18 Questions
Describe the steps involved in negative staining.
Flood the slide with acid-alcohol, drain the excess, and allow it to air dry.
What is the purpose of negative staining?
To study the shape, size, and arrangement of bacteria cells that are difficult to stain.
What is one of the commonly used negative stains?
Sodium (potassium) phosphotungstate (PTA).
Who developed the acid-fast staining technique?
Ziehl and later modified by Neelsen.
What is the main aim of acid-fast staining?
To differentiate bacteria into acid-fast and non-acid-fast groups.
Why is acid-fast staining necessary for certain microorganisms?
Because they are not staining by simple or Gram staining methods.
What is the purpose of negative staining in microscopy?
To contrast a thin specimen with a fluid
How does negative staining prevent dye from penetrating bacterial cells?
The stain's negative charge repels the negative charge on the bacteria's surface
Why do bacteria remain unstained in negative staining?
The negative charge of the stain repels against the bacteria's surface
What is the main characteristic of the stain used in negative staining?
It has a negative charge
In negative staining, how does the specimen appear against the background?
The specimen appears unstained against a colored background
When is negative staining often used in microscopy?
In diagnostic microscopy
What is the purpose of negative staining in microbiology?
To enhance and contrast a biological specimen at the microscopic level.
How does negative staining differ from conventional staining methods?
Negative staining enhances the background around the specimen, while conventional staining enhances the specimen itself.
What is the primary purpose of Gram staining in microbiology?
To differentiate bacteria into two groups based on their cell wall composition.
What are the steps involved in the Gram stain procedure?
Applying a primary stain (crystal violet), adding a mordant (Gram's iodine), rapid decolorization with ethanol or acetone, and counterstaining with safranin.
How does the Gram stain procedure help in the diagnosis of bacterial and fungal infections?
It provides a simple and inexpensive method for rapid diagnosis by categorizing bacteria as Gram-positive or Gram-negative.
Why is negative staining considered an important technique in microbiology?
It allows for enhanced visualization of biological specimens at the microscopic level.
Learn how to perform a negative staining technique in microbiology to study bacteria cells that are difficult to stain or too delicate to be heat-fixed. Explore the steps involved, such as flooding the slide with acid-alcohol and using sodium phosphotungstate as a common negative stain.
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