 | Term | Definition |
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Blue |
In an acid fast stain, what color do non-acid-fast organisms stain? |
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Pink |
In an acid fast stain, what color do acid-fast organisms stain? |
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Purple |
In a Gram's stain, what color do gram+ organisms stain? |
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Pink |
In a Gram's stain, what color do gram- organisms stain? |
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Crystal violet, rinse, mordant of iodine, rinse with alcohol, counterstain with safranin |
What is used in performing a Gram's stain? |
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Negative |
nigrosin and Indian ink are used in what type of stain? |
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Negative |
This type of stain does not penetrate the bacterial cell but rather causes the area around the cell to be dark. |
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Heat |
What is used as a mordant in spore staining to help the uptake of the stain? |
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Safranin |
Used to stain the vegetative portion in spore staining. |
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Malachite green |
Used to stain the endospore in spore staining. |
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Pure culture |
A culture of microorganisms in which all cells are of a single type. |
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Negative |
The best way to determine bacterial size and cell morphology is to prepare a slide by a process called ________ staining. |
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Smear |
Sucess at bacterial staining depends on the preparation of a suitable _______ of the organism. |
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To ensure shrinkage will not occur during staining, otherwise, distortion of artifacts will occur or to kill microbes. |
Name one of the three goals in preparing a smear for staining. |
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Capsule |
Some bacterial cells are surrounded by an extracellular slime layer called a ________, and staining this layer cannot be accomplished by ordinary simple staining procedures. |
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True. |
Capsular staining combines the methods for the simple stain and the negative stain. True or False? |
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True. |
Most bacteria are killed by the effects of ultraviolet light. True or False? |
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False. |
Bacteria that form endospores are less resistant than vegetative cells to the effects of UV light. True or False? |
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True. |
Ultraviolet rays can cause eye injury if looked at directly. True or False? |
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Mordant |
The function of the ______ in Gram staining is to complex with crystal violet to form a relatively insoluble complex in the gram positive bacteria. |
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False. (It's gram positive that can do this). |
Old cultures of gram negative bacteria can convert to gram positive or gram variable and give erroneous results. True or False? |
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True. |
Heat is used in spore staining to enable the stain to penetrate the endospore, once there is not removed with either decolorizing agents or water. True or False? |
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True |
Acid-fast organisms will stain red or pink and non-acid fast organisms will stain blue. |
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False. |
Gram positive organisms will stain pink and gram negative organisms will stain purple. |
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Flagella |
The major organelles of motility in bacteria are: |
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True. |
Bacterial motility decrease with time so it is best to examine a wet mount slide immediately after it is prepared. |
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True. |
Brownian movement is vibrational movement caused by invisible molecules bombarding bacterial cells. |
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streak plate and pour plate methods. |
The two commonly used procedures to separate organisms into pure cultures are the: |
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True |
Both the streak and pour plate methods involve diluting the number of cells in a sample. |
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Standard plate count (aka viable count) |
The _____ is one of the most common methods for determining bacterial numbers in a sample. |
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Coliforms |
The safety of drinking water is dependent on there being no sewage contamination. The presence of ______ in potable water suggests the potential for disease. |
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30 and 300 |
After plates are innoculated and incubated, plates that have between _______ colonies are selected for counting. |
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Standard plate count. |
In this lab exercise, two methods are used to determine the number of bacteria present in a culture sample. Name one of them. |
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Discard canister |
When finished with a pipette, place it in the _______which contains disinfectant. |
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Streak plate and pour plate |
Name two commonly used procedures for obtaining pure cultures. |
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Pure colony |
a colony that is assumed to be the identical progeny of the original cell. |
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Simple staining |
The use of a single stain to color a bacterial cell is commonly referred to as: |
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Negative |
__________ stains such as nigrosin and india ink do not penetrate the bacterial cell but rather cause the background area around a cell to become opaque or dark. |
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Capsule or glycocalyx |
Some bacterial cells are surrounded by an extracellular slime layer called a ________ |
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Simple |
A basic dye is utilized to stain bacterial cells |
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Negative |
A stain that does not penetrate cells is used to color the background. |
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Crystal violet or methylene blue |
For the simple stain procedure, one can use: |
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India ink or nigrosin |
For the negative stain procedure, one can use: |
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Air-dried |
Before heat fixation, a wet smear of bacterial cells on a slide must first be: |
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Mycolic acid |
Bacteria which contain a waxy material in their cell walls called _______ are said to be acid-fast and appear pink or red when stained. |
