bacteria basic structure: –prokaryotes (no nucleus or membrane-bound organelles) –single-celled...
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BACTERIA
• Basic structure:– Prokaryotes (no nucleus or membrane-bound
organelles)– Single-celled– Single circular piece of DNA– May have pili (attachment) or flagella
(movement)
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BACTERIA
Know the basic structure of a prokaryotic cell
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BACTERIABasic cell shapes:
• Bacillus: Rod- shaped cells:
• Coccus: Round-shaped cells:
• Spirillum: Spiral cells:
Be able to draw or recognize bacterial shapes by their names.
Draw these shapes in your notes.
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BACTERIANamed by arrangement
• Strepto: bacteria that form filaments are identified by this prefix. Example: streptococcus and streptobacillus
• Staphylo: species that form clusters are indicated by this prefix. Example: staphylococcus.
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BACTERIASTRUCTURE
• Capsules: outside of cell wall, gel-like layer• Types of cell walls:
– Gram positive: treatable with antibiotics– Gram negative: difficult to treat with antibiotics
• Endospores: some form thick walls around their chromosomes when exposed to harsh conditions.– May germinate years after they were formed
• Pili: adhere to surfaces and aid in conjugation– Exchange of genetic material with another bacterium
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BACTERIAObtaining energy
• Photosynthetic: – Cyanobacteria which are thought to have made
the Earth’s oxygen atmosphere
• Chemoautotrophic: obtain energy from inorganic molecules such as ammonia, or organic such as methane.– Many live in soil and help to fix nitrogen to a
form commonly used by plants
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BACTERIAObtaining energy, cont.
• Heterotrophic: Most bacteria– these bacteria are the principle decomposers
on Earth.– Can be aerobic or anaerobic– Both helpful and harmful
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BACTERIAPathogenic
• How do they harm us? By1. Metabolizing the host- breaking down organic
material of the host (i.e.. your tissue) and absorbing them.
2. Metabolizing secretions of the host- the bacteria that cause acne live in oil glands and feed off the oil produced by these glands. Bacterial growth causes pimples and blackheads
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BACTERIAPathogenic
3. By secreting toxins that cause illness in the host.
• Staph. aureus causes food poisoning
• Clostridium botulinum release toxins that affect nervous system (Botulism)
• E. coli 0157:H7 is found in raw or improperly cooked meat.
• Good news! Most bacteria are killed by boiling water, hot, soapy water, (washing hands) or by cooking food properly.
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BACTERIAThe Good Guys
1. Decay: without the actions of bacteria, most organic material would not decay, and there would be no recycling of nutrients in the ecosystem
2. Food Production: Yogurt. Many foods a product of fermentation (pickles, buttermilk, cheese, sourdough bread)
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BACTERIAThe Good Guys
3. Industrial uses: production of acetone and butanol for use in the production of other chemicals
4. Mining: reduce the amount of waste produced from certain ores. Also to convert sulfur in ore, leaving the desirable mineral behind
5. Environmental: Cleaning up oil spills