Lab 3 Microscopes
BIOLOGY 181 Lab # 4 Microscopy and Cells Lab
A microscope is a tool that enables us to see objects and organisms that are invisible to the naked eye. Microscopes use a series of two or more lenses to magnify an illuminated image. Magnification is a measure of how big an object looks to your eye compared to “life size.” Microscopes also enhance the resolution of an image. Resolution is the ability to distinguish between two objects that are close together. Resolution can be increased using immersion oil. All microscopes have three basic components: 1) magnifying lenses; 2) a means of focusing; and, 3) a source of illumination (light). A compound microscope uses two lenses to view an object. The ocular (eyepiece) is at the top of the microscope …show more content…
and contains a lens with the ability to magnify objects 10 times (10x) life size. The objective lenses are small cylinders located on the revolving nosepiece. Each objective has a different magnification (10x, 40x, 100x). The total magnifying power of the lenses is calculated by multiplying the magnification of the ocular (10x) by the magnification of the objective (10-100x). Table 4.1 Parts and Functions of a Light Microscope Part
Main switch Light intensity knob Eyepiece Field of view Interpupillary distance adjustment Diopter adjustment ring Condenser Aperture iris diaphragm knob Stage Specimen holder Y-axis knob x-axis knob Revolving nosepiece Objectives: 4x,10x,40x,100x oil Coarse focus adjustment knob Fine focus adjustment knob Adjusts the light intensity Contains viewing lenses (10x) Circular illuminated area seen through the eyepieces Adjusts to match distance between student’s eyes Adjusts focuses for student’s individual eyesight Channels light through specimen and objective lens Opens/closes amount of light passing through the specimen Resting surface for the specimen slide Holds specimen slide in place on stage Front and back movement of the specimen holder Right and left movement of the specimen holder Rotates (black ridged band) and positions objective lenses Allows magnification of specimen Locates specimen and focuses under 10X objective lens Focuses specimen under 40x and 100x oil objective lenses
Function
Controls power (on/off) to the scope
4-1
Handling the Microscope 1.
Use two hands to transport the microscope. Place one hand under the base at the front of the microscope and the other hand under the handle on the rear of the arm (Figure 2.1).
Figure 4.1 Moving and Handling a Microscope 2. Once the microscope is on the lab bench, connect the power cord to the microscope and plug it into an outlet. 3. Using Figure 2.2 as a guide, locate and identify each ocular and objective lens. Record the magnification of each lens and the total magnification. Total magnification is calculated by multiplying the magnification of the ocular (10x) by the magnification of the objective (10x, 40x, 400x).
Lens Used
10x objective lens 40x objective lens 100x objective lens with oil
Lens Magnification
Total Magnification
4-2
Figure 4.2. Parts of a Microscope 4-3
Figure 4.3. Microscope …show more content…
Controls
4-4
Microscope Operation
1. Turn on microscope using the power switch located on the right hand side of the microscope frame. 2. Use the light intensity knob to adjust brightness. 3. Locate the nosepiece and rotate the 4x objective into place above the stage. 4. Place condenser in the highest position. 5. Open specimen holder arm, insert slide, and then carefully close arm. 6. Center the specimen directly over the light source using the Xaxis and Y-axis knobs. 7. Move stage to its highest position using the coarse focus adjustment knob. Slowly lower stage using the coarse adjustment knob until specimen appears in field of view. 8. Use the fine adjustment knob to bring specimen into sharp focus. Avoid using the coarse adjustment knob with higher magnification lenses as they can easily break the slide.
9. Adjust light intensity using the iris diaphragm knob located on the front of the condenser. Lower magnifications require low light, higher magnifications require high light.
10. Look into the ocular lens and adjust the eyepieces to match the distance between your pupils (interpupillary distance). You should see one clear, circular field of view. 11. Look through the right eyepiece with the right eye and bring the image into sharp focus using the fine adjustment knob. 12. Look through the left eyepiece with the left eye and turn the diopter adjustment ring to focus the specimen.
Oil Immersion 1. Bring slide into focus with the 40X lens. 2. Rotate nosepiece until 40X objective is out of position and nosepiece is about halfway to the 100X objective. 3. Add a large drop of immersion oil onto the slide. If 40x objective accidentally comes into contact with the oil, immediately clean the objective with lens paper and microscope cleaner. 4. Rotate the 100X objective into place. 5. Slowly turn the fine adjustment knob toward you until you see the specimen come into view. Never use the coarse adjustment knob with the 100x objective lens! 6. Open the iris diaphragm or use the light intensity knob (5) to adjust light source. Microscope Care and Storage 4-5
1. 2. 3. 4. 5.
Remove slide from microscope stage. Turn nosepiece to lowest magnification (4x). Center and lower stage away from objective lens. Use lens paper to remove all oil from lenses, slides, and stage. Replace plastic cover and place in cabinet with the eyepieces facing the back of the cabinet.
