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Monerans Chapter 18 Bacteria & Viruses What is a Virus? You’ve probably had the flu— influenza—at some time during your life. Nonliving particles called viruses cause influenza. Viruses are composed of nucleic acids enclosed in a protein coat and are smaller than the smallest bacterium A cell in which a virus replicates is called the host cell Did You Know… Viruses are not They require a host considered to be alive cell by biologists because they don’t fulfill the criteria for life All they do is reproduce & they cant do that by them selves How are they named? Viruses are not given names Often named after the disease they cause EXAMPLE: RABIES VIRUS Poliovirus AIDS VIRUS How are they named? Others are named for the organ or tissue they infect EXAMPLE: ADENOVIRUSES adenoid tissue in the back of the throat Code Numbers are used to name several viruses infecting the same host Example: T-1 T-7 7 viruses that infect the intestinal bacteria E.coli (T stands for Type) How are they named? Bacteriophage is a virus that infects bacteria T-4 Viruses are Classified: Viruses are classified by Shape Consist of an inner core of nucleic acid surrounded by 1 or 2 protein coats The human flu virus may have another layer called a viral envelope surrounded by an outercoat Contains DNA & RNA but never both The arrangement of proteins give different shapes to viruses Shapes Viral coat is called capsids Polyhedral viruses (polio virus) resembles small crystals Tobacco mosaic viruses-small cylinders T-4 –looks like a lunar landing module Nucleic acid Capsid Attachment to a Host Before a virus can replicate, it must enter a host cell virus recognizes and attaches to a host cell when one of its proteins interlocks with a molecular shape that is the receptor site on the host cell’s plasma membrane. Lytic Cycle A virus cycle where the virus takes over the cell’s DNA and replicates until killing the cell A typical lytic cycle takes about 30 minutes and produces around 200 new viruses Lytic Cycle: To Break Down 1. Attachment 4. Assembly: nucleic acid & coats are 2. Entry: once inside the assembled into new virus destroys the viruses host DNA 5. Release: host cell 3. Replication: it breaks open & new reprograms the cells virus particles are metabolic activity to released copy the virus genes A. Attachment B. Entry C. Replication E. Lysis and Release D. Assembly Lytic Cycle Lysogenic cycle A virus cycle where the virus inserts its nucleic acid and lives in the cell without killing it Lysogenic Cycle Begins like the Lytic Cycle 2. Instead of destroying the host cell the DNA becomes part of the host 3. New DNA does not interfere with normal functions of the host cell 1. 4. Every time the host cell reproduces, virus is reproduced 5. Can continue undetected for many years, but can pop out at any time then the virus starts killing the host cells. A. Attachment and Entry LYSOGENIC CYCLE LYTIC CYCLE Lysogenic Cycle Explains why cold soars reappear, HIV & Flu virus can go undetected Where are Viruses found? Viruses are found everywhere… Some have been linked to cancers, animals, in plants Ex: Tobaacco mosaic virus Tobacco Mosaic Virus First plant virus to be identified There are more than 400 viruses that infect a variety of plants Virus can stunt the growth or yield a loss in the host plants Plant viruses require wounds, or insect bites to enter and infect the host Tobacco Mosaic Virus Some Types of Viruses Small Pox 30% of infected die Vaccines not administered to public since 1970’s No treatment, only preventative vaccine Used as a biological weapon The last case of smallpox in the United States was in 1949 Influenza A, B, & C Influenza types A or B viruses cause epidemics of disease almost every winter. In the U.S. influenza epidemics can cause illness in 10% to 20% of people average 36,000 deaths and 114,000 hospitalizations per year AIDS Virus HIV is the virus that causes AIDS. AIDS is a serious condition in which the body's defenses against some illnesses are broken down. Herpes Virus The virus Herpes simplex causes the common sexually transmitted disease genital herpes There are two types of Herpes Simplex, and both can cause genital herpes Most babies are born through c-section HPV Genital Warts:one of the most common types of sexually transmitted diseases Virus that