Exercise 1: Focusing, Positioning and calculating the size of cells Under the ‘Try This’ tab, complete the puzzles (P1- P6) presented to bring the items into focus. Use the check lists to make sure you have completed all steps Under the ‘Try This’ tab, complete the measurement puzzles (M1-M3) and write the answers here:
M1 = __150___ micrometers at __10x__Objective Power (scale is 1 unit = __10_micrometers)
M2 = __8.0____ micrometers at _100x_____Objective Power (scale is 1 unit = _1.0__micrometers)
M3 = ___2.0__ micrometers at __100x____Objective Power (scale is 1 unit = _1.0__micrometers)
Exercise 2: Viewing a typed letter ‘e’ with your scope.
Obtain the slide with an ‘e’ on it from the slide selections. Place the ‘e’ slide right side up on the stage with the letter ‘e’ over the hole in the stage. Using the techniques described in the ‘getting started tour’, focus on the letter on the lowest objective power. What do you notice about the orientation of the letter as you look through the microscope? In other words, how does the ‘e’ position compare to how it looks on the slide when looking at the microscope? Upside down At the lowest power, what is the total magnification of the image? 16x Adjust the position of the slide so that a portion of the letter is in the center of the viewing field. Now, rotate the next higher objective in place. If the image is not clear, use only the fine tuning knob to adjust. At 10x, what is the total magnification of the image now? 40x At 40x, what is the total magnification of the image now?160x At 100x, what is the total magnification of the image now?400x
Exercise 3: Human cheek cells.
Your cheeks are lined with very thin cells that can easily be removed for viewing under a microscope. These cells are called epithelial cells and they line the outside and inside of your body. Cells are small, but large enough to be viewed with a light microscope. The following procedure shows how you would obtain these cells. However, since this is a virtual lab, the cheek cells have already been collected and stained. They are stained with methylene blue to view some sub-cellular parts. This is the actual procedure, but please proceed to placing the cheek smear slide on your ‘virtual’ microscope and bringing into focus. 1. Gently scrape the inside of your cheek with a toothpick.
2. Using a circular pattern, spread some saliva in the middle of a slide.
3. Place a small drop of stain on the saliva smear. The less stain you use, the better the results will be!
4. Place a cover slip on the stained smear.
Knowing the objective scale in Exercise 2, estimate and record the diameter of a single cheek cell in micrometers.
Diameter = ___4__________ micrometers
What power of objective lens did you use? 100
What was the total magnification?400