Using the Microscope Lab 1 Biology 101

Today in Lab Lab etiquette/safety - Sign and turn in the first page of the manual 3. Using the microscope 4. Find something neat – Use pond water, prepared slides, go outside and find something, your choice. 5. Don’t forget! QHMs for next week!

What did the invention of the microscope enable? DUH…. to look at tiny stuff Individual cells could be observed Allowed scientists to see that all cells are very similar, but often take on different functions Allowed us to see very small things Typical cell = 0.02 mm Our eyes can only see 0.2 mm Invented around 1675; telescopes around 1605. Fundamentally changed how we saw ourselves and nature. Dutch Inventor: Antoni van Leeuwennhoek

Determining Total Magnification Multiply the magnification of each set of lenses: Total magnification = magnification of objective X magnification of eyepiece Scanning power: eyepiece ______x times objective _____x = _____x Low power: High power: Oil immersion power: 10 4 40 Page 4, lab manual

Magnification vs. Resolving Power Def: ratio of image size to actual size; an apparent enlargement of an object. Resolving Power - resolution Def: a microscope’s ability to distinguish between two objects that are very close together as separate; what allows us to see detail.

Parts of the Compound Microscope

Using the Microscope ATTENTION! Important to follow these steps: Plug in and turn on the light source. Adjust light source as needed. Clean the objectives and eyepieces with lens paper Move the stage to its lowest position. Make sure the lowest objective is in place (4x). Place the slide on the stage and secure it with the slide clips/holder. Use the stage controls to center the slide over the light source. Look at the slide from the side of the microscope, not through the eyepieces. Looking through the eyepieces, use the coarse adjustment knob to bring the slide toward the objective. Soon you will see the image come into view. After you get the image as clear as possible with the coarse adjustment, use the fine adjustment knob to further focus the image. You may now go to a higher objective if you want, but be sure to ONLY use the fine adjustment knob to focus. (Also, be sure you are going to the next highest objective and NOT the oil immersion). The microscope objectives should be parfocal, as an image is focused with one objective, it will also be in focus in the other objectives.

We will be using a ruler to measure the field of view. What is the field of view in this image? 7 mm

Micrometer The images we will be looking at under the microscope are often too small to be measured in millimeters. Thus, we use the micrometer… 1 mm = 1000 µm 1 µm = 0.001 mm

Preparing a Wet Mount

Oil Immersion PLEASE be very careful!! Procedure: After focusing in the high power objective, move the nosepiece half way between this and the oil immersion objective. Place a small drop of oil on the coverslip. Move the oil immersion objective into and through the oil and secure in position. ONLY use the fine adjustment (and only a little bit) to focus

Oil Immersion cont. After you are finished, be sure to wipe the oil immersion lens with LENS paper and LENS CLEANER to remove the oil. ONLY use lens paper or else you will damage the objectives. Seriously. Use lens paper, not Kimwipes.

REMINDERS: Work productively and efficiently Think creatively, critically, and freely. ASK QUESTIONS! Return materials in the same condition you found them Take thorough notes, draw pictures, answer all questions in your lab notebook, and come up with a QHM on microorganisms or something you saw today. Before you leave make sure your work station is in the same condition as you found it. Don’t forget! Question + Hypothesis + Methods! = QHM Also: be sure you have provided an email, know how to access the website, and have spoken with me personally if you are concerned about your writing ability and the research paper.