causes them called the human papillomavirus http://www.thesahara.net /verrucas_plantar_warts. htm Bubonic Plague During the 1300s - a massive epidemic swept through Europe, killing onethird of the population by some estimates, and subsequently changing the course of European history. Referred to as The Black Death, Caused from being bitten by a rodent flea that is infected with the disease Polio Virus It enters through the mouth & is contagious. Phase 1: Fever, headache, sore throat, spewing, malaise(general bodily weakness and discomfort). Phase 2: Meningitis, fever, severe headaches, stiff neck and back, muscle pain. Phase 3: Muscle weakness and muscle paralysis, difficult swallowing, nasal voice, difficulty breathing SARS Originated in Asia in 2003 Stands for Acute Respiratory Syndrome and can be contracted by close person to person contact. When first introduced into the United States, SARS was thought to be a chemical weapon. West Nile Virus Virus carried by mosquitoes causing EEE. The most serious outbreak causes inflammation of the brain in humans and horses, as well as mortality in certain domestic and wild birds Ebola Virus Ebola Virus, common name for several strains of virus, three of which are known to cause hemorrhagic fever in humans, which is characterized by massive bleeding and destruction of internal tissues. Chicken Pox Chicken pox is a rash illness caused by a virus. Chicken pox usually occurs in childhood. More than 90% of Chicken pox cases occur in children less than 12 years of age. Anthrax Anthrax most commonly found in wild &domestic lower animals (cattle, sheep, goats, camels, antelopes They ingest spores from soil It can occur in humans when they are exposed to infected animals Or when anthrax spores are used as a bio-terrorist weapon Caused by the bacteria Bacilli Yellow Fever Yellow fever is a serious viral infection, transmitted by mosquitoes in tropical regions There are no medicines that are effective against this virus Bacteria Monerans: Classified into 2 different groups 1. Archaebacteria: the earliest Moneran. 2. Eubacteria: Heterotrophs. Archaebactera There are three types of archaebacteria that live mainly in extreme habitats where there is usually no free oxygen available. #1. Groups that live in an oxygen-free environment & produce methane Found in swamps, marshes, sewage treatment plants, digestive tracts of animals • These methane-producing archaebacteria live in marshes, lake sediments, and the digestive tracts of some mammals, such as cows and sewage disposal plants, where they play a role in the breakdown of sewage. #2 Groups that can live only in bodies of concentrated salt water Ex: Great Salt Lakes Ex: Dead Sea #3 Groups found in hot, acidic waters of sulfur springs undersea volcanic vents, acidic hot springs, salty water Eubacteria: The Heterotrophs Display a wide array of habitats a. Found everywhere: these bacteria need organics molecules as an energy source. Eubacteria: The Heterotrophs b. Group of photosynthetic autotrophs obtain energy from light Example: Cyanobacteria: Bluegreen bacteria Eubacteria: The Heterotrophs c. Chemosynthetic autotrophs: obtain energy from breakdown of inorganic substances like sulfur & nitrogen compounds. What is a bacterium? Only prokaryotic cell Contains cell wall which prevents cell from bursting B/c of No Nucleus, bacteria reproduce by binary fussion by copying its chromosoems Structures of Monerans Bacteria are often classified by the shapes of their cells 1. Sphere: Coccus [round] 2. Rods: Bacillus [Rod Shaped] 3. Spirals: Spirillum Bacterial cells are also classified by their arrangements Diplo – Two Bacteria can occur in pairs diplo- bacilli or cocci Staphlyo – Clusters Staphylococci cause “staph” infections Strepto – Long Chain Streptococcus cause infections such as “strep” throat Some well known Bacteria Streptococcus mutans causes tooth decay by converting sugars to an acid That erodes the tooth Clostridium botulinum produces a poison causing food poisoning Treponema pallidum causes syphlis The importance of bacteria Soybeans have nodules on their roots that convert nitrogen gas to ammonia that is used by the plant Foods & Medicines some foods would not exist without bacteria Swiss cheese Distinctive flavors vinegar Crispy Pickles sauerkraut Check out this web page by the USDA titled The Bad Bug Book