Gram stain Staining techniques are used to observe form, shape and size of bacte
ID: 151893 • Letter: G
Question
Gram stain Staining techniques are used to observe form, shape and size of bacteria - all important criteria in their study. Simple stains dye normally colorless bacteria so they may be observed microscopically. All bacteria will be the same color when a simple stain technique is used. The Gram stain technique is a differential stain involving a multi-step process. It is one of the most important laboratory procedures in microbiology, and is often the first step in identification of unknown bacteria. The gram stain was developed in the 1800's by Hans Christian Gram. The technique divides bacteria into two groups based on their ability to retain the purple colored primary stain, crystal violet. Gram positive bacteria have a thicker layer of peptidoglycan in their cell wall which traps the crystal violet. lodine is a mordant that helps to entrap the primary stain in the cell wall. Alcohol is used to decolorize, or remove the crystal violet from the gram negative cells that do not have as much peptidoglycan in the cell wall, but it does not remove the crystal violet from gram positive cells. The decolorizing step is critical to a successful gram stain. The last step in the gram stain technique is to add a counterstain, safranin, which dyes the gram negative cells red.Explanation / Answer
1. Staining techniques are used to observe form, shape and size of the bacteria- all important criteria in their study. Simple stains dye normally colorless bacteria so they may be observed microscopically.All the bacteria will be the same color when a simple stain technique is used.
2. No changes can be seen
3. Mordant helps to entrap the primary stain the cell wall.
4. Because gram positive bacteria cells have prptidoglycan so it retain the primary stain.
5. In a gram stain test, bacteria are washed with a decolorizing solution after bring dyed with crystal violet. On adding a counterstain such as safranin or guchsine after washing, gram negative bacteria are stained red or pink while gram positive bacteria retain thin crystal violet dye.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.