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UNIT VI Chapter 19 Bacteria and Viruses Chapter 19: Bacteria and Viruses I. Bacteria A. Prokaryotes- (single-celled organisms that lack a nucleus) 1. Classifying Prokaryotes (2 main groups) a. Eubacteria- (larger of two Kingdoms) includes wide range of organisms with different lifestyles. Cell wall of peptidoglycan (a carbohydrate) b. Archaebacteria- (may be ancestors of eukaryotes) cell wall lacks peptidoglycan. DNA more like those of eukaryotes than eubacteria. Live extremely harsh environments (e.g. Around thermal vents, methanogens in digestive tracts of animals c. Cell Walls- two different types in Eubacteria 1. Gram positive- bacteria stains violet blue; peptidoglycan is made of carbs 2. Gram negative- bacteria stains red; cell wall Is made of lipid (fats) Two different types of cell walls are found in eubacteria. A method called Gram staining is used to tell them apart. Bacterial cells with a cell wall containing mainly peptidoglycan absorb only violet dye. Other bacteria have a second, outer, layer of lipid and carbohydrate molecules and absorb only the red stain. d. Identifying Prokaryotes (by shapes, chemicals of cell wall, way they move, method of obtaining energy) 1). Shapes- bacilli (rod-shaped), cocci (spherical), and spirilla (corkscrew-shaped) 2). Movement- some move by flagella, or glide through slime-like material, or no movement 3). Obtaining Energy a). Photoautotrophs- photosynthetic (make own food) b). Chemoautotrophs- obtain energy from inorganic molecules. Eat chemicals (e.g. Hydrogen sulfide gas) c). Heterotrophs- includes most prokaryotes. Obtain energy by taking in organic molecules and breaking them down. d). Photoheterotrophs- both photo. and hetero. 4). Releasing Energy a). Obligate aerobes- require constant supply of oxygen to live (cellular respiration) b). Obligate anaerobes- must live in absence of oxygen (e.g. Clostridium botulinum) rely on fermentation c). Facultative anaerobes- do not require oxygen but are not poisoned by it either. Can use either cellular respiration or fermentation. Botulism, a kind of food poisoning, is caused by the bacterium Clostridium botulinum. This type of bacterium is often found in foods that have not been properly sterilized. 5. Growth and Reproduction a. Binary fision- divides in half producing identical daughter cells (asexual) b. Conjugation- form bridge between two cells and transfer genetic materialincreases genetic diversity (sexual) c. Endospore- when conditions bad, bacteria form thick internal wall enclosing DNA and portion of cytoplasm. Can remain dormant for months or years Anthrax spores B. Bacteria in Nature 1. Decomposers- return nutrients to ecosystem 2. Nitrogen fixers- convert atmospheric nitrogen into form that the plants can use –ammonia (NH3) Many plants have symbiotic relationship with nitrogenfixing bacteria. The knoblike structures on the roots of this soybean plant are called nodules. Within these nodules are the rod-shaped, nitrogen-fixing bacteria Rhixobium 3. Bacteria and disease- only a few cause disease (pathogens) The “Dance of Death” was common during the bubonic plague. a. Some damage tissues of infected organisms by directly breaking them down for food. (e.g. Flesh Eating Bacteria) b. Some release toxins (poisons) (e.g. botulism) c. Many bacterial diseases can be prevented by stimulating bodies immune system with vaccines Vaccines can be used to prevent infection by the tuberculosis bacterium Mycobacterium tuberculosis d. Antibiotics- compounds that block growth and reproduction of bacteria e. Human uses of Bacteria- used in production of variety of foods (cheese, yogurt, buttermilk, sourcream, etc. ) f. Controlling bacteria- can be killed by heat or chemicals (sterilization) The practice of using antiseptics in the care and treatment of wounds was begun by the English surgeon Joseph Lister in 1868. Basing his work on the findings of the German physiologist Theodor Schwann and the French biochemist Louis Pasteur, Lister disinfected surgical and accidental wounds with a solution of carbolic acid, and in five years reduced the death rate from major amputations from 45 percent to about 12 percent. Many other antiseptics have come into use, among which the most important are mercury dichloride, iodine, boric acid, alcohol, the hypochlorites, mercurochrome, and Merthiolate. Chlorine is used in the sterilization of water, especially in public water systems and swimming pools. Streptococcus Tooth decay mutans Borrelia Lymeburgdorferi disease Leprosy- this chronic infectious disease usually affects the skin and peripheral nerves but has a wide range of possible clinical manifestations. Leprosy is caused by a bacillus, Mycobacterium leprae, that multiplies very slowly and mainly affects the skin, nerves, and mucous membranes. Necrotizing Fasciitis (Flesh eating bacteria) Streptococcus pyogenes II. Viruses (from Latin word for “poison”) A. What is a Virus? 