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How do procaryotic cells divide?
- Binary Fission
- Exponentially
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What is generation time?
Time it takes for population to double
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What is a pure culture?
Population of cells derived from a single cell - all genetically identical.
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How do you obtain a pure culture?
Isolation of cells
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What is AGAR?
Gelatinous medium derived from red-algae.
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What is the streak plate method?
- Most common way of isolating bacteria.
- Bacteria streaked on a plate in different directions
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What are the growth phases of bacteria?
- Lag Phase - preparation for growth.
- Log Phase - Period of exponential growth
- Stationary Phase - Population growth remains stable; growth = death
- Death Phase - Number of viable cells decrease at a constant rate.
- Phase of Prolonged Decline - Very gradual decrease in population; may last days or years.
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What is a continuous culture?
Bacterial growth can be maintained exponentially.
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What are the major conditions that influence bacterial growth?
- Temperature
- Oxygen
- pH
- Water Availability
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What 5 categories are procaryotes divided into?
- Psychrophiles - freezing temps
- Psychrotrophs - cold temps
- Mesophiles - comfortable temperatures; disease causing
- Thermophiles - hot springs
- Hyperthermophiles - hydrothermal vents, volcanoes, usually archae
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What does aerobic and anaerobic mean?
- aerobic - oxygen
- anaerboic - no oxygen
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What is an obligate aerobe?
Must have oxygen to grow.
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What is an obligate anaerobe?
Can't have oxygen to grow
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What is a facultative anaerobe?
Grows better with oxygen.
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What is a microaerophile?
Must have very little oxygen to grow.
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What is an aerotolerant anaerobe?
Indifferent to oxygen - can grow with or without
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What is a heterotroph?
Human - uses organismal carbon as a nutirent source
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What is an autotroph?
Plants - uses inorganic carbon
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What is a phototroph?
Derives energy from sunlight.
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What is a chemotroph?
Derives energy from chemical compounds
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What is a complex media?
- Contains a variety of ingredients, with no exact formula.
- Example: Nurtient broth, Blood agar, Chocolate agar
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What is Differential media?
Allows you to distinguish between different organisms.
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What is selective media?
Only allows one selected organisms to grow.
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What is a direct cell count?
- A direct count of cells usually using a microscope
- Doesn't distinguish between living and dead cells.
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What is a direct microscopic count?
- Counted over a grid
- Quickest manual method
- Gives estimate
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What is a viable cell count?
Used to count living cells
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What is a plate count?
- Measures viable cells growing on solid culture
- Based on assumption that one cell gives rise to one colony
- Ideal to count between 30 and 300 colonies
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