Fundamentals of Anatomy and Physiology

Cell Structure 59

LABORATORY

Cell Structure continued

EXERCISE:

replaced by new cells. Therefore, these cells

usually come off the cheek in masses.^

3. Under low power of the microscope, scan
   your slide until you find individual cells.

(^) Now turn to high power. Notice the cells
are flat and irregular in shape. Locate the
nucleus, the nucleolus, the nuclear mem-
(^) brane, the cytoplasm, and the cell mem-
(^) brane. The dark granules in the cytoplasm
are probably mitochondria. You may also
(^) see some vacuoles.
B. Plant Cells

1. Cut an onion into quarters; with forceps, strip
   a piece of thin epidermis from the inside of
   one of the leaves of the onion bulb. Make a
   wet mount by placing it in a drop of water; try
   to avoid folding of the epidermal tissue.


2. Compare this to the human epithelial cell.
   These plant cells have rigid cell walls, easily
   observable under low power. Switch to high
   power and observe the light nucleus with
   a number of nucleoli. Notice the large cell
   vacuole and clear cytoplasm. There are no
   chloroplasts in the onion bulb.


3. Take a young leaf from the top of an aquatic
   Elodea or Cabomba plant and make a wet
   mount of it to observe large green chloro-
   plasts in the cells of this plant. Notice the
   large number of chloroplasts in the cyto-
   plasm of the cells under low power. There
   are so many chloroplasts that any other

C.^ Living Single-Celled Animal:^

Paramecium

Make a wet mount of Paramecium by putting a

drop of the culture (supplied by your instructor)

onto a microscope slide covered with a glass cover

slip. Paramecium is a single-celled ciliate animal

(Figure 3-16). Examine your slide under low

power because the Paramecia are large and

actively swim in the watery medium. Observe the

animal’s structures, especially the beating cilia

seen around the edge of the cell membrane, the

large macronucleus, and the oral groove.

Cilia

Food vacuole^

Cytoplasm

Trichocysts

Macronucleus

Micronucleus

Oral groove

Gullet

cellular contents are obscured. In young

leaves, the cytoplasm streams; thus, the

chloroplasts will be moved in a current

within the cell. Again note the rigid cell wall

made of cellulose. The cell membrane is

pushed up against the cell wall, so it is not

Contractile

vacuole (^) Anal
pore
(^) ®
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visible as a separate entity.
Figure 3- 16 The structure of a
Paramecium.