1. Very small (need electron microscope to see) 2. Core of DNA or RNA surrounded by protein coat (capsid) with surface receptors (to recognize the cell they want to attack) a. Protein coat called capsid (proteins enable virus to enter host cell) b. Once inside, viral gene takes over Herpes virus B. Viral Infection- most viruses very specific (e.g. bacteriophage-infects bacteria) 1. Lytic Infection- virus enters a cell and makes copies of itself, and causes the cell to burst (cell lyses) 2. Lysogenic Infection- a virus embeds it’s DNA into the DNA of the host cell and is replicated along with the host cell’s DNA a. Lysogenic viruses do not lyse the host cell right away b. Eventually, several factors will activate DNA of virus to begin synthesizing new virus particles C. Viruses and Disease- cause polio, measles, AIDS, mumps, influenza, yellow fever, rabies, common cold, etc. Influenza Ebolavirus virus Small pox 1. Vaccines- used to prevent viral infections- when injected into body, stimulates the immune system (take out DNA so WBC learns to recognize virus) 2. retroviruses- contain RNA as genetic information (e.g. HIV, hantaviruses) HIV is an example of a retrovirus, which contains RNA as its genetic material. Retroviruses get their name because their genetic information is first copied backward from RNA to DNA 3. Prions- stands for “Protein infectious particles” Protein only- no DNA or RNA. Mad cause “Mad Cow Disease” . Attack the brain. Prions may cause several infectious diseases, including mad cow disease and scrapie (infectious disease in sheep). Experiments suggest disease caused by protein segments found in brain C. Are Viruses Alive? Not considered to be alive. Lack certain characteristics of life. Living things….. •Are made up of units called cells •Reproduce •Are based on universal genetic code •Grow and develop •Obtain and use materials and energy •Respond to their environment •Maintain stable internal environment •Taken as group, living things change over time Chapter 19 Bacteria and Viruses The structure in the figure represents a(an) a. virus. b. archaebacterium. c. methanogen. d. eubacterium. The structure in the figure represents a(an) a. virus. b. archaebacterium. c. methanogen. d. eubacterium. The figure below shows how prokaryotes can be identified by a. the composition of their cell walls. b. their reaction to the Gram stain. c. their cell shapes. d. their methods for obtaining energy. The figure below shows how prokaryotes can be identified by a. the composition of their cell walls. b. their reaction to the Gram stain. c. their cell shapes. d. their methods for obtaining energy. Which structures in the figure below is a cocci? a. A b. B c. C d. none of the above Which structures in the figure below is a cocci? a. A b. B c. C d. none of the above Bacilli, cocci, and spirilla refer to common a. Gram stains. b. shapes of prokaryotes. c. methods of prokaryotic movement. d. ways that prokaryotes obtain energy. Bacilli, cocci, and spirilla refer to common a. Gram stains. b. shapes of prokaryotes. c. methods of prokaryotic movement. d. ways that prokaryotes obtain energy. Which of the following are factors used to identify prokaryotes? a. cell shape b. the way prokaryotes move c. the way prokaryotes obtain energy d. all of the above Which of the following are factors used to identify prokaryotes? a. cell shape b. the way prokaryotes move c. the way prokaryotes obtain energy d. all of the above Unlike photoautotrophs, chemoautotrophs obtain energy a. directly from the sun. b. directly from inorganic molecules. c. indirectly from organic molecules. d. indirectly from other organisms. Unlike photoautotrophs, chemoautotrophs obtain energy a. directly from the sun. b. directly from inorganic molecules. c. indirectly from organic molecules. d. indirectly from other organisms. Most prokaryotes are a. heterotrophs. b. photoautotrophs. c. chemoautotrophs. d. photoheterotrophs. Most prokaryotes are a. heterotrophs. b. photoautotrophs. c. chemoautotrophs. d. photoheterotrophs. A method called Gram staining is used to tell a. what shape a prokaryote has. b. how a prokaryote obtains energy. c. what kind of cell wall a prokaryote has. d. whether a prokaryote has flagella or not. A method called Gram staining is used to tell a. what shape a prokaryote has. b. how a prokaryote obtains energy. c. what kind of cell wall a prokaryote ha d. whether a prokaryote has flagella or not. As decomposers, bacteria a. fix nitrogen. b. carry out photosynthesis. c. fight off viruses. d. recycle nutrients. As decomposers, bacteria a. fix nitrogen. b. carry out photosynthesis. c. fight off viruses. d. recycle nutrients. In which of the