2.1.1: Staining In Microscopy Flashcards
What is differential staining?
A technique that uses multiple chemical stains to color different parts of a cell in various colors.
What are two commonly used stains in light microscopy?
Crystal violet and methylene blue.
What charge do crystal violet and methylene blue have?
They are positively charged and stain negatively charged materials.
What are nigrosin and Congo red?
Negatively charged stains that cannot enter cells due to cytosol repelling them, creating a stained background.
What is Gram staining?
A method to visualize different bacteria using two stains: crystal violet and safranin.
What is the appearance of Gram-positive bacteria after staining?
They appear blue/purple due to the retention of the crystal violet stain.
Why do Gram-negative bacteria appear red?
They do not retain crystal violet stain due to their thinner peptidoglycan cell wall and are counterstained with safranin.
Why is distinguishing between Gram-positive and Gram-negative bacteria important?
It helps medics prescribe appropriate antibiotics, such as penicillin for Gram-positive bacteria.
