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Questions and Answers
What is the primary purpose of using media controls in a microbiology lab?
What is the primary purpose of using media controls in a microbiology lab?
- To accelerate the growth rate of inoculated media.
- To introduce a variety of microorganisms to the media.
- To ensure that all media is properly sterilized before use.
- To compare inoculated media to its original, uninoculated state. (correct)
In the context of microbiological examination, what is the distinction between 'results' and 'interpretations'?
In the context of microbiological examination, what is the distinction between 'results' and 'interpretations'?
- Results refer to the intended outcome of an experiment, while interpretations are unexpected findings.
- Results are subjective opinions, while interpretations are objective facts.
- Results are numerical data, while interpretations are qualitative descriptions.
- Results are direct observations, while interpretations explain the meaning of those observations. (correct)
Which of the following describes 'turbidity' in a broth culture?
Which of the following describes 'turbidity' in a broth culture?
- A film or membrane of bacteria floating on the surface.
- Growth concentrated at the bottom of the tube.
- Cloudiness or uniform dispersion of microbial growth throughout the broth. (correct)
- Clumps of bacteria floating throughout the broth.
How would you describe a 'pellicle' formation in a broth culture?
How would you describe a 'pellicle' formation in a broth culture?
What conclusion can be drawn from observing growth only at the bottom of a test tube with semi-solid agar?
What conclusion can be drawn from observing growth only at the bottom of a test tube with semi-solid agar?
In a semi-solid deep culture, what characteristic is indicated by growth spreading away from the inoculation point?
In a semi-solid deep culture, what characteristic is indicated by growth spreading away from the inoculation point?
What is the most likely interpretation of a slant culture showing even growth along the inoculation point?
What is the most likely interpretation of a slant culture showing even growth along the inoculation point?
If a slant culture demonstrates a root-like pattern of growth, which term best describes this arrangement?
If a slant culture demonstrates a root-like pattern of growth, which term best describes this arrangement?
Before discarding used test tubes in designated disposal containers, what crucial step must be taken?
Before discarding used test tubes in designated disposal containers, what crucial step must be taken?
What is the primary purpose of employing dilution streaking techniques in microbiology?
What is the primary purpose of employing dilution streaking techniques in microbiology?
Which streaking method is most effective for isolating individual colonies from a culture with multiple species?
Which streaking method is most effective for isolating individual colonies from a culture with multiple species?
What is the main objective of using the 4-quadrant streak plate method?
What is the main objective of using the 4-quadrant streak plate method?
How many bacterial species does a pure culture contain?
How many bacterial species does a pure culture contain?
What term describes a bacterial culture that contains two or more species?
What term describes a bacterial culture that contains two or more species?
What is the significance of obtaining isolated colonies on an agar plate?
What is the significance of obtaining isolated colonies on an agar plate?
What does the term 'confluent growth' on an agar plate indicate?
What does the term 'confluent growth' on an agar plate indicate?
What colony morphology is characterized by a smooth, circular edge?
What colony morphology is characterized by a smooth, circular edge?
When describing the elevation of a colony on an agar plate, which term indicates a base that is slightly raised?
When describing the elevation of a colony on an agar plate, which term indicates a base that is slightly raised?
What is the likely source of contamination if colonies appear away from the streak line on a streak plate?
What is the likely source of contamination if colonies appear away from the streak line on a streak plate?
What type of writing utensil should be used to label a petri dish?
What type of writing utensil should be used to label a petri dish?
What implement should you use to draw quadrant lines on a petri dish?
What implement should you use to draw quadrant lines on a petri dish?
When labeling tubes, which type of tape should one use?
When labeling tubes, which type of tape should one use?
Is it acceptable to draw quadrant lines on a petri dish with pencils?
Is it acceptable to draw quadrant lines on a petri dish with pencils?
When conducting the 4-quadrant streak method, how many plates are used?
When conducting the 4-quadrant streak method, how many plates are used?
If you are using 2 plates for the 4-quadrant streak method, how many plates should be streaked with a pure culture?
If you are using 2 plates for the 4-quadrant streak method, how many plates should be streaked with a pure culture?
Which of the following observations of bacterial growth in broth is characterized by clumps of bacteria floating throughout the liquid?
Which of the following observations of bacterial growth in broth is characterized by clumps of bacteria floating throughout the liquid?
Which of the following statements accurately describes the preparation and purpose of media controls?
Which of the following statements accurately describes the preparation and purpose of media controls?
What is the role of an inoculating loop or needle when used with culture media?
What is the role of an inoculating loop or needle when used with culture media?
Flashcards
Media controls
Media controls
Media that has been uninoculated and is sterile. Used as a baseline for comparison.
Result (in science)
Result (in science)
What is observed directly through the senses, particularly sight.
Interpretation (in science)
Interpretation (in science)
An explanation of what the results mean in the context of the experiment.
