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Questions and Answers
What is a mixed culture?
What is a mixed culture?
A microbial culture consisting of two or more species.
What is a pure culture?
What is a pure culture?
Contains only one species.
What is a streak plate?
What is a streak plate?
The streak plate is an isolation technique where a bacterial sample is streaked over the surface of a plated agar medium.
What happens during streaking?
What happens during streaking?
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What happens to cells that have been sufficiently isolated?
What happens to cells that have been sufficiently isolated?
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What is a Colony-Forming Unit (CFU)?
What is a Colony-Forming Unit (CFU)?
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What is the purpose of all streak patterns?
What is the purpose of all streak patterns?
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Which streak(s) are used with samples suspected of high cell density?
Which streak(s) are used with samples suspected of high cell density?
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For a 4 Quadrant streak, when do you sterilize the inoculating loop?
For a 4 Quadrant streak, when do you sterilize the inoculating loop?
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Which streak(s) are used with samples suspected of low cell density?
Which streak(s) are used with samples suspected of low cell density?
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How do you label media you are inoculating?
How do you label media you are inoculating?
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What should you do with bacterial stock cultures used in our lab?
What should you do with bacterial stock cultures used in our lab?
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What are two characteristics of agar that make it an ideal solidifying agent?
What are two characteristics of agar that make it an ideal solidifying agent?
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Study Notes
Microbial Cultures
- Mixed Culture: Comprises two or more species of microorganisms.
- Pure Culture: Contains a single species, essential for studying specific organisms.
Streak Plate Method
- Streak Plate Technique: Involves streaking a bacterial sample across an agar surface to isolate individual cells.
- Cell Density: During the streaking process, cell density diminishes, allowing for separation of cells on the agar surface.
- Isolated Cells Growth: Sufficiently isolated cells develop into colonies made up solely of the original cell type.
Colony Formation
- Colony-Forming Unit (CFU): Refers to the origin of colonies, which can arise from single cells, paired cells, chains, or clusters.
- Purpose of Streak Patterns: Designed to space deposited cells on agar, ensuring they grow into separate, isolated colonies.
Streak Patterns
- Quadrant Streak & T-Streak: Recommended for samples with high cell density to effectively isolate individual cells.
- Zig-Zag Streak: Ideal for samples with low cell density, allowing for broader distribution of cells.
Procedure and Labeling
- Sterilization of Inoculating Loop: Important to sterilize the loop after the first two streaks in a four-quadrant streak; not needed after the third streak.
- Proper Labeling of Media: Label using experiment number, date, initials, section number, and organism name for clear identification.
- Stock Culture Handling: Must use yellow labeling tape and avoid writing on tubes; label cultures before returning to the lab bench.
Agar Characteristics
- Ideal Solidifying Agent: Agar melts at 100°C and is not a nutritive substance, making it suitable for microbiological applications.
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Description
This quiz focuses on the Streak Plate Method of Isolation, a fundamental technique in microbiology used for isolating pure cultures from mixed ones. Key terms such as 'mixed culture', 'pure culture', and 'streak plate' are explored to enhance your understanding of microbial cultures and isolation methods.
