Lab 3 Notes.docx - Negative Stain(Ex 6 Smear Preparation...

Info icon This preview shows pages 1–2. Sign up to view the full content.

Negative Stain (Ex. 6) & Smear Preparation and Simple Stain (Ex. 7) I. Background -The purpose of utilizing stains (dyes) is to increase contrast and improve our ability to see their morphology and arrangement. -Stains consist of: 1) Solvent - (water or ethanol) 2) Chromogen - colored molecule (benzene derivative) 3) Chromophore - portion of the chromogen that gives it its color 4) Auxochrome - charged portion of a chromogen -Positive - (basic or cationic dyes) -Negative - (acidic or anionic dyes) -Negative Stains- are most ideal for determining the size, morphology, and arrangement of bacterial cells because they are not heat fixed which causes distortion. Type of Stain Alternative Name Examples Purpose Procedure Negative (-) Acidic or Anionic dye Nigrosin , Eosin, or India ink -Most ideal for determining cell size , morphology and arrangement . -Stains background only!!! Draw : Unstained Transparent cell (negative) + Nigrosin (negative)= stained background- due to repulsion between cell and acidic dye 1)Preparing a smear 2)Air drying smear 3)Staining the smear *No Heat-Fixing Step Basic (+) Cationic dye 1)Methylene Blue 2)Crystal Violet 3)Safranin -Simple stain is used to make cells more visible under microscope. -The actual cell is stained, not the background!!!
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern