1. Effects of Temperature on Cell Respiration

Cell respiration can be viewed as a series of enzyme catalyzed reactions in which carbohydrates, proteins, and fats are broken down to carbon dioxide and water with the release of energy. During the process, hydrogen is removed from the fuel molecules and oxygen is consumed. With this background information, students measure oxygen consumption and hydrogen liberation in germinating barley at different temperatures. The program provides eight calibrated respirometers for measurement of oxygen consumption and the chemicals required to perform a graphic dye reduction assay. The exercise introduces students to a fundamental biological process and provides insight into seed structure and germination. This exercise is now available as an individual unit Click Here for more details.

2. Extraction and Analysis of an Enzyme from Wheat

Acid phosphatase is present in many plant tissues where it catalyzes the removal of phosphate groups from macromolecules at low pH. In this exercise, students prepare a cell-free extract from wheat germ and determine the amount of the enzyme present in the extract. The experiment offers practical experience with enzyme extraction procedures and is an excellent introduction to the analysis of enzyme activity and basic enzyme kinetics. A colorimeter is desirable but not absolutely necessary for this exercise. This exercise is now available as an individual unit. Click Here for more details.

3. Location of an Enzyme in Plant Cells and Tissues

Flowering plants are multicellular organisms and different enzymes are frequently produced in different tissues and in different cell types. This concept is illustrated in the first part of the exercise where students use an enzyme histochemical procedure to show that peroxidase is produced by cells that comprise a layer in the corn seed called the aleurone as shown in the figure below. In the second part of the exercise, a similar procedure is used by the student to show that peroxidase is found in the cell wall of onion epithelial cells.

        A                        B                   C                D

The picture shows typical results of the first portion of Experiment 3. Germinating corn seeds were incubated in water (A), iodine (B), tetrazolium (C), or in a peroxidase substrate (D). Note that the triangular embryo in C exhibits a high rate of respiration, the aleurone layer in D contains peroxidase and the starchy endosperm in B is stained with iodine.

4. Osmolarity and a Cytological Bioassay

In this exercise, osmosis is examined in living onion epithelial cells which are used in a cytological assay to determine the osmolarity of an unknown sucrose solution provided with the program.

The onion root has served as a model system for the study of mitosis, cell elongation, and cell differentiation in plants. In this experiment, students examine various segments of onion roots for cytological differences and then correlate their cytological findings with different respiration rates in the root segments. The exercise provides practical experience with tissue fixing, staining and slide making procedures, and introduces students to the concepts of cell division, the cell cycle, and differentiation in plant systems.

A first step in plant recombinant DNA research frequently involves the isolation of DNA from plant tissue. Students perform this procedure in the exercise where they prepare DNA from wheat germ by a simple procedure that uses a detergent, salt, and alcohol.

Price List - Basic Laboratory Program 4