The alcohol is a decolorizer. In gram negative organisms, the small amount of peptidoglycan can't hold onto the crystal violet in the presence of the alcohol and so becomes decolorized. The gram positive organisms have a much thicker peptidoglycan layer, and so the crystal violet stays in even with washing by alcohol.
because an old man on the loo invented it!
to decolorize the color stain?washes away any crystal violet that is not bonded
decolorizer
The decolorizer, usually acetone or alcohol, is used to wash the Crystal Violet stain from the Gram Negative cells. From this point Safranin stain is used to stain the Gram Negative cells. The final color for Gram Negative will be a Red/Pink color.
you can omit the last step - the safranin counterstain
When performing the Gram stain, acetone is used as a wash step between the iodine and safranin. By not washing, all stains will remain crystal violet purple, and none will appear safranin red/pink.
Safranin
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.
The decolorizer, usually acetone or alcohol, is used to wash the Crystal Violet stain from the Gram Negative cells. From this point Safranin stain is used to stain the Gram Negative cells. The final color for Gram Negative will be a Red/Pink color.
The Gram stain is used for bacteria and not for viruses.
you can omit the last step - the safranin counterstain
When performing the Gram stain, acetone is used as a wash step between the iodine and safranin. By not washing, all stains will remain crystal violet purple, and none will appear safranin red/pink.
In a gram stain the primary stain is crystal violet. Iodine then sets that dye into the gram positive cells while alcohol washes out the crystal violet from the gram negative cells. Then safranin, which is the counterstain in a gram stain, is used to dye the rest of the bacteria. This is the example I can give you of why a counterstain does not change the look in all the cells. Though safranin stains all the cells, the gram positive cells that were dyed purple from crystal violet don't look pink - only the gram negative do.
Safranin
During the procedures of a gram stain, decolorization is necessary to remove any stain or color from the gram negative cells. When a dye is used to stain gram positive cells, both gram positive and gram negative cells retain color. Mordant is used to bind the original stain to gram positive cells so when decolorizer is used they retain color. After the mordant has been used a decolorizer is used to wash away colo in gram negative cells. Counterstains are used to stain gram negative cells to better visualize contrasting cells. An example of a decolorizer that works well is ethanol.
Half Answer: There are both Gram positive and Gram negative stains that are used to identify different types of Bacteria. They depend upon 'membrane content' - some stains highlight only the nuclear envelope.
A gram stain cannot detect chlamydia. A gram stain in men that finds gram negative diplococci is considered diagnostic for gonorrhea, but it can't be used in females, and it can't prove chlamydia. A gram stain in men can be used to rule out gonorrhea and possibly diagnose "non-gonococcal urethritis" if a male has symptoms. However, although it may seem that NGU is synonymous with chlamydia, there are other possible causes.
Gram stains are used to analyze bacteria and determine their characteristics. The most popular use of a gram stain is to determine the thickness of a cell wall in bacteria.
Iodine stains starch contained in cells. Iodine is also used to distinguish between Gram negative and Gram positive bacteria. The Gram stain contains iodine.
Yes, when it is used as a title.