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Bacteria

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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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Classification of Life

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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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Archaebacteria

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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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Grouping of Bacteria

• Diplo- Groups of two

• Strepto- chains• Staphylo- Grapelike clusters

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Diplococcus

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Streptobacilli

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Staphylococcus Bacterial

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Staphylococcus

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Spirillum

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Characteristics of

Bacteria

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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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Bacterial Cell

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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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Useful Bacteria

• Some bacteria can degrade oil

• Used to clean up oil spills

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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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Nutrition, and

Reproduction

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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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Cellular organism copies it’s genetic information then splits into two identical

daughter cells

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Binary Fission E. coli

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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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Conjugation

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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.