University:
California State University, Northridge
Course:
BIOL 101 | General Biology
Academic year:

2022
Views:

154

Pages:

2
Author:

B. Coleman

TECHNIQUES FOR STUDYING CELLS: Microscopes The development of cells began with the observation of living objects using a microscope by scientist Anthony van Leeuwenhoek (1632-1723), who studied microscopic organisms such as Protozoa and Rotifera which were given the name "animanculus", various types of bacteria, including bacilli and spiral bacteria; observed sperm in humans, frogs, dogs, and fish. Apart from that, it also affects the movement of blood cells in the capillaries of frog legs and rabbit earlobes. Research on cells continued to develop as the main supporting tools for microscopes began to improve, from light microscopes (LM) to electron-based microscopes in the early 1950s, which further developed with the discovery of the electron microscope. Two types of microscopes that are very important are transmission electron microscopes (TEM) and scanning electron microscopes (SEM). An electron microscope focuses a beam of electrons through the specimen under observation instead of visible light. TEM uses an electromagnet as a lens to focus and magnify images by bending the path of electrons. The image formed is finally focused on the screen so that it can be seen or focused on photographic film. TEM is a microscope that is mainly used to study the internal ultrastructure of cells. SEM, like TEM, also functions to see the surface of a specimen in detail, where the electron beam will shine on the surface of the sample which is usually coated with a thin gold film. SEM has a large depth of field so it produces images that appear three-dimensional. Electron microscopes have the advantage of observing parts that cannot be seen with ordinary light microscopes. However, the weakness of an electron microscope is that it can only observe dead cell specimens, and it produces artifacts that are not actually found in living cells. Meanwhile, a light microscope has the advantage of being able to observe living cells even at a lower magnification than an electron microscope. Observation using a microscope is basically the principle of visualization of the object being observed, in this case cells. The most important thing is how well the microscope uses various techniques to be able to separate the parts that need to be observed from the cell (resolution or resolving power). Therefore, in order to separate parts of an object and increase resolution power, several techniques can be used, such as contrast coloring of the part to be observed and appropriate lighting. The staining process is also a very important technique in observing cells and their organelles. With certain techniques the staining process will be able to show cells and their parts. The use of a microscope is essential for observing cytology as a very basic study of cell structure. In its development, cytology was not enough to study the complexity of cells, so it continued to develop into new branches of Biology such as Cell Biology and also Molecular Biology. The microscopic size of cells is a limitation in observing cells.