1. Chapter 19
Bacteria and Viruses

2. Section 19-1 Learning Targets
Explain how the two groups of prokaryotes differ
What are the factors used to identify prokaryotes
Explain why bacteria are vital to the living world.

3. Classification DOMAINS of Prokaryotic Organisms
1. BACTERIA: Contain peptidoglycan in cell walls
2. ARCHAEA: Do not contain peptidoglycan in cell walls.
KINGDOMS of Prokaryotic Organisms
1. Eubacteria
Live almost everywhere – soil; intestines of animals.
Cell wall with peptidoglycan – a carbohydrate.
EX: Escherichia coli (E. coli) – necessary for digestion in humans but can cause disease.

4. Structure of Eubacterium
Ribosome
Peptidoglycan
Cell Wall
Cell Membrane
Flagellum
Pili
DNA

5. Classification, cont’d.
KINGDOMS of Prokaryotic Organisms, cont’d.
2. Archaebacteria
Live in extremely harsh environments –hot springs; Great Salt Lake; mud.
Cell walls without peptidoglycan.
EX: Methanogen – produce methane gas in guts of animals.
Hot Spring in Yellowstone National Park

6. Identification of Prokaryotes
Prokaryotes are identified by:
Shape
Cell wall structure
Ways they move
Ways they obtain energy

7. Streptococcus pneumoniae --Chain of cocci that causes pneumonia
Shape
Cocci (Singular: coccus)
Round/spherical shape
Can form long chains or clumps/clusters
EX: Streptococcus and Pneumococcus form long chains
Streptococcus pneumoniae --Chain of cocci that causes pneumonia

8. Staphylococcus: Clusters of cocci.
Causes staph infections – “boils”
Diplococcus: A pair of cocci – can cause pneumonia

9. Shape Bacilli (Singular: bacillus) Rod-shaped bacterial cells
EX: E. coli found in the human intestine

10. Shape Spirilla (Singular: spirillum)
Spiral and corkscrew-shaped bacteria
EX: Syphilis (an STD caused by bacteria)

11. Cell Wall Structure Two types of cell walls in Eubacteria
A method called Gram staining is used to tell them apart
Cell walls containing mainly peptidoglycan
Called Gram positive Bacteria
Peptidoglycan in the cell wall only picks up the purple stain (appear purple under microscope)
Not as resistant to antibiotics
Cell walls with a second, outer layer of lipid and carbohydrate
Called Gram negative Bacteria
Wall only absorbs the red stain (appear pink under microscope)
More resistant to antibiotics

12. Movement Prokaryotes can also be identified by the way they move
Some propelled by flagella
Flagella: whip-like structures used for movement
Others lash or spiral forward
Some glide using slime they secrete
Others do not move at all

13. Forms of Nutrition
Prokaryotes have diverse adaptations that allow them to live in any environment
There are two types of prokaryotes based on the ways that they obtain energy
Autotrophs and Heterotrophs

14. Forms of Nutrition cont’d
AUTOTROPHS: Make their own food
Photoautotrophs: Use light to make food
Found where light is plentiful, near surfaces of lakes, streams and oceans
EX: Cyanobacteria
Chemoautotrophs: obtain energy directly from inorganic compounds such as hydrogen sulfide (H2S)
Get energy from chemical reactions
Found deep in the darkness of the ocean

15. Forms of Nutrition HETEROTROPHS: Obtain food from other sources
MOST bacteria are heterotrophs!
Chemoheterotrophs: use organic molecules for energy
EX: Staphylococcus aureus
Gets energy from food and release chemicals that cause food poisoning
EX: Salmonella, Clostridium botulinus
Photoheterotrophs: VERY unusual
Use light for energy and inorganic molecules for nutrition

16. Respiration Obligate Aerobes: Must have oxygen
EX: Tuberculosis infects lungs
Obligate Anaerobes: Do not tolerate oxygen
EX: Tetanus bacteria; botulism.
Facultative anaerobes: Do not require oxygen but are not harmed by it either
Found in many environments.

17. Bacterial Growth
When conditions are favorable, bacteria can grow and divide at astonishing rates!
Some as often as every 20 minutes….which means in just 48 hours the bacteria would reach a mass approximately 4000 times the mass of Earth!!!

18. Bacterial Growth and Reproduction
There are three ways bacteria grows and reproduces.
Binary Fission
Conjugation
Spore Formation

19. Reproduction/Growth Binary Fission: Divides into two; asexual
Most reproduce through binary fission

20. Reproduction/Growth Conjugation: Transfer of genetic material
Bridge forms between two cells, genes move from one cell to the other
Considered sexual-- increases genetic diversity
Can lead to antibiotic resistance in some bacteria
Conjugation Bridge

21. Reproduction/Growth Spore Formation
When growth conditions become unfavorable, many bacteria form spores
Spores called endospores when a thick wall encloses DNA and cytoplasm
Endospore can remain dormant until more favorable growth conditions arise
Dangerous; require high
temperatures and pressures
to destroy
Anthrax Endospore

22. Roles of Bacteria in Nature
1. Decomposers: Bacteria that help the ecosystem recycle nutrients
They break down dead matter into simpler substances
Bacteria are important in sewage decomposition
Example: rotten log; dead carcasses.

23. Roles of Bacteria in Nature
2. Aid in Digestion: In humans, termites and other organisms
EX: E. coli in human intestine
EX: Bacteria that digest cellulose in termites

24. Roles of Bacteria in Nature
3. Nitrogen Fixation: Process of converting nitrogen into a form plants can use
- Plants need nitrogen to make amino acids for proteins.
The nitrogen in the air cannot be used by plants until it is “FIXED” into ammonia or other nitrogen compounds
Bacteria fix the nitrogen for the plants to use

25. Nitrogen Fixation Example
Soybeans host the nitrogen-fixing bacteria Rhizobium on their roots.

26. Roles of Bacteria in Nature
4. Cause Disease: Only pathogenic bacteria cause disease (not all bad!)
Cause disease by damaging tissues or releasing toxins that harm the body
Treat with antibiotics: penicillin, tetracycline
Antibiotics: block growth and reproduction of bacteria
Tooth decay
Lyme disease
Tetanus
Tuberculosis
Salmonella food poisoning
Pneumonia
Cholera
Streptococcus mutans
Borrelia burgdorferi
Clostridium tetani
Mycobacterium tuberculosis
Salmonella enteritidis
Streptococcus pneumoniae
Vibrio cholerae
Regular dental hygiene
Protection from tick bites
Current tetanus vaccination
Vaccination
Proper food-handling practices
Maintaining good health
Clean water supplies
Disease
Pathogen
Prevention

27. Roles of Bacteria in Nature
5. Food Production: Bacteria used in the production of cheese, yogurt, vinegar and sour cream
Bacteria cause fermentation
6. In Industry: Bacteria can digest petroleum, remove waste from water and help mine minerals from ground
7. Biotechnology: Bacteria may be genetically engineered to produce medicines

28. Roles of Bacteria in Nature
8. Control Methods:
A. Disinfectants – alcohol, lysol;antiseptics
B. High heat and high pressures
C. Freezing – does not kill but controls
D. Drying, salting, pickling, preserving with sugar
E. Canning – pressure cooker
F. Antibiotics
9. Germ Warfare:
A. Anthrax – can be aerosolized and is very hardy
--Three days without treatment - death
--Can be treated with antibiotics.

29. Anthrax
infection
Bacillus anthracis