General Microbiology

Keiser University Online Microbiology I Virtual Lab 1 Worksheet Microscopy & Gram Staining Name: _________ 1. For each of the 4 microscopes below, list some items that you would be able to view with that particular type of microscope. Compound Light : Tissue Samples, Blood and Microscopic Cells SEM : The details of a specimens surface Dissecting Scope : Organs, Tissue, Leaves, Stems and Mold TEM : Internal structures of a cell 2. For the letter “e”, draw or describe what it looked like under the objectives below: 4X 10X 40X 3. After you become familiar with the microscope and view the slides, then try your hand at the puzzles and measuring exercises. How did you adjust the scope to come into crisp focus ? What do you see ? How large are the objects in  m ? Write your answers below: P1= Adjusted course focus, fine focus, centered image, placed 40X lens. I am able to see a line from part of the letter “e”. P4= Adjust iris diaphragm, centered image, adjusted course focus and fine focus. I can see the onion root tip. M1= I had to rotate the micrometer from top to bottom. 145 Micrometers P2= Adjusted iris diaphragm, adjusted course and fine focus and centered specimen. Looks like black dots in little boxes. P5= Adjust diaphragm, course and fine focus and center image. Pink background with little flakes of white. M2= I had to move the XY controls to get the image right next to the micrometer. 8.0 Micrometers P3= Centered image, adjusted course and fine P6= Adjusted Course Focus and fine focus, XY M3= I had to move the XY controls to get the image 1 Keiser University Online Microbiology I Virtual Lab 1 Worksheet Microscopy & Gram Staining focus. Shows blue shapes with dark blue specks in the middle. Controls to center image. I see bluish shapes with a dark blue dot in the center. right next to the micrometer. 2 Micrometers 4. Label the above components of the compound light microscope: A. Ocular Lens F. Rheostat B. Stage (XY) Controls G. Spring Loaded Stage Clip C. Course Focus H. Illuminator D. Fine Focus I. Iris Diaphragm E. Lenses 5. Define the following: a. magnification The seeming increase in size of an object viewed under the microscope b. resolution The power to show details clearly. The optic ability to 2 Keiser University Online Microbiology I Virtual Lab 1 Worksheet Microscopy & Gram Staining distinguish detail such as the separation of closely adjacent objects. c. contrast converts phase shifts in light passing through a transparent specimen to brightness changes in the image d. ocular micrometer A glass disk that fits in a microscope eyepiece and that has a ruled scale; when calibrated with a slide micrometer, direct measurements of a microscopic object can be made. 6. Complete the following table: Objective magnification Ocular magnification Total magnification 10X 10X 100X 45X 10X 450X 100X 10X 1000X 75X 10X 750X 45X 5X 225X 7. While looking through the 40X objective lens, you use the micrometer and measure an insect’s leg. It is 16 mm. What is the actual size of the insect leg? The actual size of the insect’s leg is 40 um. 16 ocular micrometer units x 2.5 Calibration factor = 40 um ocular micrometer 8. Explain why the light microscope is also called the compound microscope. It is composed of two lens systems. One lens system, called the objective, is placed close to the specimen and produces an enlarged and resolved image of the specimen. This image is in turn enlarged by another lens system, called the eyepiece or ocular, which is placed near to the eye of the observer. 9. Explain why the specimen must be centered in the field of view on low power before going to high power High power takes in a much smaller area, you may not be able to find the specimen if it is off to one side. The entire field of view may be in the blank area of the slide. 10. Describe how to make a proper wet mount of the letter “e”  Use the eyedropper to place a drop of water on the center of a microscope slide  Use the tweezers to position the letter "e" in the center of the drop. 3

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