1. Chapter 19 Viruses and Bacteria
TB AIDS
TB = tuberculosis (bacteria), AIDS is a virus

2. Viruses Non-living particle Discovered by Wendell Stanley in 1935
Working with Tobacco Mosaic Virus (TMV)
Virology is the study of diseases, studied by virologists
Damaging tobacco crops as early as the 19th century
He showed that even after crystallization, when everything else died, the virus was still active!
Today is still studied as a model virus – does not affect humans!
Not all viruses are shaped like this…(surrounded by protein coat – capsid)

3. Diversity of Viruses

4. Common Viral Diseases Common cold Influenza (flu) Chickenpox
Rabies – transmitted through animals
Herpes – different types
HIV (the virus)/AIDS (the disease)
(can cause) Cancer

5. Zika Virus Spread to humans through infected mosquitoes
Mild symptoms unless…
Infection during pregnancy can result in microcephaly and other brain defects

6. Viral Replication – terms
Bacteriophage – viruses that infect bacteria (the host in which they replicate their genome)
Prophage – the viral DNA that is imbedded in the host’s DNA
Will ultimately direct the host DNA to synthesize new viruses
Stressful events: physical, emotional, environmental (exposed to radiation). These…
T4 Bacteriophage

7. Lytic Cycle Virulent Virus invades a host cell
Bacteriophages are one way this can happen
Immediately takes over the cell’s machinery – DNA, ATP, ribosomes, etc. to make copies of itself
Lyses (bursts) cell open to kill it and send its “viral army” out to infect other cells.

8. Lysogenic Cycle Temperate Virus invades a host cell
Combines with the host’s genome to make a (repressed) provirus
Replicates with the host
Can wait for years
Due to a stress-inducing event, it becomes active, the host recognizes it, and it’s “kicked out” of the cell.
Retroviruses (RNA)
Viruses can be either DNA or RNA (which would make them a retrovirus, produce a DNA copy of their RNA)

9. Prions and Viroids Prions
A typical grouping of proteins that act like viruses and take over your nerve cells.
Most often affect the brain
BSE (Bovine Spongioform Encephalopathy) aka mad cow disease
Cusp of Alzheimer’s research
Viroids
Smallest known particles able to reproduce.
As small as 250 nucleotides!
Virus-like
Able to disrupt plant cell metabolism
Plants affected: oranges, potatoes, and cucumbers.

10. Prions

11. BSE/Mad Cow Disease
Parts that no longer can be sold for consumption because they were affected

12. Viroids
Irish potato famine

13. Vaccines The best way to protect against most viral diseases
A preparation of weakened or killed virus or even just viral proteins injected into the human body
How does this help?
This vaccine stimulates the immune system, fortifying it in the event that the virus comes your way.

14. Microbiology
Bacteria are the most numerous and diverse of all organisms, and live anywhere on the planet.
There are two kingdoms of bacteria:
1. Archaebacteria (more ancient, examples here on this slide)
2. Eubacteria
E. coli. – archaebacteria!
Black smokers – bacteria form the base of the food chain (eaten by things like clams and shrimp).

15. Archaebacteria
Bacteria that do not contain peptidoglycan (a protein/carbohydrate used for structure/support) in their cell walls
This type of bacteria lives in extreme environments
Methanogens (anaerobic conditions)
Extreme halophiles (use salts to make their energy)
Thermoacidophiles (extreme temperatures & pH)
We’ll return to peptidolycan later.
So not in out bodies!
What’s the connection between pH and acidity?

16. Methanogens
Convert hydrogen and carbon Dioxide into methane gas (CH4) using an alternate form of photosynthesis (no oxygen!)
Found in swamp gas and sewage
Alternate form of photosynthesis – how they get their nutrients.
Middle picture – study done of these bacteria at Wake Forest university

17. Extreme Halophiles Survive and thrive in very salty conditions
Use this salt to generate ATP

18. Thermoacidophiles
Survive and thrive in extreme temperatures or extremely acidic environments
Example – hot springs

19. Gram Stain
Eubacteria contain peptidoglycan (sugar/protein) in their cell walls
Bacteria types can be determined by Gram staining.
Developed by Hans Gram in 1884 to differentiate between bacteria types.
Gram stain positive (eubacteria) bacteria will stain a violet color.
Ex. Listeria, Streptococcus
Gram stain negative (archaebacteria) bacteria will turn a red or pink once counter-stained.
Ex. Meningitis and Salmonella
Meningitis – swelling in the nervous system
Listeria and Salmonella – food

21. Shapes of Eubacteria
Bacilli – most STDs
Cocci – food poisonings

22. Even More Types of Bacteria
Obligate aerobes – require a constant supply of oxygen to live.
Humans and many species of bacteria
Obligate anaerobes – must live in the absence of oxygen
C. botulinum
Facultive anaerobes – can survive with or without oxygen
Impacts type of respiration; can survive in any environment!

23. Bacteria Diagram
What’s the difference between a prokaryote (bacteria) and a eukaryote?
DNA – in nucleoid
6th Period got here

24. Pili or Pilus What do you think its function is?
Found in gram-positive bacteria
Protein tubes with an adhesive tip that corresponds to a specific glycoprotein
Constantly making and losing pili to diversify tips
To attach to its host cell!
Pili are on side, not back (that’s flagella).

25. Binary Fission
Division of a bacterial cell into two genetically identical cells.
Origin of replication
One bacterial cell can become one billion in just 10 hours!
If conditions are unfavorable for reproduction, bacteria can form an endospore!

26. Genetic Recombination
Bacteria are asexual (previous slide)
BUT, there are three ways they can exchange genetic information:
Transformation – extracts DNA from an outside source
Transduction – virus uses part of bacterium to replicate its own DNA (review)
Conjugation – two bacteria bind together and one transfers DNA into the other

28. Diseases caused by Bacteria
Pathogen = disease causing agent
Three ways that bacteria can cause infectious diseases:
Metabolize their host (via food)
Secrete bacterial toxins
Biowarfare – Anthrax
Examples: Botulism and Salmonella (food poisoning), Lyme disease (ticks), Strep throat (Streptococcus)
Sterilization
Period 6 got here

29. Uses of Bacteria Nitrogen cycle Food Environmental Mining (video #2)
Uranium cleanup
Cheese making
Pickle making
Next slide has some videos showing this!

30. More Videos – watch at your leisure!
(flesh eating)