Post on 16-Dec-2015
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Earliest Prokaryotes
• Most numerous organisms on Earth
• Include all bacteria
• Earliest fossils date 2.5 billion years old
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Three Domains of Life
• Archaea – prokaryotes living in extreme habitats
• Bacteria- Cyanobacteria and eubacteria
• Eukarya – Protozoans, fungi, plants, & animals
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Archaebacteria
• Archaebacteria can live in extremely harsh environments
• They do not require oxygen and can live in extremely salty environments as well as extremely hot environments
• Called the Ancient bacteria
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Archaebacteria
• Lack peptidoglycan in cell walls
• Have different lipids in their cell membrane
• Different types of ribosomes
• Very different gene sequences
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Archaebacteria• Subdivided into 3 groups:
Methanogens- anaerobic, methagen producing
Thermoacidophiles- “heat and acid loving”
Extreme Halophiles- “salt-loving”
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Kingdoms of Bacteria
Eubacteria:Called the true
bacteriaMost bacteria are in
this group Include
photosynthetic Cyanobacteria
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Characteristics
3 basic shapes
• Bacillus: rod-shaped• Coccus: sphere-shaped• Spirrilla: spiral-shaped
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Bacterial Structure
• Microscopic prokaryotes
• No nucleus or membrane-bound organelles
• Contain ribosomes• Single, circular
chromosome in nucleoid region
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Bacterial Structure
• Have small rings of DNA called Plasmids
• Unicellular• Small in size (0.5 to 2μm)
PLASMIDS
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Flagella• Bacteria that
are motile have appendages called flagella
• Attached by Basal Body
• A bacteria can have one or many flagella
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Pili• Short protein
appendages• Smaller than flagella• Adhere bacteria to
surfaces• Used in conjugation
for Exchange of genetic information
• Aid Flotation by increasing buoyancy
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Protection
• Cell Wall made of Peptidoglycan
• May have a sticky coating called the Capsule for attachment to host or other bacteria
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Benefits of Bacteria
• Nitrogen Fixation• Photosynthesis• Decomposers• Food production- cheese
& yogurt• Sewage Treatment-
sludge to methane gas
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Modes of Nutrition• Saprobes – feed on
dead organic matter• Parasites – feed on a
host cell• Photoautotroph – use
sunlight to make food• Chemoautotroph –
oxidize inorganic matter such as iron or sulfur to make food
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Reproduction
• Bacteria reproduce asexually by binary fission
• Single chromosome replicates & then cell divides
• Rapid• All new cells identical
(clones)
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Reproduction
• Bacteria reproduce sexually by Conjugation
• Form a tube between 2 bacteria to exchange genetic material
• Held together by pili• New cells NOT
identical
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Pathological bacteria (disease-causing)
• Bubonic plague- wiped out part of Europe during the middle ages, fever, buboes (bubo-swollen gland) formed from bleeding lymph nodes.
• Cholera and typhoid fever- severe diarrhea, vomiting, often fatal, from contaminated water.
• Dental caries (cavities)- dental caries, holes form in teeth.
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Disease causing bacteria
• Diptheria- sore throat, fever, chills, thick gray coating on back of tongue.
• Dysentery- severe diarrhea, often bloody, can be fatal.
• Gangrene- affected area begins to necrofy (die) and rot.
• Gonorrhea- STD, inflammation of urinary and reproductive tracts, often leads to sterility in women.
• Lyme disease- carried by deer ticks, rash, pain, and swelling in joints.
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Disease causing bacteria
• Salmonella- causes severe food poisoning.
• Syphilis- STD, 1st stage includes canker sores, 2nd phase includes rash, 3rd stage includes insanity, fatal.
• Tetanus- “lock jaw,” found in soil and rust.
• Tuberculosis- known as TB, white death, consumption, infects lungs, coughing up blood, often fatal.