Download Lab02MicroscopeAndCells

Principles of Biology
By
Frank H. Osborne, Ph. D.
Lab 2 - Microscope and Cells
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.
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.
Ocular Lens
The
Microscope
Objective
Lenses
Coarse
Adjustment
Stage
Fine
Adjustment
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.
Focusing the Microscope
6. Turn to the next higher power
7. Find the object.
8. Focus slowly.
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.
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
Onion Skin Cells
Nucleolus
Cell wall
Cytoplasm in Strands
Nucleus
Vacuole
B. Plant cells
b. Elodea cells
i. nucleus
ii. chloroplasts
iii. cytoplasm
iv. vacuole
v. cell wall
3. Some cells have cytoplasmic streaming
(cyclosis).
Elodea leaf
Elodea leaf magnified 100X
Elodea spicule (pointy cell) magnified 400X
Cell wall
Chloroplast
Cytoplasm
Vacuole
Nucleus
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.
Finally, you become an expert.
The End
Lab 2
Microscope and Cells