Broth (culture medium)
Broth (culture medium)
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Sediment (in broth)
Sediment (in broth)
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Turbidity (in broth)
Turbidity (in broth)
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Pellicle (in broth)
Pellicle (in broth)
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Flocculent (in broth)
Flocculent (in broth)
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Semi-solid deep
Semi-solid deep
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Strict aerobe/Obligate aerobe
Strict aerobe/Obligate aerobe
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Facultative anaerobe
Facultative anaerobe
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Strict anaerobe
Strict anaerobe
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Motile organisms
Motile organisms
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Non-motile organisms
Non-motile organisms
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Slant (culture medium)
Slant (culture medium)
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Arborescent
Arborescent
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Beaded
Beaded
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Rhizoid
Rhizoid
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Echinulate
Echinulate
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Effuse
Effuse
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Filiform
Filiform
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Dilution techniques
Dilution techniques
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Pure culture
Pure culture
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Mixed culture
Mixed culture
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Contamination
Contamination
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Colony
Colony
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Confluent growth
Confluent growth
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Circular colony
Circular colony
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Filamentous colonies
Filamentous colonies
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Irregular colonies
Irregular colonies
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Study Notes
- Media Controls
- Controls are media that has not been inoculated and is sterile
- Controls indicate the original appearance of the media
- Controls are available for test tube media, they offer a comparison point to identify changes or to recall the original appearance of the media
Results vs Interpretation
- Results are direct observations
- Results are what is seen
- Interpretation is understanding what each observation signifies
Culture Media - Broth:
- Broth is a liquid medium
- Broth is beneficial for growing large quantities of bacteria in a small space
- Broth needs to be inoculated using an inoculation loop
- Broth observations when assessing bacteria:
- Growth at the bottom of the tube is sediment
- Cloudy Broth is Turbidity, it appears as if the sample is foggy/murky
- A film/membrane of bacteria floating at the top of broth is a pellicle
- Clumps of bacteria floating in broth is flocculent
Culture Media - Semi-Solid Deep:
- Semi-solid deep utilizes a semi-solid medium containing 0.5%-0.7% agar
- Semi-solid deep is useful for identification of oxygen requirements and motility of a microbe
- Semi-solid deep needs to be inoculated using an inoculating needle
- Semi-solid deep observations when assessing bacteria:
- Growth only toward the top of the deep suggests it is a strict/obligate aerobe
- Growth from the top to the bottom of the deep suggests it is a facultative anaerobe
- Growth only at the bottom of the deep suggests it is a strict anaerobe
- Is motile if growth spreads away from the inoculation point or is "inverted" in a Christmas-tree shape
- Is non-motile if growth is only along the inoculation point
Culture Media - Slant:
- Slant utilizes a solid medium containing 1.5% agar
- Slant is primarily used for long-term storage of pure bacteria cultures
- Slant needs to be inoculated using an inoculation loop
- Slant observations when assessing bacteria:
- A branched growth pattern is arborescent
- Small colonies are beaded
- A root-like growth pattern is rhizoid
- A pointed growth pattern is echinulate
- Growth that grows beyond the inoculation point is effuse
- Even growth along the inoculation point is filiform
Test Tube Disposal
- Remove all tape from test tubes before disposal
- Place all tape-free tubes in the discard area referred to as orange racks
Dilution Techniques:
- Used for the Isolation of Bacteria
- Pour plate: bacterial culture + agar
- Spread plate: bacterial culture + solid media
- Streak plate: culture is diluted with each quadrant streak
- A 4 quadrant streak is a plate method
- Dilution techniques isolate different organisms from one another by diluting the original sample
4 Quadrant Streak:
- Useful to isolate mixed or contaminated cultures
- Used to obtain a pure culture
- A pure culture can be obtained by using further dilution techniques such as subculturing
Pure Culture vs Mixed Culture:
- Pure Culture is a bacterial culture that contains one bacterial species
- Mixed Culture is a bacterial culture that contains two or more bacterial species
- Contamination is bacterial culture that contains unwanted microorganisms
Colonies
- A colony originates from a single bacterial species
- Separate each species by obtaining isolated colonies
- Confluent growth purity cannot be determined via confluent growth alone
Culture Media - Plate:
- Plate utilizes a solid medium of 1.5% agar
- Plate is primarily used to isolate bacteria into individual colonies and to create a pure culture
- Plate needs to be inoculated using an inoculation loop
Plates Results and Interpretations:
- The whole colony appearance is circular, irregular, biconvex, filamentous, or rhizoid
- The margin/edge is entire, undulate, lobate, filamentous, or curled
- The elevation can be flat, raised, convex, or umbonate
Plate Label Requirements:
- Include:
- Name
- Lab section
- Date
- Organism's name
- Use wax pencils on petri dishes only
- Only use wax pencils to draw quadrant lines
- Use masking tape to label with water proof ink pens/Sharpie
- Do not label with pencils
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Description
Explore the use of controls in media preparation for microbiology. Understand how controls help in identifying changes and recalling original media appearances. Learn to interpret broth and semi-solid deep culture media observations, including sediment, turbidity, pellicle, and flocculent formations.
