Term
What are two types of stains?
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Definition
1. Non-selective
2. Specific stain |
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Term
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Definition
- Stains all bacteria
- Used to determine morphology size an arrangement
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Term
| What is an example of non-selective stain? |
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Definition
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Term
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Definition
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Term
| What is an example of specfic staining? |
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Definition
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Term
| What are two types of dyes? |
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Definition
1. Basic dye
2. Acidic dye |
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Term
What charge is a basic dye? and how does it work?
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Definition
| It is a catonic (+) charge and it binds to (-) charge molecules such as nucleic acids, proteins on surfaces of bacteria cells |
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Term
What charge is an acidic dye? and how does it work? |
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Definition
It is an anionic (-) charge and it binds to (+) charge structures.
It stains the background.
An example of acidic dye is negrosin and congo red, eosin |
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Term
| What are two types of fixation? |
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Definition
1. Heat fixation
2. Chemical fixation |
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Term
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Definition
| Pass through a flame in order to preserve morphology strucutre within the cell is not like before fixation |
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Term
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Definition
| Use a chemical that penetrates the cell and protects the cellular structures |
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Term
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Definition
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Term
| What is an example of a simple stain? |
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Definition
| Methylene blue or other basic dyes |
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Term
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Definition
- Stain the background
- Shows overall morphology
- No heat fix
- Use for delicate cells, good for spirochettes and capsule
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Term
| What kind of dye do we use for capsule staining? |
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Definition
1. Methylene blue
2. Nigrosine
(1 drop each) |
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Term
| Capsule uses both simple and negative stain because? |
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Definition
| Simple stains the sample and negative stains the background |
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Term
| What is a capsule composed of? |
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Definition
- Polysaccharides
- Mostly water
- Microbes have genes that encode for capsule production
- Capsule formation is genetically controlled and subject to environmental modification
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Term
| What is the function of a capsule? |
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Definition
- Protection against phagocytosis
- Protection from dissication
- Aids in attachments to surfaces
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Term
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Definition
- Different results depeding upon cells chemistry.
- A gram stain is based upon differences in the bacteria cell wall
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Term
| How thick is the cell wall of a gram (+)? |
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Definition
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Term
| How thick is the cell wall of a gram (-) cell? |
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Definition
| Thin peptidoglycan/ cell wall |
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Term
| What are the difference between a gram (+) and gram (-) cell? |
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Definition
Gram (+):
- Thick peptidoglycan
- Teichoic acid
Gram (-):
- Thin peptidoglycan
- Lipids: attaches to LPS to O.M.
- Core polysacharrides that are (-)ly charged compenents
- O-antigens on the O.M. region of LPS
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Term
| What color does gram (+) stain? |
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Definition
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Term
| What color does gram (-) stain? |
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Definition
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Term
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Definition
| Primary stain of bacteria take up |
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Term
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Definition
| Increase the interaction between crystal violet and cell wall |
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Term
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Definition
Decolorization
Gram (+): thick wall crystal violet-iodine complex= retained
Gram (-): thin cell wall →crystal violet- iodine complex= will be bleached out |
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Term
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Definition
Counter stain
Basic dye stains and decolorizes gram (-) bacteria |
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Term
| What are the four steps of gram stain? |
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Definition
- Primary stain- [crystal violet- 1 min]
- Mordant- [gram iodine- 1 min]
- Decolorization- [ethanol- 20 sec]
- Counterstain- [ safranin- 20 sec]
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Term
| What is an example of a gram (-)? |
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Definition
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Term
| What is an example of gram (+) bacteria? |
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Definition
| B. megaterium or S. epidermidis |
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Term
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Definition
| Differential stain used to distinguish mycobacteria |
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Term
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Definition
| Mycolic acid lipid like material in their cell envelope |
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Term
| What kind of dye is used in acid fast staining? |
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Definition
Kin youn stain used carbolfuchsin dye
After decolorization step acid fast organism will stain red
Other non-acid fast will stain- Blue
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Term
| what are the limitations of gram staining? |
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Definition
- a fresh culture should be used because old gram positvie bacteria may decolorize and stain with safranin
- some organisms are gram variable, that is, some isolates may be gram positive, some gram negative and some have cells staining with both characteristics
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Term
| what is the role of capsule? |
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Definition
| protection of the bacteria |
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Term
| when is heat fixation used? why? |
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Definition
| heat fixation is used in differential staining because it immobilize the organisms so that it can be stained |
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Term
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Definition
contain chromophores their specificity is determined by chemical structure
ex. basic dyes are cationic and will react with negatively charged |
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