Viruses And Bacteria


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Viruses And Bacteria

  1. 1. CHAPTER 16 Prokaryotes and Viruses
  2. 2. PROKARYOTIC LIFE BEGAN ON A YOUNG EARTH <ul><li>Stromatolites are composed of thin layers of sediment pressed tightly together resembling layers in an onion. </li></ul><ul><li>The first organisms are found in these layers. </li></ul><ul><li>They are called cyanobacteria. </li></ul>
  4. 4. HOW DID LIFE BEGIN? <ul><li>There are many questions about how life began. </li></ul><ul><li>It is a total mystery but there are theories. </li></ul><ul><li>The Miller-Urey experiment showed that inorganic molecules can create organic ones. </li></ul><ul><li>Water is boiled into steam. </li></ul><ul><li>Methane, ammonia and hydrogen gas were present on early Earth. </li></ul><ul><li>Putting water vapor together with these compounds and putting an electric charge through them makes organic compounds. Pg. 357 </li></ul>
  6. 6. HOW DID LIFE BEGIN? <ul><li>Organic polymers have been made in lab conditions by dripping amino acids on hot surfaces. </li></ul><ul><li>The heat evaporates the water leaving behind high concentrations of amino acids bonded together. </li></ul>
  7. 7. THE RNA WORLD HYPOTHESIS <ul><li>What was the original process of copying hereditary information? </li></ul><ul><li>DNA strands can only copy themselves with the help of enzymes but single RNA strands can copy in solutions containing nucleotides without enzymes. </li></ul><ul><li>This theory is called the RNA World theory. </li></ul><ul><li>This could have been the basis for the first replication. </li></ul><ul><li>Experiments have shown that pre-cells or bubbles made of lipids can form around RNA polymers in a solution. </li></ul>
  8. 8. WHERE DID LIFE BEGIN? <ul><li>It is a mystery where live originated but some likely sites have been identified. </li></ul><ul><li>Some sites could be shallow water or moist sediments. </li></ul><ul><li>During Earth’s early history, the land surface may have been too hot for molecules or pre-cells to survive. </li></ul><ul><li>The discovery of deep-sea hydrothermal vents raised the possibility that energy and chemicals can from vents. </li></ul><ul><li>Today’s deep sea vents are populated by a huge diversity of life. </li></ul><ul><li>Most of this life is prokaryotic organisms. </li></ul>
  9. 9. DIVERSITY OF PROKARYOTIC LIFE <ul><li>Archaea comes from the Greek word meaning ancient. </li></ul><ul><li>Populate the most extreme places on Earth. </li></ul><ul><li>Many Archaea are called extremophiles which means lovers of the extreme. </li></ul><ul><li>Thermophiles live in boiling hot springs. </li></ul><ul><li>Halophiles live in salt environments. </li></ul><ul><li>Others live in volcanic lava, glaciers and environments where no oxygen is present. </li></ul>
  10. 10. ARCHAEA
  11. 11. DIFFERENCES BETWEEN BACTERIA AND ARCHAEABACTERIA <ul><li>Bacteria are prokaryotes that differ from Archaea in different ways. </li></ul><ul><li>1. There are key differences in the DNA and RNA. </li></ul><ul><li>2. There are differences in their types of RNA polymerases. </li></ul><ul><li>3. Introns are absent in bacteria but are present in some Archaea. </li></ul><ul><li>4. Certain antibiotics kill bacteria but have no effect on Archaea. </li></ul><ul><li>5. Bacterial cell walls contain peptidoglycan that is not present in Archaea or eukaryotes. </li></ul>
  12. 12. STRUCTURE AND FUNCTION OF BACTERIA <ul><li>Bacteria are distinguished by shape, type of cell wall and motility type. </li></ul>
  13. 13. BACTERIA HAVE THREE SHAPES. <ul><li>Cocci- spherical shapes that are sometimes formed in chains, clumps or clusters, Strep throat and pneumonia are this type </li></ul><ul><li>Bacilli- rod shaped such as E. coli that live in your intestines. </li></ul><ul><li>Spirochete- curved or spiral shape, this type causes Lyme disease </li></ul>
  14. 14. CELL WALL STRUCTURE <ul><li>Nearly all bacteria have a cell wall outside their plasma membrane. </li></ul>
  15. 15. PURPLE OR PINK? <ul><li>Bacteria are stained with two dyes, purple and pink to determine which antibiotics will work for each kind. </li></ul><ul><li>Gram positive retain the purple dye in their cell walls. </li></ul><ul><li>Gram negative do not retain the purple dye but retain the pink dye instead. </li></ul><ul><li>Some antibiotics will only work for one kind. </li></ul>Gram positive Gram negative
