1 Viruses and Bacteria Chapter 18

2 Pathogen Anything that causes a disease.

3 What is a virus? Considered non-living particles by most biologists because they: Do not carry out cellular respiration Do not grow and develop Cannot replicate on their own Viruses are named after: The disease they cause (poliovirus) The organ they infect (adenovirus)

4 Viral Structure 1. Genetic Material in the form of: Capsid: DNA RNA                                                                                       1. Genetic Material in the form of: DNA RNA Capsid: -outer protein coat

5 Viruses Herpes virus Adenovirus Polio virus

6 Bacteriophages “phage” Is a virus that attacks bacteria

7 Viruses are Specific Each virus is specializedMost viruses are species-specific Many viruses are also cell-specific

8 Viral Replication CyclesLytic Cycle (Fast and Furious) Kills the host cell Examples: Flu and Cold Lysogenic Cycle (Lingers) Similar to lytic cycle but does not immediately kill host cell Viral genetic material recombines with host cell’s DNA Examples: HIV, Herpes, and Chicken pox

9 AIMAR Lytic Cycle Step 1: A virus attaches to a host cell.                                                                         AIMAR Lytic Cycle Step 1: A virus attaches to a host cell. Step 2: Virus injects its genetic material into the host cell. Step 3: The enzymes make parts for more new viruses. Step 4: The new parts assemble into new viruses. Step 5: The new particles lyse (burst) from the host

10

11 Lysogenic Cycle

12

13 Vaccines They can't cause an infection, but the immune system still sees them as an enemy and produces antibodies in response. An antigen is like a name tag on a pathogen The next time your immune system encounters that pathogen/antigen it triggers a response to fight the infection.

14 Prokaryotes Unicellular organisms without membrane-bound organelles2 Kingdoms Archaebacteria Eubacteria

15 Archaebacteria Live in harsh environments 3 types Methane-producers“Methanogens” Marshes Lake sediments Animal digestive tracts Salt-dwellers “Halophiles” Dead Sea Heat/Acid-dwellers “Thermoacidophiles” Deep ocean vents

16 Eubacteria: The HeterotrophsBacteria that obtain their nutrients from elsewhere Some are parasites Feed off of living organisms Some are saprophytes Feed on dead organisms Feed on organic wastes (recyclers)

17 Eubacteria: Photosynthetic AutotrophsBacteria that convert solar energy into food Cyanobacteria or blue-green algae Found in aquatic environments Composed of chains of independent cells

18 Eubacteria: Chemosythetic AutotrophsBreak down and release energy from inorganic compounds such as H2S Important in converting atmospheric nitrogen into usable forms plants need Nitrogen Fixation

19 Structure

20 Identifying Bacteria: Gram StainGram staining reflects differences in cell wall composition Gram-positive bacteria stain blue/violet Gram-negative bacteria stain pink

21 Identifying Bacteria: Shapes

22 Bacterial ReproductionAsexually by binary fission Very rapid at optimal conditions can double every 20 minutes

23 Bacterial ReproductionSexually by conjugation

24 Common Bacterial DiseasesAgent Symptoms Treatment Strep Throat Streptococcus pyogenes sore throat, fever antibiotic Tetanus C. tetani stiff jaw, muscle spasm, paralysis antibiotic, clean wound Tuberculosis M. tuberculosis chronic cough, chest pain, blood in sputum Dental Caries S. mutans toothache remove decay Botulism C. botulinum blurred vision, paralysis, slurred speach antitoxins Cholera Vibrio cholera diarrhea, vomiting re-hydration, antibiotic Traveler's Diarrhea Escherichia coli stomach cramps, diarrhea

25 Beneficial Bacteria Converts Nitrogen into a usable form for plantsNitrogen Fixation N2 → NO2- + NO3- Converts Nitrogen into a usable form for plants Food Yogurt Cheese Pickles Sour cream Sauerkraut

26 ATB 1, 2, 3, 4, and 5 are all antibiotic disksATB 1, 2, 3, 4, and 5 are all antibiotic disks. The clear area around the disk after 24 hours represents the “zone of inhibition”, or the area in which the bacteria cannot grow. The larger the diameter of clear area, the more effective the antibiotic. 1) Which antibiotic disk is most effective? 2) Which antibiotic disk is least effective? 3) Antibiotics are chemicals used to control _____________. Read the bottom of pg. 161 and top of pg.162 1) Explain how antibiotics are used to kill bacteria. 2) Explain how antibiotic resistance can develop.