Wet Mounts Wet mounts are made when looking at organisms grown in a liquid culture or when observing dry specimens placed in water. You can prepare a wet mound of your own cheek cells using the illustrated technique (Fig. 4.4). First, obtain a piece of paper towel about two feet long and place it on the workbench in front of you. Use a flat toothpick to gently scrape cells from the lining of your mouth. Stir these into a drop of water on a slide, add a drop of methylene blue, and a coverslip. Observe under the microscope.
Figure 4.4. Making a Wet Mount NAME _________________ BIOLOGY 181 4-6
Microscopy and Cells Lab Worksheet OBJECTIVES: 1. 2. 3. 4. 5. Observe and describe the main features of prokaryotic and eukaryotic cells Observe and describe the main features of animal and plant cells Observe and describe the organization of plant and animal tissues Determine the total magnification at which your observations have been performed Correlate your microscopic samples to the timing of apparition of different unicellular and multicellular organisms
PROCEDURES: 1.
2. Make a wet mount of your cheek cells (see p. 4-6 for instructions). Examine your slide under the compound microscope and draw a few cheek cells at 400X in the space provided. Be prepared to discuss and present your drawings Make an Elodea leaf wet mount: obtain an Elodea leaf and make a wet mount — do not use methylene blue or other dye in this case. Examine the wet mount with your compound microscope at 400X. Focus on the fleshy layer inside the leaf (do not focus on the surface layer), on the cells filled with chloroplasts (the green bead-like structures). Draw a few of these cells in the space provided; label chloroplasts and cell walls. Do the cells form a tissue? Compare your observation with electron micrograph # 6. Be prepared to discuss and present your drawings Examine “Bacterial Types,” “Columnar Epithelia,” “Human Blood,” “Amoeba,” and “Paramecium.” Examine your slides under the compound microscope and draw cells and tissues in the space provided. Be prepared to discuss and present your drawings after comparing your observations with the following electron micrographs: “Bacterial Types” → “Human Blood” → “Columnar Epithelia” → 4. electron micrograph # 1 electron micrographs # 4 electron micrographs #
5
3.
Locate your cells on the biological evolution timescale chart
Please complete the following drawings and turn your assignment at the end of the lab. Label your drawings and indicate the magnification in each case. Each drawing is worth 5 4-7
points.
1. Bacterial Types X
2. Amoeba sp. or Paramecium sp. X
4-8
3. Your Cheek Cells X
4. Red and White Blood Cells X
4-9
5. Columnar Epithelia X
6. Elodea leaf X
4-10
4-11
A microscope is a tool that enables us to see objects and organisms that are invisible to the naked eye. Microscopes use a series of two or more lenses to magnify an illuminated image. Magnification is a measure of how big an object looks to your eye compared to “life size.” Microscopes also enhance the resolution of an image. Resolution is the ability to distinguish between two objects that are close together. Resolution can be increased using immersion oil. All microscopes have three basic components: 1) magnifying lenses; 2) a means of focusing; and, 3) a source of illumination (light). A compound microscope uses two lenses to view an object. The ocular (eyepiece) is at the top of the microscope …show more content…
and contains a lens with the ability to magnify objects 10 times (10x) life size. The objective lenses are small cylinders located on the revolving nosepiece. Each objective has a different magnification (10x, 40x, 100x). The total magnifying power of the lenses is calculated by multiplying the magnification of the ocular (10x) by the magnification of the objective (10-100x). Table 4.1 Parts and Functions of a Light Microscope Part
Main switch Light intensity knob Eyepiece Field of view Interpupillary distance adjustment Diopter adjustment ring Condenser Aperture iris diaphragm knob Stage Specimen holder Y-axis knob x-axis knob Revolving nosepiece Objectives: 4x,10x,40x,100x oil Coarse focus adjustment knob Fine focus adjustment knob Adjusts the light intensity Contains viewing lenses (10x) Circular illuminated area seen through the eyepieces Adjusts to match distance between student’s eyes Adjusts focuses for student’s individual eyesight Channels light through specimen and objective lens Opens/closes amount of light passing through the specimen Resting surface for the specimen slide Holds specimen slide in place on stage Front and back movement of the specimen holder Right and left movement of the specimen holder Rotates (black ridged band) and positions objective lenses Allows magnification of specimen Locates specimen and focuses under 10X objective lens Focuses specimen under 40x and 100x oil objective lenses
Function
Controls power (on/off) to the scope
4-1
Handling the Microscope 1.
Use two hands to transport the microscope. Place one hand under the base at the front of the microscope and the other hand under the handle on the rear of the arm (Figure 2.1).
Figure 4.1 Moving and Handling a Microscope 2. Once the microscope is on the lab bench, connect the power cord to the microscope and plug it into an outlet. 3. Using Figure 2.2 as a guide, locate and identify each ocular and objective lens. Record the magnification of each lens and the total magnification. Total magnification is calculated by multiplying the magnification of the ocular (10x) by the magnification of the objective (10x, 40x, 400x).
