Staining Techniques in Microbiology

Why is staining useful when viewing microbes under a microscope?

• Staining allows the scientist to better visualize the environment behind the microbe.

• Staining allows the scientist to increase the magnification of the microscope.

• Staining allows the scientist to better visualize microbes which are usually colorless and transparent.

Gram-Staining is what type of staining technique?

• A special staining technique.

• A differential staining technique.

• A simple staining technique

• A fluorescent staining technique.

There are two major types of simple stains used to better visualize microorganisms. What are these two types of simple stains and how do they differ?

• Basic stain is a positively charged dye; Acidic stain is a neutral dye.

• Basic stain is a positively charged dye; Acidic stain is a negatively charged dye.

• 
  Basic stain is an indirect stain; Acidic stain is a direct stain.

Simple staining is a procedure often used to increase the contrast of _____________ microscopes.

• Fluorescence microscopes.

• Compound light (brightfield) microscopes.

• Dark-field microscopes.

• Transmission electron microscopes.

Which of the following statements is true?

• A basic dye is negatively charged & stains the outside of a cell while an acidic dye is positively charged & stains the inside of a cell.

• A basic dye is positively charged & stains the outside of a cell while an acidic dye is negatively charged & stains the inside of a cell.

• A basic dye is negatively charged & stains the inside of a cell while an acidic dye is negatively charged & stains the outside of a cell.

• A basic dye is positively charged & stains the inside of a cell while an acidic dye is negatively charged & stains the outside of a cell.

A scientist is examining more than one species of bacteria under a microscope at the same time. The scientist decides to differentiate the bacterial cells based on their cell wall/cell envelope structure. Which staining technique should she use?

• Gram-staining.

• Basic staining.

• Envelope staining.

• None of the above.

A scientist has a sample containing a variety of different bacteria species. She wishes to identify which bacteria in her sample are of the genus Mycobacterium. Mycobacterium have a wax-like, nearly impermeable cell wall which contains mycolic acid. Which type of staining technique should the scientist use to identify the Mycobacterium?

• Basic staining.

• Gram-staining.

• Mycolic staining.

• Acid-fast staining.

Which of these is considered a special stain that correctly matches its description?

• Endospore stain:stains the capsules of bacteria found in the human eye.

• Gram-stain:used to differentiate gram-negative from gram-positive bacteria.

• Acid-fast stain:identifies acid-fast bacteria that contain mycolic acid in their cell walls.

• 
  Flagella stain:stains the flagellum of bacteria like Bacillus cereus.

What is the major difference between special staining techniques and differential staining techniques?

• Special staining stains the background behind the specimen. Differential staining stains the specimen

• Special staining stains specific structures of a cell. Differential staining differentiates different type of specimens.S

• Special staining differentiates gram + from gram – cells. Differential staining stains capsules and flagella.

_______ is/are used to attach fluorochrome molecules to antigens on the surface of bacterial cells in immunofluorescence.

• DNA

• Ribosomes

• Antibodies

• Flagella