  16. 16. BACTERIAL MOTILITY <ul><li>Flagella- a long thin filament anchored to the plasma membrane , may be one or many anchored all over the bacteria </li></ul><ul><li>Pili- shorter and thinner filaments that help bacteria stick together in clumps </li></ul><ul><li>NOTE: The flagella and pili are different than the kinds you will observe in eukaryotes. </li></ul>
  17. 17. BACTERIAL REPRODUCTION <ul><li>Anybody good at math? </li></ul><ul><li>Better use a calculator! </li></ul>
  18. 18. MOST BACTERIA CAN COPY THEMSELVES EVERY 20 MINUTES! <ul><li>Binary fission-DNA duplicates and moves to opposite ends of the cell, then the cell divides </li></ul><ul><li>This method allows quick reproduction and is much simple than mitosis. </li></ul><ul><li>Allows for quick passing of mutant genes. (More on this later!) </li></ul>
  19. 19. GENETIC VARIATION <ul><li>Since bacteria do not undergo meiosis, they do not exchange genetic information, however, they can do other things. </li></ul><ul><li>Transformation occurs when some bacteria take up pieces of DNA from the environment and incorporate it into its genetic material. </li></ul><ul><li>In conjugation, two bacterial cells temporarily join and directly transfer genetic material between them. </li></ul><ul><li>Plasmids are separate rings of DNA apart from the cell’s main chromosomes. </li></ul><ul><li>Transduction is when viruses that infect bacteria carry their genes to another. </li></ul><ul><li>They are called bacteriophages. </li></ul><ul><li>Some bacteria can survive extended periods of very hostile conditions by forming specialized resting cells called endospores. </li></ul>
  21. 21. Modes of Nutrition Photoautotroph Sunlight CO 2 Chemoautotroph Inorganic chemicals Photoheterotroph Sunlight CO 2 Organic compounds Chemoheterotroph Organic compounds Organic compounds Type Energy Carbon
  22. 22. Modes of Nutrition <ul><li>Fossil evidence indicates that the photoautotrophic mode of nutrition is very ancient. </li></ul><ul><li>Cyanobacteria generate oxygen as a waste product of their photosynthesis. </li></ul><ul><li>Oxygen is toxic to many organisms. It attacks organic compounds. </li></ul><ul><li>Many early bacteria went extinct as the oxygen was created by cyanobacteria. </li></ul><ul><li>Some anaerobic bacteria or non-oxygen using bacteria, survive in areas where oxygen did not reach. </li></ul><ul><li>Their descendants are still alive today in oxygen-free environments. </li></ul>
  23. 23. Modes of Nutrition <ul><li>The rest of the organisms adapt to oxygen living. </li></ul><ul><li>Many prokaryotes perform essential function by breaking down or decomposing organic waste products and dead organisms. </li></ul><ul><li>Some species of bacteria convert nitrogen gas in the air to nitrogen compounds in the soil and water. </li></ul><ul><li>The converted nitrogen can be used by plants. </li></ul><ul><li>Humans have discovered many ways of using prokaryotes. </li></ul><ul><li>For example, the use of organisms to remove pollutants from water, air and soil is called bioremediation. </li></ul><ul><li>Genetic engineering of prokaryotes helps pharmacies create antibiotics and proteins for use in humans. Insulin is made this way. </li></ul>
  24. 24. How Bacteria Cause Illness <ul><li>Bacteria and other microorganisms that cause disease are called pathogens. </li></ul><ul><li>Most pathogenic bacteria cause disease by producing poisons. </li></ul><ul><li>Some bacteria produce proteins that cause illness while others produce cell wall secretion that lead to fever, aches and shock. </li></ul>
  25. 25. Defense Against Bacterial Diseases <ul><li>Since the discovery of bacteria, many disease have declined. </li></ul><ul><li>This is due to better health and sanitation procedures. </li></ul><ul><li>Much of the decline is due to antibiotics. </li></ul>
  26. 26. Diseases/Illnesses Caused By Bacteria <ul><li>MRSA </li></ul><ul><li>TSS (Toxic Shock Syndrome) </li></ul><ul><li>Pneumonia </li></ul><ul><li>Gonorrhea </li></ul><ul><li>Meningitis </li></ul><ul><li>Salmonella </li></ul><ul><li>E. Coli </li></ul><ul><li>Cholera </li></ul><ul><li>Bubonic plague </li></ul><ul><li>Botulism </li></ul><ul><li>Peptic ulcer </li></ul><ul><li>Anthrax </li></ul><ul><li>Typhoid </li></ul><ul><li>Staph </li></ul><ul><li>Strep throat </li></ul><ul><li>Sepsis </li></ul><ul><li>Chlamyadia </li></ul><ul><li>Tuberculosis </li></ul><ul><li>Syphilis </li></ul><ul><li>Leprosy </li></ul><ul><li>Diphtheria </li></ul><ul><li>Tetanus </li></ul><ul><li>Rocky mountain spotted fever </li></ul><ul><li>Lyme disease </li></ul>
