1. Principles of Biology By Frank H. Osborne, Ph. D. Lab 2 - Microscope and Cells

2. A. The microscope is used to magnify objects. B. The object on the slide is magnified by the objective lens. 1. The shortest scanning lens (4X) is used to search for objects on the slide. 2. The low power (10X) lens is used for general magnification. 3. The high power (40X) objective lens is used for close-up work. Do not use the high power lens to observe thick preparations.

3. C. The image produced by the objective lens is magnified by the ocular lens (10X). 1. The scanning lens gives a total magnification of 40X. 2. The low power lens gives a total magnification of 100X. 3. The high power lens gives a total magnification of 400 X.

4. The Microscope Ocular Lens Objective Lenses Coarse Adjustment Fine Adjustment Stage

5. Focusing the Microscope 1. Use the lowest power. 2. Look at the slide, not through the ocular lens. 3. Bring the lens and slide as close together as possible. 4. Now, look through the ocular lens and focus upward slowly until you see something. 5. Put the object in the exact center of the field of view.

6. Focusing the Microscope 6. Turn to the next higher power 7. Find the object. 8. Focus slowly.

7. Cells A.Animal cells 1.Animal cells do not have a cell wall. 2.With our microscope, you can see the nucleus and the cytoplasm. 3.Methylene blue dye is used to see the nucleus and cytoplasm better.

8. Cells B. Plant cells 1. Plant cells have a cell wall. 2. You can see more parts. a. Onion skin cells i. nucleus ii. nucleolus iii. cytoplasm in strands iv. vacuole v. cell wall

9. Onion Skin Cells Nucleolus Cell wall Cytoplasm in Strands Nucleus Vacuole

10. B. Plant cells b. Elodea cells i. nucleus ii. chloroplasts iii. cytoplasm iv. vacuole v. cell wall 3. Some cells have cytoplasmic streaming (cyclosis).

11. Elodea leaf Elodea leaf magnified 100X

12. Elodea spicule (pointy cell) magnified 400X Cell wall Chloroplast Nucleus Cytoplasm Vacuole

13. Drawings A. Draw one cell or several cells. B. Label each of the parts you saw. Do not label parts that cannot be seen, like the cell membrane. C. Do not include air bubbles. D. Label the magnification that you used.

14. Finally, you become an expert.

15. The End Lab 2 Microscope and Cells