Microscope Introductory Lab Series

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Arlene Morrison
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1 Microscope Introductory Lab Series Goals: SMBAT properly use the light microscope SWBAT explain the purpose and effect of the diaphragm on viewing a specimen SWBAT create a wet mount slide SWBAT identify the need to add stain to a specimen and properly do so Part A- Observing Threads: A Study of Depth of Field Materials: light microscope, prepared slide of crossed threads Instructions: 1. Set up a microscope and put the low power objective lens in place. 2. Obtain a prepared slide of crossed threads. 3. Place the slide on the stage and move the stage slips over the slide to hold the slide in place. 4. Turn on the light source. 5. Position the diaphragm so that the largest opening is used. This will allow the maximum amount of light to be used.. 6. Use the microscope coarse adjustment knob to locate the threads under low power. Center the slide so you are looking at the point where the threads cross. Use the fine adjustment knob to get the threads in the most focused view. 7. Draw a circle about 2 inches in diameter in your notebook, Make a drawing of the threads under low power in this circle. Use color and detail. 8. Label your drawing: "Thread Crosshairs" below the circle and write the correct magnification. Eyepiece lens magnification, 10x multiplied by the low power objective lens magnification, 4x; 10x multiplied by 4x equals 40x. Label this next to your drawing. 9. Change the objective lens to medium power (10x) to observe the threads. Make sure to have the threads centered in the middle of the field of view. 10. Use the microscope coarse adjustment knob to locate the threads under medium power. Center the slide so you are looking at the point where the threads cross. Use the fine adjustment knob to get the threads in the most focused view. The lens system of your microscope allows you to see clearly only one depth at a time under high power. In order to see objects at different depths, do the following: 11. Change the objective lens to high power (40x) and observe the threads at the point where they cross. Make sure to ONLY use the fine adjustment knob to get threads into focus. Turn the fine adjustment wheel back and forth by a quarter turn while looking through the microscope. This movement will give a three-dimensional view of the object. Try this technique while looking at the crossed threads. 12. Draw a circle about 2 inches in diameter in your notebook, Make a drawing of the threads under high power in this circle. Use color and detail.

2 13. Label your drawing: "Thread Crosshairs" below the circle and write the correct magnification. Eyepiece lens magnification, 10x multiplied by the high power objective lens magnification, 40x; 10x multiplied by 40x equals 400x. Label this next to your drawing. Answer the following questions in your notebook under the drawings of the slides.. 1. Describe the clarity and focus of the threads when you observed them under low power (4x). Where the threads clearly seen all the time, some of the time, none of the time? Explain why!! 2. Describe the clarity and focus of the threads when you observed them under high power (40x). Where the threads clearly seen all the time, some of the time, none of the time? Explain why!!

3 Microscope Introductory Lab Series Part B- Observing the letter "e": Image Orientation and Effects of Light Materials" light microscope, prepared slide of the letter "e" Instructions: 1. Set up a microscope and put the low power objective lens in place. 2. Obtain a prepared slide of the letter "e". 3. Place the slide on the stage with the "e" in a normal reading position for you; move the stage slips over the slide to hold the slide in place. 4. Turn on the light source. 5. Position the diaphragm so that the largest opening is used. This will allow the maximum amount of light to be used. 6. Look at the microscope from the side and use the coarse adjustment knob to get the stage as close to the low-power objective as possible. 7. Look through the eyepiece, keeping both eyes open. (It may seem difficult to keep both eyes open, but learning to do so helps to prevent eyestrain or headaches.) Slowly adjust the focus of the microscope using the coarse adjustment knob until the letters become clear. Then, use the fine adjustment to sharpen the focus. Move the slide left or right, forward or backward, until the letter "e" is in the center of the field of view. Do not turn the slide or pivot it. fhint: It should look a bit different) 8. In your notebook, draw a circle with a diameter of about 2 inches. Draw the letter "e" in the same size and position as you see it in the microscope.. 9. Label your drawing: "Letter e" below the circle and write the correct magnification. Eyepiece lens magnification, 10x multiplied by the jow power objective lens magnification, 4x; 10x multiplied by 4x equals 40x. Label this next to your drawing. 10. Carefully move the slide to the left while you look at the letter "e" under low power. Write and complete the following statements in your notebook. a. When we moved the slide to the left, the letter "e" move to the. b. When we moved the slide to the right, the letter "e" moved to the. c. When we moved the slide away from the microscope arm, the letter "e" moved to. d. In general, when a slide is moved, an observed under a microscope, it appears to move in the direction. 11. Look through the microscope; with the low power objective still in place; as you change the adjustment of the diaphragm. Write and complete the following statement in your notebook. a. The diaphragm controls Important Note: Before switching to high power, you should always position the specimen in the center of the field of view and use the fine adjust to sharpen the focus of the image. Never use the coarse adjustment when using high power. Doing so could break the slide or the microscope! 12. Center the letter "e" in the field of view under low power. Make sure you can see the letter "e" clearly. Adjust the coarse adjustment knob before the fine adjustment knob.

