1. Learning Target: Bacteria: The Good, the Bad, & the Ugly
I Can…Describe how bacteria play both beneficial and negative roles in organisms and the ecosystem
I Will…
Explain how normal flora bacteria are beneficial in symbiotic relationships with host organisms
List examples of how bacteria are used to produce food products
List examples of how bacteria benefit the ecosystem
Describe examples of pathogenic bacteria
List reasons for the evolution of antibiotic resistant bacteria

2. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Single-celled prokaryotic organism (ALIVE)
No nucleus or membrane-bound organelles
Has a cell wall, but no chloroplast
Not an animal, not a plant
3 basic shapes
Sphere (cocci)
Rod (bacilli)
Spiral (spirilla)
Environment
Aerobes – oxygen
Anaerobes – CO2
Facultative aerobes -w/ or w/o O2

3. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Reproduce by:
Binary fission (Similar to mitosis)
Conjugation
Exchange of genetic material through pili

4. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Alive single celled organism
Reproduces by binary fission / conjugation
Invades cells or releases toxin
Treated with antibiotics
Virus:
Not alive protein capsid around nucleic acid
Cannot reproduce – needs host cell
Lytic cycle destroys cells
Treat symptoms while immune system defeats virus

5. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Normal flora – beneficial bacteria that exist on and in other organisms without harm
Often symbiotic (both life-forms benefit)
Animal digestive tracts
Helps breakdown indigestible material so nutrients can be absorbed
Synthesize vitamins to be absorbed
Keeps pathogenic organisms away (fill a niche)
e.g. E. coli in intestines
e.g. Staph epidermidis on skin

6. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Beneficial bacteria – Provides food and services for organisms and ecosystem
Fermentation – chemical breakdown of organic material (food) to add flavor and characteristics
Probiotics in foods assist immune and digestive system health
Yogurt
Cheese
Pickles
Soy sauce
Alcohol
Vinegar

7. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Ecosystem benefits –
Cyanobacteria produce oxygen (Blue-green algae)
Recycle Carbon (decompose organic material)
Nitrogen fixing (converts atmospheric nitrogen into ammonia to be absorbed by plants)
Legumes (peanuts)
Mutualistic

8. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Ecosystem benefits –
Bioremediation – process of using microbes to breakdown pollutants such as oil spills
Polluted water and beaches
Biodegradable – ability of bacteria to breakdown a substance
Plastics
Landfills

9. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Opportunistic Pathogens – Good bacteria gone Bad
Bacteria which are Normal flora and beneficial under certain conditions and environments
BUT
Change the environment or conditions and may become pathogenic
e.g. E. coli
Normal and beneficial in intestines
Leading cause of urinary tract infections

10. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Pathogens – Disease causing
Prior to medical revolution
Most deaths caused by bacterial infections
Sterile technique (disinfection)
Antibiotics
Alexander Fleming
1928 [1940s]

11. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Bacterial Pathogens
Two ways bacteria can cause disease
Invading and attacking cells (alters form & function)
Release toxins (poisons)
Stimulates immune response
Inflammation

12. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Antibiotics – Wonder Drug
Kills bacteria
Prevents reproduction
Affects formation of cell wall
Why do antibiotics kill bacteria and
not our cells?

13. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Antibiotic Resistance
Resistance – result of natural selection
Bacteria who are resistant and not killed by antibiotic survive and reproduce - passing on the resistant genes
Conjugation can exchange genetic material that carries instructions for resistance

14. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Antibiotic Resistance
Causes:
Overuse – creates selective pressure favoring resistant bacteria over nonresistant

15. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Antibiotic Resistance
Causes:
Underuse - only destroys the weakest bacteria but not all leaving bacteria not initially killed alive to reproduce passing on some resistance

16. Learning Target: Bacteria: The Good, the Bad, & the Ugly
Antibiotic Resistance
Causes:
Misuse – Not effective on viral infection (WHY?)
Agricultural feed overuse

17. Why does evolution happen so quickly in bacteria?