0
Why use a loop full of water and not a large drop of water on a bacterial smear slide?
Using a loop full of water instead of a large drop of water on a bacterial smear slide allows for better dispersion and even distribution of the bacterial sample. A loop full provides a more controlled and manageable volume, preventing excess water that could dilute the sample or lead to uneven spreading. This ensures clearer observation of individual bacterial cells under the microscope, facilitating accurate identification and analysis.
What else can I help you with?
What is meant by heat fixing a bacterial smear?
to allow the excess water to dry out before heating. if heated right after, the water would cause the smear to overheat and denature some features in the stain. and those features would no longer be seen
What precautions are important when a prepared slide is observed under the microscope?
Microscopes work on the principle of magnifying light rays passing through a tiny object. The object should be transparent or translucent and colored to be properly viewed under a compound microscope. Some of the mandatory requirements to prepare a good slide for viewing are as follows: Before creating a smear, always check that the slide is clean and perfectly transparent. It should also be microbe free. So, take a slide and wash it first with soap-water, and then wipe it with ethanol (ethyl alcohol). This makes the slide clean and sterilized. With regard to preparing a slide of bacterial specimen, when you create a smear, do not make a thick layer of smear. Take very little quantity of the inoculum. If by chance you take too much of the inoculum, spread it over the slide to a larger area, such as to avoid a thick smear. Air drying is necessary, as it lets the bacteria congregate at their places. Heat fix the slide with precision. Too much heat fix can kill the organism, and too little of it will make the organisms too loosely bound to the slide surface. If they are loosely bound, they will fall off when you flood the slide with stain. One good way of identifying the extent of heat fix is to feel it after you pass the slide through the flame. It should neither be too hot nor warm. It should give you the sense of heat but tolerable. When you stain the slide, do not stain the whole surface of the slide. This wastes much of the stain and is messy. Cleanliness is very important in all science experiments. Just staining the area containing the smear is enough. Usually, stainings are done for a minute or two, but for certain experiments like endospore staining, the extent of staining time may be as long as 10 mins or even more. During such cases, ensure that the stain does not dry over the smear. Maintain liquidity of the stain, as it is to be washed after some time. While washing the slide after staining, do not let the water stream fall directly on the smear. This may disrupt the smear. Let the stream of water flow slowly along the surface, such that only the stain is flooded and the smear is intact. While preparing fungal slides, take the stain first, and then the hyphal fragments. Crush the hyphal fragments properly by placing a coverslip over the fragments (avoiding air bubbles) and the slowly tapping it with the butt of a pencil. Always observe under 10X first. This will give you an idea of the location of a good area for observation. After this, you may prefer to switch over to 45X. 100X objective in compound microscopes is always used as an oil-immersion objective, so do not ever observe at a specimen at 100X without oil.
Why use water in gram stains?
Water is used in Gram stains primarily to rinse and remove excess dye and other reagents from the bacterial smear. This helps to ensure that the staining process highlights the differences between Gram-positive and Gram-negative bacteria, as the water aids in the clarity of the final results. Additionally, it helps to prevent background staining, allowing for better visualization of the bacterial cells under a microscope.
How can incorrect results with Gram-variable can be avoided?
Run a positive and negative control organism on the same slide with the unknown Make a thin smear Pay close attention when decolorizing and rinse with water as soon as bleeding stops
What is the steps for performing a cheek cell (buccal) in the correct order?
To perform a cheek cell (buccal) smear, start by rinsing your mouth with water and spitting it out to remove debris. Next, use a sterile swab to gently scrape the inside of your cheek to collect epithelial cells. Then, smear the collected cells onto a glass microscope slide to create a thin layer. Finally, allow the slide to air dry, and optionally, fix and stain the sample for microscopic examination.
What happens when you prepare a smear from a agar plate or slant without first placing water on slide?
If you prepare a smear from an agar plate or slant without first placing water on the slide, the cells may not adhere well to the slide, leading to uneven distribution and difficulty in visualization. Adding a drop of water before preparing the smear helps the cells adhere to the slide and spread evenly for better microscopic examination.
What happens if you add too much water to a smear slide?
Adding too much water to a smear slide can cause the sample to become diluted, making it difficult to accurately visualize and identify cells under the microscope. The excess water can also cause the sample to spread unevenly on the slide, leading to distorted or unclear images.
Should you always use sterilized water for smear preparation?
Yes, when you are performing smear preparation, you should always use sterilized water. This will ensure that nothing contaminates your slide.
What is meant by heat fixing a bacterial smear?
to allow the excess water to dry out before heating. if heated right after, the water would cause the smear to overheat and denature some features in the stain. and those features would no longer be seen
What would be observed in the blood smear of patient who has malaria?
sBoth thick and thin blood smears are taken from the finger tip of earlobe of malaria patient. This smear is kept in water to dissolve and remove the haemoglobin from the slide. The slide is stained and visualised under oil immersion lens to see the malaria parasites directly.
Why tap water is used for smear washing in staining?
Tap water is used to wash the excess stain from a slide prepared from a smear. You can use tap water instead of distilled water because you aren't worried about a precipitate forming and tap water is much cheaper than distilled.
What bacterial staining technique is used when water is used to remove excess stain from the slide?
simple
Why do you air-dry a smear?
Air-drying a smear helps to fix the cells onto the slide, preventing any loss or distortion during further processing steps like staining or examination under a microscope. It also helps to evaporate any excess water, improving the visualization of the cells.
Why is there need to fix the bacteria to the slide?
To heat fix a bacterial smear you would put the specimen on the slide and either put slide on a slide warmer or over a Bunsen burner for a few seconds. Heat fixing a bacterial smear does kill the specimen but it makes the bacteria stick the slide to withstand the rinsing process.
Is presence of grease or dirt on a glass slide going to result in poor smear preparation?
The smear will not adhere well if there is grease on the slide.
What is the procedural difference between using broth and agar as a source of bacteria for preparing a smear?
If your colonies were grown in broth, you can simply use your loop to collect loopfuls of liquid medium and smear that onto a glass slide. If they were grown on an agar plate you would have to add a few drops of water to the surface of the glass slide.
What is the purpose of simple staining procedure?
In simple staining the bacterial smear stained with single dye or reagent which bring the distinctive contrast between organism and its background. PROCEDURE: 1 Prepare bacterial smear by placing loopfull culture of bacteria on slide. 2 Allow the slide to dry and heat fix it over flame. Do not heat extreamly, it can demage the shape or structure of bacteria. 3 Now flood the smear with methylene blue for 1-2 minutes. 4 Gently wash the smear with distill water to remove excess stain and dry it slowly with tissue paper. 5 Examine the slide in 100x or oil-immersion for the morphology of bacteria.
