Electron Microscope Essay

Concept 6.1 Biologists use microscopes and the tools of biochemistry to study cells 1. The study of cells has been limited by their small size, and so they were not seen and described until 1665, when Robert Hooke first looked at dead cells from an oak tree. His contemporary, Anton van Leeuwenhoek, crafted lenses and with the improvements in optical aids, a new world was opened. Magnification and resolving power limit what can be seen. Explain the difference. Magnification is the ratio of an object’s image size to its real size. Resolution is a measure of the clarity of the image; it is the minimum distance two points can be separated and still be distinguished

One of J.J. Thomson's most significant contributions to science, and thus to the study of atomic theory, was his discovery of the electron. Before the discovery of the electron, the atom was already associated with having electric charges-both positive and negative-but the idea of an electron existing as its own particle was unheard of. It was in 1897 when Thomson first conducted the beginning of his now famous experiment, in which he used a cathode ray tube to aid in his findings. A cathode ray tube, is a vacuum tube in which cathode rays, negatively charged particles, are produced at the cathode and travel through the vacuum, which is created when gas is extracted from the tube. J.J. Thomson discovered that in order to determine

Preparing specimen for electron microscope hard, light microscope still very useful as a window on living cells.

The illuminating parts of a microscope enable us to see the detail of the subject placed under the microscope. The three main parts that enable us to do this are: the condenser which illuminates the object that is placed under the microscope, the objectives which forms the magnified image, and the eyepiece which enables us to see the magnified

1895 – X-rays were discovered accidentally by physicist Wilhelm Conrad Rontgen. Rontgen was working on a experiment and testing whether cathode rays could pass through glass. He noticed that a nearby tube emitted fluorescent glow of crystals. The air in the tube was released, high voltage applied, the same tube emitted a fluorescent glow. When Rontgen covered the tube in a heavy black paper, a green light could be seen. He concluded that a new light ray was being broadcast. Rontgen discovered that the light was very powerful and the same ray could pass through human tissue, but not through bones and metal objects. Medical applications were soon to follow. ("History of radiography," )

In electron microscopy, on the other hand, a beam of electrons with a negative charge, instead of light is sent through a very thin slice of the specimen.  Because the electron beam has a far smaller wavelength than light used in light microscopy, it achieves far better resolution, “the current resolution of limit of the best electron microscope is approximately 0.05 nm atomic resolution, and 4000X better magnification than that of a conventional light microscope”(BSP, S., 2010).  This means that with an electron microscope you can potentially achieve enough magnification to observe the shape of the protein machinery that carries out the work inside of cells. The major limitation of electron microscopy is that specimen

It was then during the 1950’s that Zacharias Jansen and his father, Han Jansen, created the first high-powered compound light microscope. Images could be magnified up to 9x which was a novel feat at that time. Zacharias and his father created the device after experimenting with glasses and discovered that by placing multiple lens in a tube they could increase magnification. Unfortunately, the microscope lacked the high resolution we have come to expect in modern-day light microscopes. The images produced by the Hans’ primitive microscope was extremely blurry and had limited

By using their microscopes, they found that every living plant and animal they examined was made of cells. As microscopes were improved, scientists were able to see smaller and smaller organisms. They found that no matter how large or small the organism was, it was made of cells, leading to cell theory. For example, a German biologist, Theodor Schwann discovered that all plant and animal cells were divided into cells by looking through his microscope. He also discovered that the cell is the basic unit of organization in organisms. Cells can be grouped together to form tissues, which can in turn be grouped together to make an organ. Organs can be grouped together to form a system, which is part of an organism. He was able to use microscopes to see the ways that cells work and help to determine which kind of microorganisms (bacteria) is causing the disease and making people ill. This is particularly valuable in the study of the components of organisms, where physicians are able to overcome a treatment of method to kill disease cells and restore people¡¦s health. The microscope revealed not only the cellular structure of human tissues, but also the organisms that cause diseases. The discovery of cells led scientists to study cells and discover more information about cells; this, allowed scientists to find ways to prevent or cure diseases. The use of microscopes has made many

During an experiment he placed his hand between the source of the X-ray, the cathode-ray tube and a screen and saw the faint outline of the bones of his hand. It was the first X-ray picture. The more dense bone absorbed more X-rays then the less dense flesh producing an image of his hand. He soon learned that photographic plates were sensitive to X-ray as they are to light and was thus able to make the first X-ray photography. These first "Roentgen exposures" were of various metal objects that were locked in a wooden case and of his wife's hand.

Many important scientists contributed to the development of the microscope, however, perhaps the most influential is Anton van Leeuwenhoek. Known as the father of microbiology, Van Leeuwenhoek was the first to discover bacteria through the use of microscopes that he developed himself (2, 3). Since then, many more scientists have made other changes leading to even more advancements in microscopy. Some of the microscopes most commonly used in microbiology include bright field, dark-field, phase-contrast, fluorescence, and differential interference contrast (DIC) microscopy (1). For this particular report, bright-field microscopes are used to visualize the unknown bacteria. Microorganisms are able to be viewed using the contrast of the microbe against the bright background of the slide (1). Sometimes it can be difficult to view microbes against a light background because they will seem transparent or have little contrast. To increase the contrast and allow for easier viewing, microbes are often stained. A condenser allows visible light to be focused and create a contrast between the background and the specimen. The microscope contains 4x, 10x, 40x, and 100x objective lenses. The 4x and 10x are used in order to scan the slide and determine the general location of the stained bacteria while the higher magnification lenses are

The X-Ray was invented in 1895 by Wilhelm Conrad Roentgen. It all started with a vacuum tube called a Crookes tube, with this Roentgen noticed that by pressing a button that activated an electric current through it a shadow was projected onto a screen that showed the photograph of his wife’s hand with a ring

Focus is related to focal length and can be controlled with the focus knobs. The thickness of the cover glass on the specimen slide can also affect the ability to focus the image if it is too thick for the objective lens. The correct thickness is usually written on the side of the objective lens.

During the cold winter of 1895, a German scientist by the name of Wilhelm Conrad Roentgen was working with a cathode-ray tube when he noticed nearby crystals were glowing. When Roentgen reached for the crystals he was amazed when the shadow cast on the crystal was not of his whole hand, but just his bones. Roentgen covered the tube with heavy black paper and saw that the crystals still glowed and the shadow of his hand bones still shown through, he then determined that a new ray was being emitted that could penetrate through thick materials. (1.) He later found that the rays could pass through most anything, but would cast a shadow of solid objects; these shadows could then be captured on film. Among the solid objects Roentgen shot with

NOTE: Answer Question A only if you used a compound light microscope for this experiment.

“The prefix ‘nano’ stems from the ancient Greek word for ‘dwarf’. In science, it means one billionth (10 to the minus 9) of something, thus a nanometer (nm) is one billionth of a meter, or 0.000000001 meters. A nanometer is about three to five atoms wide, or some 40,000 times smaller than the thickness of human hair. A virus is typically 100 nm in size.” (Paddock) “The ability to manipulate structures and properties at the nanoscale in medicine is like having a sub-microscopic lab bench on which you can handle cell components, viruses or pieces of DNA, using a range of tiny tools, robots and tubes.” (Paddock) There is one type of microscope in the world that has the ability to see things at the nano scale. That microscope is a scanning tunneling microscope. It has the ability to zoom in on an object by 1,000,000 times as the average high school and college microscope only reaches 100(Nano.gov).