Introduction to Staining & Bacterial Cell Morphology

These flashcards cover key vocabulary related to staining techniques and bacterial morphology, as discussed in the lab.

Staining

A technique used to increase the contrast between microorganisms and the background.

Bacterial shapes

Common shapes of bacteria include bacilli (rods), cocci (spheres), and spirilla (spirals).

Negative Staining

A staining technique where acidic stains color the background instead of the cell, preserving delicate structures.

Chromophore

The part of a dye that gives it color.

Auxochrome

The positively or negatively charged group in a dye that helps it to bind to cell components.

Bacilli

Rod-shaped bacteria.

Cocci

Spherical-shaped bacteria.

Spirilla

Spiral-shaped bacteria.

Heat Fixing

A procedure used to attach cells to a slide, but it can distort delicate cells.

Simple Stains

Stains that use basic or acidic dyes to color microorganisms for contrast.

Smear Preparation

A method to spread a sample on a slide to create a thin film for observation.

Staining Process Steps

1. Make a smear 2. Stain cells 3. Wash excess stain 4. View under microscope.

Crystal Violet

A basic dye used in simple staining procedures, requiring 30-60 seconds of exposure.

Methylene Blue

Another basic dye used in staining, requiring 30-60 seconds of exposure.

Safranin

A basic dye used in simple staining, can be left on for up to 1 minute.

Pure Culture

A culture containing only a single type of microorganism.

Bacterial Arrangements

The arrangement of bacterial cells can be single, diplo (pairs), strepto (chains), or staphylo (clusters).

Smear from a Colony

Preparing a slide by selecting a small amount of bacteria from an agar plate.

Purpose of Staining

To highlight differences between microorganisms, including cell shape, arrangement, and structural features.

Negatively Charged Auxochrome

Part of acidic stains that binds to positively charged proteins in cells.