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This collection of experiments was prepared for the novice to help bridge the gap between traditional animal physiology and the biochemistry of cell processes in animals. Following the step-by-step procedures in their laboratory manuals, students will study a variety of topics including the action, properties, and cell location of enzymes, and the evolution of mammalian proteins. 1. and 2. Quantifying Amylase Activity This exercise begins with a discussion of the digestive enzymes produced by the salivary glands, stomach, intestine and pancreas. The digestive system of a rodent is provided to familiarize students with anatomical features of the digestive organs of a mammal. Students are then given the opportunity to prepare enzyme extracts from pancreatic tissue and to determine the amount of amylase in the extracts and in their own saliva using the procedure described in the figure below. This exercise offers practical experience with enzyme extraction procedures and introduces the concept of the calibration curve for determining the levels of a specific enzyme in a complex mixture.
In the figure at the left, starch was incorporated into an agar gel, and samples containing amylase were placed in sample wells made in the agar. After one day, the starch was stained with iodine. Areas where the starch was degraded by amylase are seen as clear rings around the wells and the diameters of the rings are proportional to the concentration of amylase.
3. Proteases and Factors that Influence Enzyme Activity Students contrast the effects of pH on the activities of gastric pepsin and pancreatic chymotrypsin and relate their results to the acidic pH of the stomach and neutral pH of the small intestine. The effects of temperature and thermal denaturation on enzyme activity are also investigated. 4. Serum Enzymes and Disease Tissue injury often results in the leakage of large amounts of cellular enzymes into the circulatory system and measurements of the amounts and types of enzymes in serum are frequently made for the diagnosis of human disease. For example, inflammation of the pancreas is accompanied by the release of pancreatic amylase and proteases into the blood stream. In this exercise, students determine the levels of amylase and proteases in serum and compare these levels to those found in saliva and pancreatic extracts. 5. Evolution of Serum Proteins Each protein carries in its amino acid sequence information pertaining to its evolutionary history and origin, and provides clues to the evolutionary history of the organism in which it is found. Indeed, proteins existing today are in effect living fossils. This concept is illustrated in this exercise where students examine the ability of antibodies against cow serum proteins to react with serum proteins from cow, sheep, goat, horse, donkey, and chicken. The results of this study show that sheep and goat are most closely related to cow which is in agreement with classical taxonomy. This exercise is now available as an individual unit. Click Here for more details.
6. Identifying a Specific Enzyme in Chicken Erythrocytes by Enzyme Cytochemistry The concept that different enzymes are found in different regions of a cell is illustrated in this exercise. Here, students use the technique of enzyme cytochemistry to show that the enzyme lactate dehydrogenase is located in the cytoplasm of chicken erythrocytes. The exercise introduces students to the basic structure of animal cells and provides an illustration of an important technique used in modern cell biology. Eight chicken blood smears are provided for the experiment and microscopes are required. Contents of the Chemical Package (Click Here) Price List - Basic Laboratory Program 2
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