3rd December 2019
Why do we sometimes stain cells before looking at them through the microscope?
The most basic reason that cells are stained is to enhance visualization of the cell or certain cellular components under a microscope. Cells may also be stained to highlight metabolic processes or to differentiate between live and dead cells in a sample.
Why would a biologist use a stain?
Staining is an auxiliary technique used in microscopy to enhance contrast in the microscopic image. Stains and dyes are frequently used in biology and medicine to highlight structures in biological tissues for viewing, often with the aid of different microscopes.
- Take a clean cotton swab and gently scrape the inside of your mouth.
- Smear the cotton swab on the centre of the microscope slide for 2 to 3 seconds.
- Add a drop of methylene blue solution and place a coverslip on top.
- Remove any excess solution by allowing a paper towel to touch one side of the coverslip.
In a simple staining technique, a basic, cationic dye is flooded across a sample, adding color to the cells. Before we move on, let's define the word cationic. A cation is simply a positively charged ion. The molecules that make up basic dyes have a positive charge.
It consists of a lipid bilayer with embedded proteins. The basic function of the cell membrane is to protect the cell from its surroundings. The cell membrane controls the movement of substances in and out of cells and organelles. In this way, it is selectively permeable to ions and organic molecules.
Collect a drop of stain with an eye dropper or pipette. Put a drop of stain on an outer edge of your cover slide. Place a piece of napkin or paper towel against the opposite side of your cover slip, right up against the edge. This will help draw the stain under the cover and across the specimen.
Cell staining is a technique that can be used to better visualize cells and cell components under a microscope. By using different stains, one can preferentially stain certain cell components, such as a nucleus or a cell wall, or the entire cell.
1.Cell wall is found in plant cell and cell membrane is found in animal cells. 2.Cell membrane is covered by the cell wall which forms the outer most covering. 3.Cell wall is completely permeable whereas cell membrane is semi-permeable.
Methylene blue. Methylene blue is used to stain animal cells, such as human cheek cells, to make their nuclei more observable. Also used to stain the blood film and used in cytology.
Before bacteria can be stained, a smear of bacteria must be made on a slide and heat fixed. Heat fixing denatures bacterial enzymes, preventing them from digesting cell parts, which causes the cell to break, a process called autolysis. The heat also enhances the adherence of bacterial cells to the slide.
Because of its affinity for DNA and RNA, methylene blue will produce a darker stain in areas where those components are present. In the case of the human cheek cell, methylene blue causes the DNA in the nucleus to stand out so that the nucleus can clearly been seen in a light microscope.
The cheek cells that you looked at last week, and cells of every other organism except bacteria are eukaryotic. Only bacteria and cyanobacteria (also called blue-green algae) have prokaryotic cells. Prokaryotic cells differ from eukaryotic cells in that they lack a membrane- bound nucleus and organelles.
You may choose from methylene blue, Gram safranin, and Gram crystal violet. Basic stains, such as methylene blue, Gram safranin, or Gram crystal violet are useful for staining most bacteria. These stains will readily give up a hydroxide ion or accept a hydrogen ion, which leaves the stain positively charged.
Methylene blue stains the nucleic acids. Its a basic dye and bind well to DNA (negative charge). It stains the dead cells and thus differentiate it from the living cells because the dead cells will take up the stain easily than the live cells.
A counterstain, such as the weakly water soluble safranin, is added to the sample, staining it red. Since the safranin is lighter than crystal violet, it does not disrupt the purple coloration in Gram positive cells. However, the decolorized Gram negative cells are stained red.
Hematoxylin has a deep blue-purple color and stains nucleic acids by a complex, incompletely understood reaction. Eosin is pink and stains proteins nonspecifically. In a typical tissue, nuclei are stained blue, whereas the cytoplasm and extracellular matrix have varying degrees of pink staining.
Viewing specimens with a microscope: In most instances, light must pass through any object to be viewed with a light microscope. For this reason, an object to be viewed must be fairly thin. Thick objects may be sliced into thin sections for viewing.Why are they sometimes stained with dyes?
Methylene blue injection is used to treat methemoglobinemia. It works by converting methemoglobin to a more efficient type of hemoglobin to better carry oxygen throughout the body. Methylene blue oral is used to treat methemoglobinemia and urinary tract infections.
(4 points) Specimens viewed with a compound microscope must be very thin, so that light can pass through them. If they were not thin enough for light to pass through them, they would not be visible under a compound microscope.
Examples include the malachite green counterstain to the fuchsine stain in the Gimenez staining technique and the eosin counterstain to haematoxylin in the H&E stain.In Gram staining, crystal violet stains only Gram-positive bacteria, and safranin counterstain is applied which stains all cells, allowing the
The staining dye can be used to stain mitochondria in both live cells and fixed cells. Live cells stained with the dye may be fixed with formaldehyde. MitoRed is a far-red fluorescent mitochondrial dye (Ex/Em=622/648 nm). The staining is dependent on mitochondrial membrane potential.
This smaller sheet of glass, called a cover slip or cover glass, is usually between 18 and 25 mm on a side. The cover glass serves two purposes: (1) it protects the microscope's objective lens from contacting the specimen, and (2) it creates an even thickness (in wet mounts) for viewing.