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Why use a loop full of water and not a large drop of water on a bacterial smear slide?
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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.
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
How do you prepare a canine ear exudate cytology slide?
Using a sterile cotton swab, gently remove some of the exudate from the dog's ear. Place the exudate on a glass microscope slide and, pressing firmly, smear the exudate across the slide. Use an open flame source (hand-held flick-style cigarette lighters work well) and gently head the underside of the slide to attach the exudate to the slide. Stain the slide with standard Gram stain following the manufacturer's directions. Rinse the slide gentle with tap water and then place on the microscope for viewing.
What is the technique for gram staining test?
the gram staining procedure involves four basic steps; 1.the smear is first flooded wit the primary stain crystal violet dye.in this case the primary stain is the first dye applied in any multicelled staining procedure and it stains all the cells. 2.the smear is rinsed with water to remove any excess crystal violet and then its flooded wit a dilute solution of iodine called grams iodine.iodine acts as a mordant.i.e. the substance that increases the interaction and affinity of cellular components for a dye.this is done so that the cells can stain more strongly. in this case the iodine complex thereby decreases the solubility of the dye within the cells 3.the stained smear is rinsed again and then 95% alcohol or a mixture of alcohol and acetol is briefly added.this solvent acts as decolorizing agents and they readily remove the dye iodine complex from gram negative but not from gram positive bacteria. 4.a counter stain is then applied to import a contrasting color to the now colorless gram negative bacteria.for this purpose,the red dye safrannin is used.this dye stains gram negative as well as gram positive bacteria but because the gram positive are already stained purple,it impacts little difference
What happens if you add too much water to a smear slide?
The slide can get damaged.
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 happens when you prepare a smear from a agar plate or slant without first placing water on slide?
If you prepare a slide from an agar plate without placing water on the slide first the agar will be to lumpy on the slide. It will make to much of the specimen be in one spot.
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.
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 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.
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?
To avoid denaturing and destroying the smear.
Why is it necessary to excessively rinse the smear with water in experiment identifying bacteria using gram stain?
smear should be rinsed with distill water so that all the small particles attach to the smear will washed away such as some time the crystals of dye are attached to the smear which give the illusion of microbial cell some time, distill water is used because it is free from other microbial cell and ions which can harm the smear.
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 smear preparation?
A smear preparation is a techniques that is used as a precursor is many different staining techniques.The smear prep usually calls for the sample bacterium to be placed on a microscope slide (use aseptic technique) with one drop of DI water. Then the slide is allowed to air dry for a few minutes then the slide is passed through a Bunsen burner flame. Use a cloths pin so that you do not burn you hands Only pass the glass microscope slide through the flame not you cloths pin if it is wood it will catch fire. Pass the slide through 3-4 times then you are ready to continue on with your desired staining technique
