lol, we must be in the same class, b/c i have all of the same questions.
did u figure out the answer?
I think its a base ... qc the microbiology lab
Cute, from the best that I could find some sources say pH 7 and others had given a pH 8. But could not find a solid answer.
As a simple stain it would have to have a pH of <7. As we know, the charge on the cell is always going to be negative (an anion). In order to achieve a simple stain we want the stain attracted to the cell wall; therefore, the stain must be positively charged (a cation) for the opposite forces to attract. The more acidic the compound - the smaller its pH number with 7 being neutral. As we know, the [H]+ increases as the pH decreases becoming evermore positively charged.
Simple answer: <7
There are two types of stains, the simple stain and the differential stain. A simple stain colors all objects the same while a differential stain is used to spot differences in microorganisms. A gram stain is a differential stain, which is used to tell the difference in gram negative and gram positive bacteria. A simple stain would stain all the organisms the same and this difference would not be noted. You would be able to determine their shape, whether it is a cocci or bacillus (rod), but not the type. I'm not sure why the simple stain would be preferable unless you just wanted a quick answer as to the shape of the bacteria. In some cases, a wet prep can be made of a presumptive gram positive cocci to tell the difference between bacteria or yeast. Otherwise, I would say that the gram stain is the only way to go.
Negative staining techniques are designed to stain everything BUT the bacterial cells. This allows us to see the cells unstained and helps us observe their morphology (how the cells are shaped and how they group together). The cells have an overall negative charge on their surface, so they naturally attract positive charges. Crystal Violet carries a positive charge, so it would adhere to the surfaces of the cells thus staining the cells (which is not what you want in a negative stain!)
Safranin (red) is used in gram staining and endospore staining as the secondary stain. Nigrosin is used in negative staining, staining only the background and not the bacteria. Therefore, the bacteria within the capsule would stain red from the safranin. (Like in endospore staining and negative gram staining, safranin would stain the bacteria red.) Nigrosin would stain the background of the organism just as it would in negative staining. Bacteria (within capsul): stained safranin red Capsule (outer layer of bacteria): clear Background of organism: stained dark with Nigrosin
By doing differential stains on an unknown organism, you can learn more about that organism. One of the most helpful stains would be the Gram stain. The gram stain will differentiate from Gram positive and Gram negative cells, narrowing your bacteria down a lot. Other stains include: Acid-Fast stain, Capsule stain, Endospore stain, and PHB stain.
If the Gram Stain is completed properly, gram positive should stain purple; however, if you over decolorize a gram positive organism, the organism will appear appear pink, which is a gram negative reaction. To summarize, if you over decolorize a gram positive organism it will show as a gram negative organism.
There are two types of stains, the simple stain and the differential stain. A simple stain colors all objects the same while a differential stain is used to spot differences in microorganisms. A gram stain is a differential stain, which is used to tell the difference in gram negative and gram positive bacteria. A simple stain would stain all the organisms the same and this difference would not be noted. You would be able to determine their shape, whether it is a cocci or bacillus (rod), but not the type. I'm not sure why the simple stain would be preferable unless you just wanted a quick answer as to the shape of the bacteria. In some cases, a wet prep can be made of a presumptive gram positive cocci to tell the difference between bacteria or yeast. Otherwise, I would say that the gram stain is the only way to go.
Negative stain
A simple stain like iodine can make cell parts show up that would otherwise be nearly invisible since they are colorless.A simple stain like iodine will reveal a cell's morphology.
Negative cocci red
If you stop at this stage (without the alcohol), the Gram-negative cells will be invisible since they have lost their crystal violet stain.
# The pH will determine if the bacteria will have a particular charge. If the chromophore is a positive ion like the methylene blue in the equation shown in the reading, the stain is considered a basic stain; if it is a negative ion, it is an acidic stain. Most bacteria are stained when a basic stain permeates the cell wall and adheres by weak ionic bonds to the negative charges of the bacterial cell.
The point of the gram stain is to differentiate between two things, with out both positive and negative gram cells there would be nothing to differentiate between, defeating the purpose of the process.
A simple one would.
Negative staining techniques are designed to stain everything BUT the bacterial cells. This allows us to see the cells unstained and helps us observe their morphology (how the cells are shaped and how they group together). The cells have an overall negative charge on their surface, so they naturally attract positive charges. Crystal Violet carries a positive charge, so it would adhere to the surfaces of the cells thus staining the cells (which is not what you want in a negative stain!)
Methylene blue is a stain used in microbiology. The dye attaches to the object, which allows what would normally be fairly see-through to be visible to the microscope.
Safranin (red) is used in gram staining and endospore staining as the secondary stain. Nigrosin is used in negative staining, staining only the background and not the bacteria. Therefore, the bacteria within the capsule would stain red from the safranin. (Like in endospore staining and negative gram staining, safranin would stain the bacteria red.) Nigrosin would stain the background of the organism just as it would in negative staining. Bacteria (within capsul): stained safranin red Capsule (outer layer of bacteria): clear Background of organism: stained dark with Nigrosin
By doing differential stains on an unknown organism, you can learn more about that organism. One of the most helpful stains would be the Gram stain. The gram stain will differentiate from Gram positive and Gram negative cells, narrowing your bacteria down a lot. Other stains include: Acid-Fast stain, Capsule stain, Endospore stain, and PHB stain.