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 specialized
Most viruses are species-specific
Many viruses are also cell-specific

8. Viral Replication Cycles
Lytic 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

11. Lysogenic Cycle

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 organelles
2 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 Heterotrophs
Bacteria 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 Autotrophs
Bacteria that convert solar energy into food
Cyanobacteria or blue-green algae
Found in aquatic environments
Composed of chains of independent cells

18. Eubacteria: Chemosythetic Autotrophs
Break 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 Stain
Gram staining reflects differences in cell wall composition
Gram-positive bacteria stain blue/violet
Gram-negative bacteria stain pink

21. Identifying Bacteria: Shapes

22. Bacterial Reproduction
Asexually by binary fission
Very rapid at optimal conditions
can double every 20 minutes

23. Bacterial Reproduction
Sexually by conjugation

24. Common Bacterial Diseases
Agent
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 plants
Nitrogen 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 disks
ATB 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.