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STUDENT OBJECTIVE

Students observe prokaryotic and eukaryotic cells using living material and prepared slides. Students will observe basic plant and animal tissue types and use simple staining methods.

EQUIPMENT	AMOUNT
	(Class of 24 with 8 groups)
Compound microscopes with oil immersion objectives, if possible	1/student
Microtome	Demonstration
MATERIALS
Immersion oil, if oil immersion objectives used	8 dropper bottles
Slides	1 box/lab
Coverslips, #1 small square (18 mm x 18 mm)	1/2 oz/lab
Razor blades, single-edge	12/lab
Approved Sharps Disposal container	1/lab
Test tubes, 5 ml	4/lab
Pasteur pipettes	6/lab
Spatula	4/lab
Dropper bottle with distilled water	6/lab
Flower petals, leaves, algae, insects, worms, etc.	as appropriate
Cotton fiber	2 cotton balls/lab
Wax blocks with embedded specimens (leaves, stems, etc.)	Demonstration (of microtome)
Toothpicks	box/lab
Cultures Blue-green algae: Anabaena, Anacystis (Microcystis) (CBS#15-1710, #15-1715, #15-1840) Plain yogurt (grocery) Protozoa: Mixed protozoa amoebas, ciliates, flagellates (CBS#13-1934)*	1 culture each/lab   8 oz/lab   1 culture each/lab
Live plants
Onion	1/lab
Prepared slides Human skin (CBS#31-4522)* Frog skin (CBS#31-4486)* Skeletal muscle (CBS#31-3256)* Areolar connective tissue (CBS#31-2686) Cow neurons (CBS#31-3570) Pine stem, tangential section or macerate (CBS#30-1322)* Pumpkin stem, longitudinal section or macerate (CBS#30-3062)* Gram-stained slide of mixed cocci, bacilli, spirilla (CBS#29-3958)*	1/student but sharing is possible

Demonstration slides
Slides of tissues for unknown identification	3/lab

* Please refer to the Appendix for name and address of supplier

SOLUTIONS

Methyl cellulose or protoslo (CBS#87-5183)
Neutral red stain (Improves contrast but can kill organisms) (CBS#87-6830)
1% methylene blue stain (optional) (CBS#87-5911)
India ink

PREPARATION

One Week before Lab

1. Supplies should be checked and replaced where needed. Purchase onions and yogurt and collect fresh and dry materials. Protozoa and blue-green algae cultures should arrive the day before lab. Keep algae in continuous, strong, but cool light.
2. Dye preparation:

Day of Lab

1. Make a mixed culture by adding equal portions of the blue-green algae cultures to a large test tube. Set the tube in a rack with an empty tube next to it. For dispensing the culture, a Pasteur pipette should be placed in the empty tube with instructions to use only a small drop when making a slide. Culture can be counterstained by adding 1 drop India ink to test tube.
2. Mix yogurt and water in a 1:3 proportion. Place in test tube. Use Pasteur pipette to dispense.

NOTES

Slides can easily be cleaned by students. Place a pan of strong detergent (Alconox, etc.) on the bench next to the sink.

CLASSROOM SUGGESTIONS

1. The time spent on this exercise can be decreased by viewing fewer specimens or increased by requiring drawings of all specimens.
2. A microtome can be set up for demonstration. Students can turn handle to get sections of approximately 10 micrometers. With an artist’s paintbrush, students can then try removing sections of wax block, either singly or in a strip of four or five slices. If a flat bowl or pan of water is provided, they can transfer the slice(s) to the surface of the water and see how thin the slice(s) is. Usually embedded specimens can be obtained from plant or animal anatomists on the staff. Warn students about sharp blade.
3. Supply houses and audiovisual companies have good slides (35 mm) and films on structure of cells, types of bacterial cells, and comparison of plant and animal tissue. These audiovisuals can be used at the end of the laboratory to summarize the exercise. Similar materials are now available on the www.
4. A minimum homework assignment would be to hand in tables identifying structures in an electron micrograph.
5. Students can share prepared microscope slides, reducing the cost of offering this exercise.
6. Check out the links for this lab topic at http://auth.mhhe.com/biosci/genbio/dolphin/

ANSWERS TO CRITICAL THINKING QUESTIONS

1. The prokaryotic cells and the eukaryotic organelles were similar in size. They are both membrane bound. The green color of the cyanobacteria and the green color of the chloroplast organelle is due to the presence of chlorophyll pigments.
   
   
2. Bone—matrix composed of mineral salts, primarily calcium carbonate and calcium phosphate, and collagen fibers.

   Cartilage—matrix composed of a dense network of collagenous fibers and elastic fibers embedded in a jelly-like substance (chondroitin sulphate).

   Loose connective tissue — matrix consists of collagenous, elastic and reticular fibers embedded in a semi-liquid intercellular substance.

   Blood — is considered a connective tissue as it consists of three cell lines suspended in a liquid matrix called plasma.

   Muscle — is not considered a connective tissue as an extracellular matrix is not a feature of this tissue. Its "connective" function is only as pertains to its attachment and insertion on bones.

3. Epidermal cell—flattened cells make highly connected covering.

   Tracheids—long and strawlike, perfect for water conduction.

   Muscle—long, thin, and often multinucleated with internal contractile filament arrays.

   Neuron—compact cell body with long extensions, perfect for making connections with other cells.

4. When the depth of field was restricted to the top of the chair, you would see only the back. When at the middle of the chair, you would see the end of the back, the start of the legs, and the seat. When at the bottom of the chair, you would see only the legs ending in the feet.

SUPPLEMENTAL MATERIALS