following places are you most likely to find nitrogen-fixing bacteria? a. the atmosphere b. lakes and streams c. the roots of soybean plants d. a bag of nitrogen fertilizer In which of the following places are you most likely to find nitrogen-fixing bacteria? a. the atmosphere b. lakes and streams c. the roots of soybean plants d. a bag of nitrogen fertilizer Food poisoning is an example of bacteria a. releasing toxins that make you sick. b. breaking down the body's tissues. c. resisting antibiotics. d. going through the lytic cycle. Food poisoning is an example of bacteria a. releasing toxins that make you sick. b. breaking down the body's tissues. c. resisting antibiotics. d. going through the lytic cycle. The few bacteria that cause disease are called a. viruses. b. pathogens. c. endospores. d. antibiotics. The few bacteria that cause disease are called a. viruses. b. pathogens. c. endospores. d. antibiotics. Which of the following diseases is NOT caused by bacteria? a. tooth decay b. tuberculosis c. AIDS d. Salmonella food poisoning Which of the following diseases is NOT caused by bacteria? a. tooth decay b. tuberculosis c. AIDS d. Salmonella food poisoning Bacteria are used to make which of the following foods? a. cheese b. yogurt c. pickles d. all of the above Bacteria are used to make which of the following foods? a. cheese b. yogurt c. pickles d. all of the above Food that is stored in your refrigerator will keep longer because the bacteria that spoil food a. die at low temperatures. b. grow more slowly at low temperatures. c. require light to live. d. grow more slowly in the dark. Food that is stored in your refrigerator will keep longer because the bacteria that spoil food a. die at low temperatures. b. grow more slowly at low temperature c. require light to live. d. grow more slowly in the dark. Which of the following is a characteristic of bacteria that is key to keeping them under control? a. Most bacteria cannot survive high temperatures for long periods. b. Most bacteria are resistant to harmful chemicals. c. Most bacteria form endospores when subjected to harsh conditions. d. Most bacteria do not attack human foods. Which of the following is a characteristic of bacteria that is key to keeping them under control? a. Most bacteria cannot survive high temperatures for long periods. b. Most bacteria are resistant to harmful chemicals. c. Most bacteria form endospores when subjected to harsh conditions. d. Most bacteria do not attack human foods. Which of the following is NOT a form of sterilization? a. refrigeration b. boiling c. chemical disinfection d. frying Which of the following is NOT a form of sterilization? a. refrigeration b. boiling c. chemical disinfection d. frying A virus's outer protein coat is called a a. DNA core. b. capsid. c. bacteriophage. d. tail sheath. A virus's outer protein coat is called a a. DNA core. b. capsid. c. bacteriophage. d. tail sheath. All viruses are made of proteins and a. nucleic acids. b. prophages. c. bacteriophages. d. endospores. All viruses are made of proteins and a. nucleic acids. b. prophages. c. bacteriophages. d. endospores. A viral capsid functions to a. bind the virus to the surface of a host cell. b. transcribe viral genes. c. force a host cell to make copies of the virus. d. destroy a host cell. A viral capsid functions to a. bind the virus to the surface of a host cell. b. transcribe viral genes. c. force a host cell to make copies of the virus. d. destroy a host cell. A lytic infection concludes with the a. embedding of viral DNA into the host cell's DNA . b. production of a prophage. c. bursting of the host cell. d. production of messenger RNA. A lytic infection concludes with the a. embedding of viral DNA into the host cell's DNA . b. production of a prophage. c. bursting of the host cell. d. production of messenger RNA. Bacteriophages infect a. other viruses. b. bacteria only. c. any available host cell. d. cells undergoing the lytic cycle. Bacteriophages infect a. other viruses. b. bacteria only. c. any available host cell. d. cells undergoing the lytic cycle. Unlike lytic viruses, lysogenic viruses do not a. inject their genetic material into the host cell. b. enter the lytic cycle. c. lyse the host cell right away. d. infect host cells. Unlike lytic viruses, lysogenic viruses do not a. inject their genetic material into the host cell. b. enter the lytic cycle. c. lyse the host cell right away. d. infect host cells. Viruses cause infection by a. producing toxins that harm the body. b. reproducing independently inside the body. c. forming endospores in the body. d. entering body cells and replicating. Viruses cause infection by a. producing toxins that harm the body. b. reproducing independently inside the body. c. forming endospores in the body. d. entering body cells and replicating.