Lab Safety No eating or drinking!!! Long hair must be tied back Clean up your workstation before you leave! Return all materials to the storage sites Clean glassware and wipe down countertops Follow directions for disposing used slides, solutions, or other biohazard waste. Wash your hands
The Care and Use of the Microscope Lab Exercise #4
Objectives Identify and know the functions of the parts of the compound microscopes Learn to use the microscope Determine magnification power Prepare a simple stained slide and view it under the microscope (wet mount) Recognize the difference between a compound and a stereomicroscope
Cells The human eye is unable to distinguish objects that are smaller than 0.1 mm. The microscope is an essential tool used to view cells and tissues. You must treat the microscope with CARE! Some of the cells and tissues we use in the labs are stained with dyes so that the cells and some of their parts are visible.
Antony van Leeuwenhoek 1632-1723 He is commonly known as "the Father of Microbiology Built a single-lens microscope by grinding lenses. Saw the first microorganisms (bacteria, yeast, and protists)
To increase magnification, the lens diameter was decreased, but it made it difficult to see through because they were so small. A two lens system was created in which the second lens magnified the image of the first lens. Led to the construction of the compound microscope (2 lens system)
Compound Microscope Compound microscopes have higher resolution and magnification 40-1000X
Lab Safety-The Microscope Carry the microscope with 2 hands in the upright position 1 at the base and 1 holding the arm/neck Clean oculars and objectives with lens paper before and after use Do not drag/slide the microscope, fully lift it to move it When you are done, change the magnification to the lowest power, and body tube turned down near the stage. When you are done, I must inspect your microscope before you put it up and leave.
Resolution versus Magnification Resolution is the ability to distinguish between two points The ability to see details Magnification refers to the enlargement of the image of the object being examined Typically, the better the magnification, the better the resolution.
Magnification Magnification is simply the number of times an image's size is enlarged. In practice this simply means that if we view a 1 mm line at 2x it appears to us as a 2 mm line.
Resolution Resolution is a measurement of how well the smallest details of an image can be discerned. The wavelength of the light source used in a microscope limits the resolution, and thus the magnification that can be achieved. The white light limits magnification to 1000X, but other microscopes like the UV and electron microscopes can achieve high resolution and magnification Does A or B have better resolution? A B
FIVR Class 2012 SEM image of a retina Electron Microscopes Electron Cryomicroscopy (TEM) Structure of TRPV1 Used to investigate subcellular structures. Use an electron beam instead of light and provide high resolution and magnification (1,000,000X). There are 2 types: transmission electron microscope (TEM) and the scanning electron micrscope (SEM). TEM uses ultra thin tissue sections stained with heavy metal ions, and the electron beam passes through the specimen and the image is projected onto a fluorescent screen. In SEM, the electron beam bounces off the surface of the specimen to reveal detail.
Dissecting versus Compound Dissecting miscroscope is used to view opaque specimens 10-20X Compound microscopes have higher resolution and magnification 40-1000X
Components of the compound microscope Oculars (eye pieces)-pair of lenses used to look into the microscope and magnify the image 10X The distance between the oculars should be adjusted to match the distance between your eyes so that the 2 images overlap and you only see 1 image. Body tube-allows the light to pass from the objective to the oculars and holds the ocular and revolving nose piece. Revolving nosepiece-holds the 4 objective lenses each of which can be moved into position above the opening in the stage. Feel it click into place. Objective- lenses attached to the revolving nose piece. Scanning 4X (find the specimen) Low power 10X (initially focus the slide) High-dry 40X (to see greater detail) To calculate total magnification, the power of the objective lens is multiplied by the power of the ocular.
Components of the compound microscope Stage- platform on which the slide is placed Use the metal clips to hold the slide in place 2 knobs that move the slide up/down or back/forth (image moves in opposite direction because the image is inverted) Course and Fine adjustment knobs- move either the stage or body tube. The image can be focused by increases or decreasing the distance between the objective and the slide. Use course for initial focusing and fine for precise focusing Condenser lens-located under the stage used to focus the light from below. Can affect the intensity and clarity of the image. Position can be adjusted by pinion knob. Iris diaphragm lever- increases or decreases the amount of light hitting the object Light Source lamp that provides light for illumination Base- flat bottom part of the microscope arm-provides support. ALWAYS use two hands when carrying the microscope. One hand to support the base One hand to hold the arm
Focusing the compound microscope 1. Clean lenses with lens paper only! Do not use other types of tissue or paper. 2. Turn on illuminator and adjust light to high 3. Click lower power lens into position over the stage 4. Fit your slides inside the calipers 5. Use stage knobs to move the slide into the middle of the stage --make sure the specimen is in the center of the stage so that light passes through it. 6. Adjust oculars to correct distance 7. Start at the lowest magnification (scanning) and with the stage furthest away (using the course adjustment knob) 8. Turn course adjustment until image comes into view and becomes sharp 9. Use the fine adjustment for complete focusing 10. Adjust the light if needed 11. If a specific part needs to be further magnified, bring it to the center of the field of view using the stage knobs. At higher magnifications the field of view is smaller. 12. Use the revolving nosepiece to switch to the low power objective 13. The low power objective will come close to the slide! Do not use the course adjustment or you will snap your slide in half! 14. Use only fine adjustments so the image comes into focus. 15. Repeat steps 11-14 using the high power objective.
Lab Report 47-48 Answer the questions by examining the compound microscope 49-50 YOUR FIRST OBSERVATION Follow stops 1-11 Slide and wax pencil Answer questions on page 53 50-51 FIELD OF VISION Follow steps 1-6 Micrometer Answer questions on page 54 51 DEPTH OF FOCUS Follow steps 1-4 Slide with thread Answer questions 54-55
Returning the microscope I must approve your microscope condition before it is placed in the cabinet. Before you unplug the microscope, turn off the light source switch. Clean all the lenses with lens paper Change the magnification to the lowest power, and body tube turned down near the stage Loosely wrap the electric cord around the base of the microscope Use 2 hands when transporting the microscope Complete all lab report questions before leaving