Lens Used
10x objective lens 40x objective lens 100x objective lens with oil
Lens Magnification
Total Magnification
4-2
Figure 4.2. Parts of a Microscope 4-3
Figure 4.3. Microscope …show more content…
Controls
4-4
Microscope Operation
1. Turn on microscope using the power switch located on the right hand side of the microscope frame. 2. Use the light intensity knob to adjust brightness. 3. Locate the nosepiece and rotate the 4x objective into place above the stage. 4. Place condenser in the highest position. 5. Open specimen holder arm, insert slide, and then carefully close arm. 6. Center the specimen directly over the light source using the Xaxis and Y-axis knobs. 7. Move stage to its highest position using the coarse focus adjustment knob. Slowly lower stage using the coarse adjustment knob until specimen appears in field of view. 8. Use the fine adjustment knob to bring specimen into sharp focus. Avoid using the coarse adjustment knob with higher magnification lenses as they can easily break the slide.
9. Adjust light intensity using the iris diaphragm knob located on the front of the condenser. Lower magnifications require low light, higher magnifications require high light.
10. Look into the ocular lens and adjust the eyepieces to match the distance between your pupils (interpupillary distance). You should see one clear, circular field of view. 11. Look through the right eyepiece with the right eye and bring the image into sharp focus using the fine adjustment knob. 12. Look through the left eyepiece with the left eye and turn the diopter adjustment ring to focus the specimen.
Oil Immersion 1. Bring slide into focus with the 40X lens. 2. Rotate nosepiece until 40X objective is out of position and nosepiece is about halfway to the 100X objective. 3. Add a large drop of immersion oil onto the slide. If 40x objective accidentally comes into contact with the oil, immediately clean the objective with lens paper and microscope cleaner. 4. Rotate the 100X objective into place. 5. Slowly turn the fine adjustment knob toward you until you see the specimen come into view. Never use the coarse adjustment knob with the 100x objective lens! 6. Open the iris diaphragm or use the light intensity knob (5) to adjust light source. Microscope Care and Storage 4-5
1. 2. 3. 4. 5.
Remove slide from microscope stage. Turn nosepiece to lowest magnification (4x). Center and lower stage away from objective lens. Use lens paper to remove all oil from lenses, slides, and stage. Replace plastic cover and place in cabinet with the eyepieces facing the back of the cabinet.
Wet Mounts Wet mounts are made when looking at organisms grown in a liquid culture or when observing dry specimens placed in water. You can prepare a wet mound of your own cheek cells using the illustrated technique (Fig. 4.4). First, obtain a piece of paper towel about two feet long and place it on the workbench in front of you. Use a flat toothpick to gently scrape cells from the lining of your mouth. Stir these into a drop of water on a slide, add a drop of methylene blue, and a coverslip. Observe under the microscope.
Figure 4.4. Making a Wet Mount NAME _________________ BIOLOGY 181 4-6
Microscopy and Cells Lab Worksheet OBJECTIVES: 1. 2. 3. 4. 5. Observe and describe the main features of prokaryotic and eukaryotic cells Observe and describe the main features of animal and plant cells Observe and describe the organization of plant and animal tissues Determine the total magnification at which your observations have been performed Correlate your microscopic samples to the timing of apparition of different unicellular and multicellular organisms
PROCEDURES: 1.
2. Make a wet mount of your cheek cells (see p. 4-6 for instructions). Examine your slide under the compound microscope and draw a few cheek cells at 400X in the space provided. Be prepared to discuss and present your drawings Make an Elodea leaf wet mount: obtain an Elodea leaf and make a wet mount — do not use methylene blue or other dye in this case. Examine the wet mount with your compound microscope at 400X. Focus on the fleshy layer inside the leaf (do not focus on the surface layer), on the cells filled with chloroplasts (the green bead-like structures). Draw a few of these cells in the space provided; label chloroplasts and cell walls. Do the cells form a tissue? Compare your observation with electron micrograph # 6. Be prepared to discuss and present your drawings Examine “Bacterial Types,” “Columnar Epithelia,” “Human Blood,” “Amoeba,” and “Paramecium.” Examine your slides under the compound microscope and draw cells and tissues in the space provided. Be prepared to discuss and present your drawings after comparing your observations with the following electron micrographs: “Bacterial Types” → “Human Blood” → “Columnar Epithelia” → 4. electron micrograph # 1 electron micrographs # 4 electron micrographs #
5
3.
Locate your cells on the biological evolution timescale chart
Please complete the following drawings and turn your assignment at the end of the lab. Label your drawings and indicate the magnification in each case. Each drawing is worth 5 4-7
points.
1. Bacterial Types X
2. Amoeba sp. or Paramecium sp. X
4-8
3. Your Cheek Cells X
4. Red and White Blood Cells X
4-9
5. Columnar Epithelia X
6. Elodea leaf X
4-10
4-11