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    Introduction to Light Microscopy: The Compound Microcope

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    I. Microscope Components:
    a. Binocular eyepiece tube
    b. Revolving Nose piece
    c. Arm and Base
    d. Stage and its associated parts
    i. Movable slide clamp
    ii. Stage motion controls
    II. Optical Components
    a. Light source
    b. The condenser
    c. Objective lenses
    d. Resolving power
    e. Depth of field
    f. Parfocality
    g. Working Distance
    h. Ocular Lenses

    1. What is the purpose of the condenser?
    2. What is the function of the objective lens?
    3. What is the relationship between the numerical aperture and the resolving power?
    4. What is the total magnification of the microscope when the 10X objective len is used?
    5. Working Distance of the objective lenses is the distance between the tip of that objective and the speciment being viewed. Based on these information, which objective lenses give you the longest working distance ?
    6. Why is the microscope called the compound microscope?
    7. What are two methods to increase contrast to a specimen?
    8. What structure in the cell does Acetocarmine binds to and stain it red?
    9. What structure in the potatoe does potassium iodide I2KI binds to?
    10. What structures in the cell does Toluidine Blue binds to?

    © BrainMass Inc. brainmass.com December 24, 2021, 11:26 pm ad1c9bdddf
    https://brainmass.com/biology/biotechnology/introduction-light-microscopy-compound-microcope-569217

    SOLUTION This solution is FREE courtesy of BrainMass!

    1. What is the purpose of the condenser?
    The function of the condenser lens is to focus the maximum amount of light from the light source upon the specimen. The condenser must focused a small and bright focused spot for the best result.

    2. What is the function of the objective lens?
    The function of the objective lens is to to accomplish the first stage of magnification in the compound microscope

    3. Define numerical aperture ( NA) ?
    The numerical aperture is a measure of the light gathering capacity of the objective lens. The greater the value of NA, the greater the resolving power.

    4. What is the total magnification of the microscope when the 10X objective len is used?

    Ocular lens ( 10X) X 10X = 100X

    Since the ocular lens magnifies the image formed by the objective lens ten times, the value for each objective lens magnification times the 10X magnification for the combined compound system.

    5. Working Distance of the objective lenses is the distance between the tip of that objective and the speciment being viewed. Based on these information, which objective lenses give you the longest working distance ?
    Working distance for a focused objective is the distance between the tip of that objective and the specimen being viewed. Working distance varies greatly between objectives. Working distance decreases with an increase in the power of the objective. A high power objective (100X) has a short working distances. A low power (4X) objective has a long working distance which eliminate the needs to lower the stage.

    6. Why is the microscope called the compound microscope?
    The microscope has two lenses: the ocular lenses use the real image formed by the objective lens as its object and produces the virtual image that the viewer sees. The reason the microscope is called a compound microscope is because the image the viewer sees is formed by two lenses in optical series.

    7. What are two methods to increase contrast to a specimen?

    Contrast relates to the ability of the viewer to distinguish an object from its background. Two methods to increase contrast are partial closure of the condenser diaphragm and differential staining. When the condenser diaphragm is wide open, it is difficult to see much detail. However, if you slowly close the condenser diaphragm, you should see more detail of your specimens.
    Differential staining involves the use of stains (dyes) that bind to various components of the speciment to increase contrast. The stains bind to particular substances in cells or tissues.
    There are three different stains with three different binding affinities

    Acetocarmine - This natural stain that comes from an insect binds to chromatin and stains it red. It is useful in identifying nuclei.

    I2KI- This stain is a mix of iodine (I2) and potassium iodide ( KI). I2KI form a chemical reaction between iodine and starch granules of green plants. The resulting starch-iodine complex has deep purple color

    Toluidine Blue. This stain bind to different cellular components, the color produced may be different and dependent upon chemical composition of that component.

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    © BrainMass Inc. brainmass.com December 24, 2021, 11:26 pm ad1c9bdddf>
    https://brainmass.com/biology/biotechnology/introduction-light-microscopy-compound-microcope-569217

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