Questions and Answers
What is the purpose of a simple stain?
To visualize bacterial cell size, arrangement, and morphology.
What microscope setting is best for viewing stained specimens?
Bright field microscope.
What does a positive stain do?
Increases contrast on the bacterial image.
What is the outcome of using a negative or acidic stain?
Signup and view all the answers
In performing a negative stain with a smear, do not ___
Signup and view all the answers
What is the purpose of a wet mount?
Signup and view all the answers
What is the first step in the wet mount protocol?
Signup and view all the answers
What microscopy technique can be used with all objective lenses and is commonly used to view stained specimens?
Signup and view all the answers
_____ microscopy can be used with all objective lenses except _____.
Signup and view all the answers
_____ microscopy can be used with all objective lenses except _____.
Signup and view all the answers
Why is bright field microscopy suitable for viewing stained specimens?
Signup and view all the answers
What do dark field and phase contrast filters help to see?
Signup and view all the answers
Study Notes
Simple Staining Theory
- Simple staining enhances visualization of bacterial cell size, arrangement, and morphology by using a single dye.
- Bacterial cells are initially transparent; adding stains provides color and contrast for observation.
- Both positive and negative stains improve contrast without damaging cell structures, allowing for accurate size measurements.
- Bright field microscopy is optimal for viewing stained specimens, presenting a white background against colored cells.
Positive Basic Stain
- Positive staining increases contrast, making cells visible for observing size, morphology, and arrangement.
- Positive basic stains have a positive charge that attracts to the negatively charged interior of bacterial cells.
- Stains penetrate the cytoplasm, coloring the cell while keeping the background white under bright field microscopy.
Negative Acidic Stain
- Negative staining increases bacterial image contrast, facilitating observations of cell size and structure.
- Negative stains have a negative charge and are repelled by the cell, which remains unstained against a colored background.
- Cells appear white or transparent against the dyed background; the stain does not enter the cells.
Negative Stain Precaution
- Avoid heat fixing slides when performing a negative stain to maintain cell integrity.
Wet Mount Theory
- Wet mounts are utilized to observe living cells, particularly for motility studies.
- The procedure does not involve heat fixing, preserving the natural morphology of the bacteria.
Simple Stain Protocols
- Wet Mount: Combine one drop of water with one drop of stain, mix, apply a cover slip, and blot dry.
- Heat Fixed Smear: Prepare a smear, add a stain, wait 30-60 seconds, rinse with distilled water, blot dry, and do not use a cover slip.
Negative Stain Protocols
- Wet Mount: Add a drop of stain (no water), inoculate with bacteria, mix well, cover with a slip, and blot dry any excess.
- Smear: Drop a stain on one end of the slide, inoculate and mix, angle a clean slide to spread and create a smear, heat fix the slide, and observe under the microscope.
Wet Mount Protocol
- Start with a drop of distilled water in the center of a slide.
- Mix the sample into the water drop, cover with a slip, and blot dry if necessary before observation.
- Dispose of properly: discard cover slips in their container and place contaminated slides in a 10% bleach solution.
Bright Field Microscopy
- Bright field microscopy works with all objective lenses and is primarily used for viewing stained specimens.
Dark Field Microscopy
- Dark field microscopy is compatible with all objective lenses except bright field.
- Specimens appear white against a dark background, enhancing visibility.
Phase Contrast Microscopy
- Phase contrast microscopy is applicable with all objective lenses except bright field, enhancing the visibility of transparent specimens.
Microscopy Filter Comparison
- Bright field microscopy maintains a white background, ideal for viewing stained specimens.
- Dark field and phase contrast increase contrast, aiding in the observation of transparent or small specimens.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the theory and applications of simple staining, wet mounts, and negative stains in microbiology. This quiz will help you understand the purpose of these techniques and the optimal microscope settings for visualizing bacterial cells. Perfect for students studying microbiology or preparing for practical exams.