  27. 27. VIRUS STRUCTURE <ul><li>The structure of a virus is well suited to its function; entering a host cell and reproducing. </li></ul><ul><li>A virus is composed of a relatively short piece of nucleic acid DNA or RNA surround by a protein coat. </li></ul><ul><li>Since a virus doesn’t have its own cellular machinery, it must use the host cell’s machinery to make copies of itself. </li></ul>
  28. 28. VIRUS REPLICATION <ul><li>Viruses that infect bacteria called bacteriophages reproduce in 2 ways. </li></ul><ul><li>In the lytic cycle, the phage attachs to the host cell and injects its DNA. </li></ul><ul><li>The host cell’s enzymes and synthesis machinery make copies of the viral DNA and the viral proteins. </li></ul><ul><li>The viral proteins and nucleic acids then assemble themselves inside the host cell making copies of the original infecting virus. </li></ul><ul><li>The host cell then bursts open and these offspring infect new host cells and repeat the cycle. </li></ul>
  29. 29. VIRUS REPLICATION <ul><li>In the lysogenic cycle, a virus injects it genes into the host. </li></ul><ul><li>The viral DNA then adds itself directly to the host cell’s DNA. </li></ul><ul><li>Each time the host cell reproduces, the viral DNA is copied along with the host’s DNA. </li></ul><ul><li>Occasionally, the viral DNA separates from the host DNA and starts a lytic cycle. </li></ul><ul><li>New phages are made and released. </li></ul>
  32. 32. VIRUSES AND DISEASE <ul><li>Some viruses use RNA as their genetic material. </li></ul><ul><li>Some viruses that use RNA are flu, the common cold, measles, mumps, HIV, and polio. </li></ul><ul><li>DNA viruses are herpes and hepatitis. </li></ul><ul><li>The way viruses cause disease is radically different from bacteria infections. </li></ul><ul><li>A virus uses the equipment of a host cell to reproduce therefore approaches to control and cure infection are different from bacterial infection controls. </li></ul>
  33. 33. VIRAL DISEASES/ILLNESSES <ul><li>Common cold (rhinovirus) </li></ul><ul><li>AIDS (HIV) </li></ul><ul><li>Measles </li></ul><ul><li>Mumps </li></ul><ul><li>Herpes (Many forms including chicken pox) </li></ul><ul><li>HPV (Human Papilloma Virus) </li></ul><ul><li>Hepatitis (A,B,C) </li></ul><ul><li>Mono </li></ul><ul><li>Bird flu </li></ul><ul><li>Ebola and Marburg </li></ul><ul><li>Smallpox </li></ul><ul><li>Dengue Fever </li></ul><ul><li>Yellow Fever </li></ul><ul><li>Polio </li></ul><ul><li>Lassa Fever </li></ul><ul><li>Meningitis (some forms) </li></ul><ul><li>West Nile </li></ul>
  34. 34. HIV: A RETROVIRUS <ul><li>HIV is a virus that causes AIDS. </li></ul><ul><li>It is particularly dangerous because it attacks our own immune system, the very thing meant to protect us. </li></ul><ul><li>HIV is different because it is called a retrovirus. </li></ul><ul><li>A retrovirus synthesizes DNA from RNA which is the opposite of what normally happens. </li></ul><ul><li>An HIV virus carries 2 copies of RNA instead of DNA. </li></ul><ul><li>The RNA then uses an enzyme called reverse transcriptase to form DNA from the RNA. </li></ul>
  35. 35. HIV: A RETROVIRUS <ul><li>The DNA integrates into the host DNA and takes over. </li></ul><ul><li>The viral DNA can be dormant for years but occasionally it is transcribed into RNA again and new viruses are made. </li></ul><ul><li>While the virus is inactive, the disease symptoms are not evidence. </li></ul><ul><li>Only when the virus reproduces and destroys host cells does an individual get AIDS. </li></ul>
  36. 36. HIV LIFE CYCLE
  37. 37. HIV
  39. 39. DEFENSE AGAINST VIRAL DISEASES <ul><li>The immune system is critical to fighting infections and provides the basis for a major medical weapon for preventing certain viral and bacterial infections from occurring. </li></ul><ul><li>This weapon is called the vaccine. </li></ul><ul><li>Vaccines are deactivated varieties or small pieces of pathogens that stimulate the immune system to defend against the actual pathogen. </li></ul>
  40. 40. THE FIRST VACCINE <ul><li>The first vaccine was made against the virus that causes smallpox, an often fatal disease. </li></ul><ul><li>Edward Jenner, a physician, discovered that milk maids who had been exposed to cowpox, a mild disease, were resistant to smallpox. </li></ul><ul><li>The two diseases were so similar that the immune system couldn’t tell them apart. </li></ul><ul><li>Jenner injected people with cowpox which then causes resistance to smallpox. </li></ul><ul><li>Currently, smallpox has been eradicated. </li></ul><ul><li>NOTE: Smallpox the disease is gone but not the virus. It’s “on ice” in a lab somewhere. </li></ul>