Learning Target: Bacteria: The Good, the Bad, & the Ugly
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Learning Target: Bacteria: The Good, the Bad, & the Ugly
I Can…Describe how bacteria play both beneficial and negative roles in organisms and the ecosystemI 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
Learning Target: Bacteria: The Good, the Bad, & the Ugly
Bacteria:• 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
Learning Target: Bacteria: The Good, the Bad, & the Ugly
Bacteria:• Reproduce by:• Binary fission (Similar to mitosis)• Conjugation• Exchange of genetic material
through pili
Learning Target: Bacteria: The Good, the Bad, & the Ugly
Bacteria:• 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
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
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 PicklesSoy sauce Alcohol Vinegar
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
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
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
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]
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
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?
Learning Target: Bacteria: The Good, the Bad, & the Ugly
Antibiotic ResistanceResistance – 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
Learning Target: Bacteria: The Good, the Bad, & the Ugly
Antibiotic ResistanceCauses:• Overuse – creates selective pressure
favoring resistant bacteria over nonresistant
Learning Target: Bacteria: The Good, the Bad, & the Ugly
Antibiotic ResistanceCauses:• Underuse - only destroys the weakest
bacteria but not all leaving bacteria not initially killed alive to reproduce passing on some resistance
Learning Target: Bacteria: The Good, the Bad, & the Ugly
Antibiotic ResistanceCauses:• Misuse – Not effective on viral infection
(WHY?)• Agricultural feed overuse
Why does evolution happen so quickly in bacteria?
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