5 Questions
What is the composition of basic dyes used for bacterial staining?
Colored positive ions
What is the purpose of passing the slide through a Bunsen burner flame during smear preparation?
To heat-kill and fix the organisms to the slide
Which type of stain is used for negative staining in bacterial samples?
Acidic dye
What is the purpose of spreading the organisms over an area about ⅔ of the slide during smear preparation?
To ensure even distribution of bacteria for staining
Which type of stain consists of both colored negative and positive ions?
Neutral dye
Study Notes
Basic Dyes
- Basic dyes, used for bacterial staining, are composed of a colored positive ion (chromophore) and a negative ion (counter ion).
Smear Preparation
- Passing the slide through a Bunsen burner flame during smear preparation is done to fix the bacterial cells to the slide, killing them and preventing them from being washed away during the staining process.
- Spreading the organisms over an area about ⅔ of the slide during smear preparation helps to achieve a uniform single layer of bacteria, which is essential for accurate staining and microscopic observation.
Staining Techniques
- Negative staining in bacterial samples is achieved using nigrosin or India ink, which allows the bacteria to appear as unstained objects against a dark background.
- Stains that consist of both colored negative and positive ions are called acid-base indicators.
Test your knowledge of bacterial staining with questions about the composition and types of stains, smear preparation, and staining techniques. Learn about the importance of staining in making bacteria visible under a microscope.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
