1. Bacteria
Chapter 18 Section 1

2. Characteristics of Bacteria
Prokaryotes- no nucleus
Unicellular
Live in nearly all environments
One circular chromosome
Smallest and simplest of all living things
Classified by their shape
Reproduction:
binary fission and
conjugation

3. 2 Domains Domain Archaea Domain Bacteria
The two domains differ in cell wall composition:
Cell walls of Bacteria contain peptidoglycan (which provides strength & gives shape)
Cell walls of Archaea do not

4. Archaea
Found in extreme habitats where little else lives. Often referred to as extremophiles.
Halophiles – live in very salty areas
Thermoacidophiles – live in very hot, acidic areas
Many are anaerobes (do not use oxygen)
Believed to have helped evolve the first atmosphere into what is seen today.

5. Eubacteria Vary widely in habitat, found almost everywhere
Vary in metabolism/nutrition:
Heterotrophic (consumers)
Autotrophic (cyanobacteria photosynthesize)

6. Bacterial Methods of Obtaining Energy
Photosynthetic bacteria
- food from sun
Chemoautotrophic bacteria
- food from chemicals (sulfur and nitrogen)
Heterotrophic bacteria
- decomposers, feed off of decaying organic
matter

7. Oxygen Needs of Bacteria
Aerobes – require oxygen
Anaerobes – do not require oxygen
Obligate anaerobes – cannot live in presence of oxygen
Facultative anaerobes – can live with or without oxygen

8. Classification of Bacteria
Can be grouped by shape, cell wall composition, and movement.
Shapes:
Coccus- round
Bacillus- rod
Spirillium- spiral
Types
Strepto- in strands
Staphylo- in clusters (grapes)
Ex. streptococcus – round in strand-form

9. Bacteria Characteristics
Most bacteria have a cell wall surrounding the cell membrane
Some bacteria have a gel like layer called a capsule (provides protection)

10. Bacterial Movement & Attachment
Flagella- move like a corkscrew to help propel
Pili- used to stick to surfaces, aids in conjugation (reproduction)

11. Bacterial Reproduction
Binary fission- asexual, clones itself
Conjugation- sexual, exchange genetic material, allows for spread of antibiotic resistant genes

12. Bacterial Survival
Some bacteria can survive in unfavorable environments.
Survival mechanisms:
Endospores – a structure produced by some bacteria when conditions are harsh
Ex: bacteria that cause anthrax, botulism and tetanus.
Mutations – changes in DNA, may allow bacteria to survive harsh conditions. May also lead to antibiotic resistance.

13. Disease-Causing Bacteria
Only a small percentage of bacteria actually cause disease.
2 ways bacteria can cause disease:
Multiply quickly at site of infection before body can destroy them
Secrete a toxin or other substance that causes harm.
Examples of human bacterial diseases:
strep throat, lyme disease, pneumonia, etc.

14. Antibiotics
Different antibiotics interfere with different cell processes
Examples: Penicillin, Amoxicillin, Tetracycline
Some bacteria have become resistant to antibiotics (due to mutations or over exposure)

15. Beneficial Bacteria
Many foods have bacteria in them (yogurt, swiss cheese)
Bacteria are important in nutrient cycling (nitrogen fixing bacteria)
Mining companies use chemoautotrophic bacteria to clean up spills
Normal flora – helpful bacteria that live in & on you

16. Practice Problem #1
Tuberculosis is caused by a bacterium, Mycobacterium tuberculosis. Many years ago, streptomycin easily controlled the bacterium. Now streptomycin is much less effective against the resistant M. tuberculosis. The increasing resistance of M. tuberculosis to streptomycin is most likely due to the increased —
a. use of streptomycin for bacterial infections
b. numbers of alternatives to streptomycin
c. artificial production of streptomycin
d. early detection of bacterial infections

17. Practice Problem #2
Which of these could be successfully treated with antibiotics?
Strep throat
Common cold
HIV
Influenza

18. Practice Problem #3
Which of the following choices is not a method of preventing bacterial illnesses from spreading in a meat-processing plant?
a. Using antibiotics to treat persons with food poisoning
b. Washing hands and utensils with hot soapy water
Use of gloves when handling raw meat
products
d. Treatment of work areas with chemical disinfectants