______ and the ____________. Eubacteria, the larger of the two kingdoms of prokaryotes. Eubacteria live almost everywhere. The live in _____ and salt water, on land and on and within humans 3 E. coli 4 Eubacteria are usually surrounded by a cell wall (_________) that protects the cell from injury and determines its shape. Inside the cell ____ is a cell membrane that surrounds the cytoplasm. Some eubacteria has a second cell membrane that makes them especially resistant to damage. 5 Archaebacteria lack the peptidoglycan of eubacteria and also have different membrane _____. The DNA sequences of key archaebacterial genes are more like those of _________ than those of eubacteria. Many archaebacteria live in extremely harsh environments (methogens-thick mud without oxygen, some live in the Great Salt Lake or in hot springs) 6 Prokaryotes are identified by characteristics such as shape, the chemical nature of their cell walls, the way they move, and the way they obtain energy. ____ (spherical) ______ (rod-shaped) ______ (corkscrew) 7 Two different types of cell walls are found in eubacteria. A method called _____ stain consists of two dyes-one violet (the primary stain) and the other red (the counterstain). The violet stains peptidoglycan cell walls, followed by an alcohol wash, that is intended to wash out the stain. Gram-_______ bacteria have thicker walls that retain the dark color. 8 Gram-______ bacteria have thinner walls inside and outer lipid layer. Alcohol dissolves the lipid and removes the dye from the walls of the bacteria. The counterstain makes them appear ____ or light red. Some prokaryotes do not move at all, while other propel themselves with _______, a whiplike structure. Some lash, snake, or spiral forward. Still others glide slowly on a layer of ________ material they secrete. 9 Most prokaryotes get their energy from other organisms which means they are _________. Some, however, are autotrophs and make their own food from inorganic molecules. _____________ – heterotrophic prokaryotes that must take in organic molecules that supplies them with carbon. _________ – uses sunlight for energy, but they also need to take in organic compounds as a carbon source. 10 Photoautotrophs - uses ____ energy to convert CO2 and H2O to C compounds and O2 in a process similar to green plants. Ex. cyanobacteria (bluish pigment) Chemoautorophs – perform chemosynthesis, they make organic C from CO2. 2500 meters deep Instead of sunlight they use NH3, H2S, nitrites, S, or Fe 11 Hydrothermal vent 12 Obligate _____ – organism that require a constant supply of O2. Mycobacterium tuberculosis Obligate _______ – must live in the absence of O2. It can grow in canned food that has not been properly sterilized. 13 Closstridium botulinum ______ anaerobes – do not require O2, but neither is it _____ by its presence. Because of the ability to switch between living in and out of O2, they have the ability to live almost everywhere. 14 ____ fission occurs when a bacterium has grown to nearly 2X its size, it then replicates its DNA and divides into 2 daughter cells. It does not require the exchange of genetic information, it is an ______ form of reproduction. 15 Hollow bridge Many bacteria are able to exchange genetic information by a process called _______. During conjugation a hollow bridge forms between two bacterial cells, and genes move from one cell to the other (increases the genetic diversity). 16 When growth conditions are unfavorable, many bacteria form structures called ______. An endospore is formed when a bacterium produces a thick ______ wall that encloses its DNA. Spores remain _______ while waiting for more favorable growth conditions. 17 Bacteria are vital to maintaining the living world. Some are producers and capture energy by photosynthesis. Others are decomposers that break down the nutrients in dead matter and the atmosphere. Still other bacteria have human uses. 18 Every living thing depends directly or indirectly on a supply of raw materials. As decomposers, bacteria help the ecosystem recycle _______, which maintains an equilibrium in the environment. Bacteria breaks down complex compounds into simpler ones. 19 Plants and bacteria depend on bacteria for _______. Nitrogen makes up about ___ of the Earth’s atmosphere. Plants can not use nitrogen gas directly, it has to be changed to the compound _______ (NH3). The process of converting nitrogen gas into a form plants can use is called ________ _____. This allows N2 to be recycled in nature. 20 Many plants have a ______ relationships with nitrogen fixing bacteria. Soybeans and other legumes host the bacterium ______. Rhizombium grows in ______, or knobs, on the roots of the plant, and converts __ in the air into ammonia NH3 21 Uses for bacteria: 1.Used in production of foods and beverages. 2.Used in industry. 3.Digest petroleum. 4.Help to mine minerals. 5.Synthesize drugs and chemicals through genetic engineering. 22 VIRUSES OBJECTIVES: 19.2 Describe the structure of a virus. Explain how viruses cause infection. 23 _____ are particles of nucleic acid, protein, and in some cases, lipids. Viruses can only reproduce only by ______ living cells. All viruses no matter the size have one thing in common: They enter living cells and, one inside, use the machinery of the infected cell to produce more viruses. 