Chapter 18 Section 1: BACTERIA Main Idea: Prokaryotes are diverse organisms that live in nearly all environments.

Diversity of Prokaryotes

*Bacteria: prokaryotic organisms that belong to Domain Bacteria *Most numerous and earliest (first) organisms on Earth *Found nearly everywhere *Only organisms able to survive in hostile environments *Divided into 2 domains: 1. Domain Bacteria: - found everywhere except extreme environments -most studied organisms -contain a strong cell wall that contain peptidoglycan --> Gram Staining: Hans Gram (1884) **Gram Positive: Thick layer of peptidoglycan, stains purple, can be treated with antibiotics Bacterial Examples: Lactobacilli (makes yogurt & buttermilk) Actinomycetes (make antibiotics) Clostridium (lockjaw bacteria) Streptococcus (strep throat) Staphylococcus (staph infections)

** Gram Negative: Thin layer of peptidoglycan, stains pink or reddish, hard to treat with antibiotics Bacterial Examples: -Rickettsiae are parasitic bacteria carried by ticks...Cause Lyme disease & Rocky Mountain Spotted Fever -cyanobacteria

-some contain a second cell wall, a property which can be used to classify them. -some are photosynthetic

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2. Domain Archaea: - live in extreme environments - do not have a peptidoglycan layer -sub-divided into three groups: 1. Thermoacidophiles *hot, acidic environments (sulfur hot springs, thermal vents on the ocean floor, and around volcanic vents) *thrive in temperatures above 80 degrees Celsius & pH of 1-2 * many die in presence of oxygen! 2. Halophiles *live in very salty environments (use salt to generate ATP) *Great Salt Lake, Dead Sea (15% or more of salt) *usually aerobic *carry out photosynthesis using a protein instead of chlorophyll 3. Methanogens *can not live in presence of oxygen (obligate anaerobes) * uses CO2 during respiration and give off methane gas as a waste product *found in: sewage treatment plants, swamps, bogs, and near volcanic vents... also responsible for gases release from digestive tract... A.K.A. farts!

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Prokaryote Structure -chromosomes *small rings of DNA called plasmids (located in nucleoid region... NOT A NUCLEUS) -Capsule *surrounds the cell and keeps it from drying out and helps it to attach to surfaces in its environment. *shelters it from the effects of antibiotics

very sticky capsule

-Pili *Short protein appendages *Smaller than flagella *Adhere bacteria to surfaces *Used in conjugation for Exchange of genetic information *Aid Flotation by increasing buoyancy

pH: grow best at 6.5-7.0 pili in conjugation

-Size *typically 1-10 micrometers long and .7-1.5 micrometers wide

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Prokaryote Characteristics -Shape Bacillus: Rod shaped Coccus: Spherical (round) Spirillum: Spiral shape

-grouping patterns Diplo- Groups of two Strepto- chains Staphylo- Grapelike clusters

-Cell Walls classify bacteria based on cell walls (gram + or -) -Movement flagella help bacteria move

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Streptococcus Causes Strep Throat

Staphylococcus

Bacillus - E. coli

Streptobacilli

Spirillum

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Reproduction of Prokaryotes

Binary Fission -Bacteria reproduce asexually by binary fission -Single chromosome replicates & then cell divides -Rapid (20 minutes) -All new cells identical (clones)

Conjugation -Form a tube between 2 bacteria to exchange genetic material -Held together by pili -New cells NOT identical

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Metabolism of Prokaryotes -heterotrophs *must take in nutrients *decomposing organisms -photoautotrophs *simular to plants (require light for energy) *cyanobacteria *thought to be first organisms to release oxygen -chemoautotrophs * do not require light for energy * break down compounds that contain nitrogen or sulfur (ammonia for example)

Survival of Bacteria -endospores *structure produced during harsh conditions *thought of as a dormant cell *resistant to extreme heat/cold, dehydration, large amounts of ultra violet radiation (all typically would kill a bacterial cell) *anthrax, botulism, and tetanus= endospore producers -mutations *mutations and changes in DNA *antibiotic resistance

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Ecology of Bacteria -nutrient cyclying and nitrogen fixation *Nitrogen-fixing bacteria on a plant root nodule are able to remove nitrogen from the air and convert it into a form the plant can use *Bacteria are decomposers and can cycle nutrients through the environment.

-normal flora *harmless bacteria that live within your body *harmless e-coli that make vitamin K *some e-coli strands can cause food poisoning

-foods and medicines *uses for bacteria include making yogurt, cheese, and buttermilk. ***Some bacteria can degrade oil Used to clean up oil spills***

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-disease-causing agents *most bacteria doesn't cause disease but some do. *disease caused by bacteria can be in both plant and animal

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