Plasmolysis Essay

452 Words2 Pages
Materials: kitchen knife, red onions, salt, tap water, microscopic slides, cover slips Method – Obtaining a single layer of red onion cells. For this experiment, we can not use the onion skin which is found between the layers of the onion. We need a single layer of pigmented cells. These cells, however, do not separate easily. We need a thin layer of cells of the red part of the onion. It is not possible to directly cut a single cell layer, so we need to use the “peeling method” to obtain a single layer of cells. Obtain a small piece of onion about (1cm x 1cm). The onion layer is about 2mm thick. With the red side of the onion facing you, cut beneath the red layer, about half way into the onion. This cut does not have to be very thin. There will be about 1mm of onion between the knife and the red pigmented layer. Press the onion firmly against the knife with your thumb. Now tear off or peel away the red part of the onion. The red layer will become thin. Some red pigment may be released from broken cells. Cut away and discard the thick part of the onion (the place where the initial cut was placed). Observe the remaining cells (the thin, peeled part) under the microscope (using a glass slide, water and cover slip, of course. Only consider those cells that are filled with the red pigment. White cells are broken and have lost the red pigment. Method – Plasmolysis. Make a saturated solution of salt-water Using a pipette, add one drop of this solution to the specimen. The salt water should flow beneath the cover slip. There should be no need to remove the cover slip to add the salt water If there is too much water beneath the cover slip, then the salt water will not flow between the cover slip and the slide. In this case use tissue paper to withdraw water from one side of the cover slip while adding the salt solution at the other side. Observe what happens to

More about Plasmolysis Essay

Open Document