Search results
Results from the WOW.Com Content Network
The epidermal layers are removed by cutting the onion and peeling them off (they are the membrane-like sheaths between each onion layer). For advanced microscopy, such as fluorescence microscopy, the layers halfway between the outside and the centre of the onion are best. Light microscopes are typically used for observing onion cells.
In smaller cells, the diffusion of molecules is more rapid, but diffusion slows as the size of the cell increases, so larger cells may need cytoplasmic streaming for efficient function. [1] The green alga genus Chara possesses some very large cells, up to 10 cm in length, [2] and cytoplasmic streaming has been studied in these large cells. [3]
Plasmolysis only occurs in extreme conditions and rarely occurs in nature. It is induced in the laboratory by immersing cells in strong saline or sugar (sucrose) solutions to cause exosmosis, often using Elodea plants or onion epidermal cells, which have colored cell sap so that the process is clearly visible.
The entire surface of the plant consists of a single layer of cells called epidermis or surface tissue. The entire surface of the plant has this outer layer of the epidermis. Hence it is also called surface tissue. Most of the epidermal cells are relatively flat. The outer and lateral walls of the cell are often thicker than the inner walls.
The onion test is a way of assessing the validity of an argument for a functional role for junk DNA. It relates to the paradox that would emerge if the majority of eukaryotic non-coding DNA were assumed to be functional and the difficulty of reconciling that assumption with the diversity in genome sizes among species. [ 1 ]
In some cases, cells may be grown directly on a slide. For samples of loose cells (as with a blood smear or a pap smear) the sample can be directly applied to a slide. For larger pieces of tissue, thin sections (slices) are made using a microtome; these slices can then be mounted and inspected.
Onions have particularly large cells that are easy to observe under low magnification. Forming a single layer of cells, the bulb epidermis is easy to separate for educational, experimental, and breeding purposes. [37] [38] Onions are therefore commonly used in science education to teach the use of a microscope for observing cell structure. [39]
The second is within the nuclei of the epidermal cells (anti-nuclear antibodies). Immunofluorescence is employed in foundational scientific investigations and clinical diagnostic endeavors, showcasing its multifaceted utility across diverse substrates, including tissue sections, cultured cell lines, or individual cells.