24 A typical virus is composed of a core of ___ or ____ surrounded by a protein coat. A virus’s protein coat is called its _____, it has proteins that allows a virus to enter a host cell. Most viruses are highly ______ only being able to bond to certain sites. T4 bacteriophage Viruses that infect bacteria are called ___________. 25 In a ____ infection, a cell enters a cell makes copies of itself, and causes the cell to burst. Because the host cell is lysed and destroyed, this process is called a lytic infection. Other viruses, including the bacteriophage lamda, causes ______ infections in which the host cell makes copies fo the virus indefinitely. 26 In a lysogenic infection, a virus integrates its DNA in the DNA of the ____ cell, and the viral genetic information replicates along with the host cell’s DNA. The viral DNA is embedded in the host’s DNA is a ______. The prophage may remain part of the DNA of the host cell for many generations before becoming active. 27 Some types of cancer Aids Some viruses contain RNA as their genetic information and are called ________. When they infect a cell, they produce a DNA copy of their RNA, it is then inserted into the DNA of the host cell. Retroviruses get their name because their genetic information is copied _______ from RNA to DNA (retro means backward). 28 DISEASES CAUSED BY BACTERIA AND VIRUSES. OBJECTIVES: 19.3 Explain how bacteria cause disease. Describe how bacteria growth can be controlled. Explain how viruses cause disease. 29 ______ are disease-causing agents. All bacteria need nutrients and energy; however, disease results when bacteria interfere with the host’s ability to obtain enough of those elements. Many bacteria live on and within our bodies, and some help us perform essential functions, digesting food. 30 Louis Pasteur was the first person to show convincingly that _____ cause disease. He help establish the ____ theory. Bacteria produce disease in one of two general way. Some ____ the cell and tissues of the infected organism directly by breaking down the cells food. Some release ____ (poisons) that travel throughout the body interfering with the normal activity of the host 31 Healthy lung TB lung Caused by the bacterium Mycobacterium tuberculosis.32 _______ causes strep throat that release toxins in to the blood stream. Strep throat 33 Corynebacteria diphtheria, infects the tissue of the throat. ________ can lead to breathing problems, heart failure, parlaysis and death. 34 Many bacterial diseases can be prevented by stimulating the body’s immune system with _____. A ______ is a preparation of weakened or killed pathogen. When injected, a vaccine sometimes prompts the body to produce immunity to the disease. _________ is the body’s ability to destroy new pathogens. 35 If a bacterial infection occurs, ______ can be used to attack and destroy the bacteria. Antibiotics are compounds that block the growth and reproduction of bacteria. Animals are also infected with bacterial diseases, some also infects humans. Anthrax 36 There are various methods used to control bacterial growth, including sterilization, _______, and food processing. Sterilization destroys all bacteria by subjecting them to great ____. Most bacteria can not survive at ____ temperatures. Disinfectants are chemical solutions that kill _________ bacteria. _____ of antibacterial compounds increases the likelihood that ordinary bacteria will eventually evolve to become resistant to them. 37 Bacteria can cause food to ______. One method of stopping food from spoiling is storing it in a refrigerator. _____ temperature keeps food longer. Cooking techniques raises the temperature of the food to point where the bacteria is killed. Like bacteria, viruses produce disease by disrupting the body’s normal equilibrium. 38 Hepatitis A Small pox Chicken pox Measles Hepatitis C 39 Foot and mouth disease human 40 Viruses produce serious animal diseases as well. An epidemic of foot and mouth disease swept through Europe in the 1990’s. Thousands of cattle had to be destroyed in an effort to control the disease. The animal viruses, Rous sarcoma virus, causes ______ in chickens. Viruses also infect plants such as the tobacco ________ virus. Plant viruses contain a core of nucleic acid and a protein coat 41 Most plant viruses have a difficult time entering the cells they infect. Partly because plant cells are surrounded by tough cell walls that viruses alone cannot break down. They take advantage of ____ or tears on the plant. Viruses can be spread by _____, because the feeding action causes and opening for the virus to enter. 42 Scientists have discovered two other viruslike particles that causes diseases. 1.____ causes disease in plants. They are single-stranded RNA molecules and has no surrounding capsid. They enter the cell and direct the synthesis of new viroids. They then disrupt the metabolism of the cell and stunt the growth of the entire plant. 43 2. _____ is short for “protein infectious particles Prions causes diseases by forming protein clumps. These clumps cause other proteins to become prions. Eventually, there so many prions in the nerve tissue that cells become damaged. Mad cow and Creutzfeldt-Jakob disease may be caused by prions. 44 45