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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)

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

** 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

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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 chlorophyll3. 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

-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

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

very sticky capsule

pili in conjugation

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Prokaryote Characteristics

-ShapeBacillus: Rod shapedCoccus: Spherical (round)Spirillum: Spiral shape

-grouping patternsDiplo- Groups of twoStrepto- chainsStaphylo- Grapelike clusters

-Cell Wallsclassify bacteria based on cell walls (gram + or -)

-Movementflagella help bacteria move

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Streptococcus Causes Strep ThroatStaphylococcus

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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