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Cellular Respiration Experiments
Jenn Dearolf
2001 - 2002 Fellow

Cellular respiration is a fundamental concept in biology, and many classes do laboratory exercises where students study respiration in whole organisms. This approach, although useful, cannot be used to study the different stages of cellular respiration in isolation, and it may cause students to forget that respiration is a process that occurs in the cells of the organism.

The laboratory exercises presented here address these two issues using muscle tissue. Skeletal muscle is a useful tissue to study cellular respiration because its cells (fibers) have become specialized for different stages of the process. Some fibers use only glycolysis to produce the ATP needed for contraction, while other fibers utilize all of cellular respiration to fuel their activities. Thus, skeletal muscle provides a system where students can investigate the different stages of cellular respiration at the cellular level.

The first laboratory allows students to stain for the activity of an enzyme involved in the electron transport chain, nicatinamide adenine dinucleotide dehydrogenase (NADH-D). A digital image of one of the stained cross-sections of muscle is below. The fibers that are dark contain the enzyme and, thus, use all of cellular respiration to produce ATP.

Muscle stained for NADH-D

To study the fibers that utilize only glycolysis, students can investigate the acid buffering capacity of various muscle samples, like beef, pork, chicken, and fish. This investigation is based on the principle that muscle fibers that only use glycolysis to produce ATP also produce a large amount of lactic acid as a byproduct.

Thus, these cells must have some way to buffer the production of acid so that they can continue to function when lactic acid is being produced. A graph of student data is below, and it demonstrates that, out of the group of muscles investigated, the type with the greatest buffering capacity is from chicken.

Downloadable Files:

Teacher's Guide

Student Manual
(Please note that some figures have been omitted from this web version because of copyright protection.)



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