Lab 3.4: simple stains Flashcards
Bacterial cells are much ?? than eukaryotic cells and come in a variety of ?? and ??
-smaller
-morphologies (shapes)
-arrangements
What is the first step in identifying a bacterial species?
-determining cell morphology
chromophore:
-portion of the chromogen that gives it its color
Basic stains:
-positively charged chromogen
-are attracted to the negative charges on the surface of most bacterial cells (ionic bond), colorizing the cell
Common basic stains:
-methylene blue (stain for 30 to 60 seconds)
-crystal violet (stain for 1 minute)
-safranin (stain for 30 to 60 seconds)
Basic stains are applied to bacterial smears that have been ??
-heat fixed
What does heat fixing do?
-kills the bacteria
-makes bacteria adhere to the slide
-coagulates cytoplasmic proteins to make them more visible
What is the purpose of heat-fixing bacterial smears before applying a simple stain?
To improve the adhesion of cells to the slide
What role does the chromogen play in a staining solution?
-provide color to the specimen
What is the term for the process of fixing cells to a slide before staining?
-heat fixing
What is the typical procedure for a simple stain?
-using a single dye to color all cells uniformly
What is the primary reason basic stains are attracted to bacterial cells?
-Ionic bond with negative charges on the cell surface
Which part of a stain solution is responsible for providing color to the specimen?
-chromogen
What component of bacterial cells is commonly stained by a simple stain?
-cell wall
Which bacterial structure is not typically visible with a simple stain?
-flagella