4 13. Rotate the objective lenses so that the high power objective lens (40x) is in place. Make sure that the lens does not hit the slide, but expect it to be very close Focus the letter "e" under the high power objective lens. DO NOT use the COARSE adjustment knob, ONLY the FINE adjustment knob. 15. In your notebook, draw a circle with a diameter of about 2 inches. Draw the letter "e" in the same size and position as you see it in the microscope. 16. Label your drawing: "Letter e" below the circle and write the correct magnification. Eyepiece lens magnification, 10x multiplied by the high power objective lens magnification, 40x; 10x multiplied by 40x equals 400x. Label this next to your drawing. 17. Answer the following questions with complete sentences in your notebook under the drawing of the letter "e" in high power: a. Describe the appearance of the image that you see. Are you seeing more or less of the letter "e" than you did at low-power? b. Is the field of view (the area that you are observing) larger or smaller when you use high power? 18. Look through the microscope (on high power) with the diaphragm at its largest setting. While looking through the eyepiece, switch the microscope to the jow power objective lens. Answer the following questions with complete sentences in your notebook under the drawing of the letter "e" in high to low power: a. When the low power objective lens is in place the light is (brighter/dimmer) than when the hioh power objective lens is in place. *

5 Microscope Introductory Lab Series Part C- Observing Plant and Animal Cells Materials: light microscope, two glass slides, stain, two coverslips, paper towel, water, an onion, and a toothpick Instructions: Onion cells 1. Peel a translucent piece of tissue from the onion. (The smaller the piece the better.) Translucent means that you can see light through the specimen, but it is not transparent. 2. Place the piece of onion on a glass slide and add a drop or two of the iodine solution. Cover the slide with a coverslip using your best wet-mount making techniques. As demonstrated by the teacher. 3. Observe the onion cell under both low and high power. 4. In your notebook, draw a circle with a diameter of about 2 inches. Draw one onion cell as you see it in the microscope under high power. Use color and detail. 5. Label your drawing: "Onion Cell" beiow the circle and write the correct magnification. Eyepiece lens magnification, 10x multiplied by the high power objective lens magnification, 40x; 10x multiplied by 40x equals 400x. Label this next to your drawing. 6. Label the nucleus, cytoplasm cell wall and cell membrane in your drawing. Cheek Cells ' 1. Place one drop of dye on clean slide. t 2. Wet wide end of toothpick with water. 3. Gently scrape inside of cheek with wide end of toothpick. 4. Place toothpick into the dye on slide and gently swirl to mix cheek cells with dye. 5. DO NOT REUSE TOOTHPICK. Throw the toothpick out. 6. Gently place coverslip on top of slide. As demonstrated by teacher. 7. Observe cheek cells under microscope using the low power objective lens (4x). 8. In your notebook, draw a circle with a diameter of about 2 inches. Draw one cheek cell as you see it in the microscope under jow power. Use cojor and detail. 9. Label your drawing: "Cheek Cell" below the circle and write the correct magnification. Eyepiece lens magnification, 10x multiplied by the low power objective lens magnification, 4x; 10x multiplied by 4x equals 40x. Label this next to your drawing. 10. Label the nucleus, cytoplasm and the cell membrane in your drawing. 11. Observe cheek cells under microscope using the medium power objective lens (1 Ox). 12. In your notebook, draw a circle with a diameter of about 2 inches. Draw one cheek cell as you see it in the microscope under medium power. Use color and detail. 13. Label your drawing: "Cheek Cell" below the circle and write the correct magnification. Eyepiece lens magnification, 10x multiplied by the medium power objective lens magnification, 10x; 10x multiplied by 10x equals 10Ox. Label this next to your drawing. 14. Label the nucleus, cytoplasm, cell membrane and any other organelle you think you see in your drawing. 15. Observe cheek cells under microscope using the high power objective lens (40x).

6 16. In your notebook, draw a circle with a diameter of about 2 inches. Draw one cheek cell as you see it in the microscope under high power. Use color and detail. 17. Label your drawing: "Cheek Cell" below the circle and write the correct magnification. Eyepiece lens magnification, 10x multiplied by the high power objective lens magnification, 40x; 10x multiplied by 40x equals 400x. Label this next to your drawing., 18. Label the nucleus, cytoplasm, cell membrane and any other organelle you think you see in your drawing. 19. Answer the following questions in your notebook under the drawings of the cheek ceils. Write your answers in complete sentences. a. Describe what cheek cells look like using low power lens. b. Describe what cheek cells look like using medium power lens. c. Describe what cheek cells look like using high power lens. ' 20. Answer the following conclusion questions in your notebook after your answers to #19 a,b,c. a. What is purpose of adding methylene blue dye to cheek cells? b. Which organelle is most prominent when looking at cheek cells under microscope? c. How many individual cheek cells can you see under low power? Medium power? High power?

Title: Using a Compound Light Microscope and Comparing Cells - Bacteria, Plant Cells and Animal Cells

Title: Using a Compound Light Microscope and Comparing Cells - Bacteria, Plant Cells and Animal Cells Background: Many objects are too small to be seen by the eye alone. They can be seen, however, with