You would expect to find higher myoglobin levels in oxidative muscle fibers than in glycolytic muscle fibers.

Question

Answer the following statement true (T) or false (F)

Answer 1

True

Clarify Question

• What is the key concept addressed by the question?
   o The question asks about myoglobin concentration in oxidative or glycolytic muscle fibers.

• What type of thinking is required?
   o You are being asked to apply your knowledge of myoglobin to predict if the concentration is higher in oxidative or glycolytic muscle fibers.

Gather Content

• What do you know about myoglobin? What other information is related to the question?
   o Fibers that contain numerous mitochondria and have a high capacity for oxidative phosphorylation are classified as oxidative fibers. Most of the ATP production by such fibers depends on blood flow to deliver oxygen and nutrients to the muscle. Not surprisingly, therefore, these fibers are surrounded by many small blood vessels and contain large amounts of myoglobin, an oxygen-binding protein that increases the availability of oxygen in the fiber by providing an intracellular reservoir of oxygen. The large amounts of myoglobin present in oxidative fibers give these fibers a dark-red color.
   o By contrast, glycolytic fibers have few mitochondria but possess both a high concentration of the proteins involved in glycolysis and large stores of glycogen, the storage form of glucose. Corresponding to their limited use of oxygen, these fibers are surrounded by relatively few blood vessels and contain little myoglobin. The lack of myoglobin is responsible for the pale color of glycolytic fibers and their designation as white muscle fibers.

Choose Answer

• Given what you now know, what information is most likely to produce the correct answer?
   o Oxidative muscle fibers need more oxygen to generate ATP so they will have more myoglobin to help bind and store this oxygen. Glycolytic muscle fibers are anaerobic and do not need as much oxygen and will have lower myoglobin concentrations.

Reflect on Process

• Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
   o This question asked you to apply your knowledge of myoglobin to predict if the concentration is higher in oxidative or glycolytic muscle fibers. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you realize that myoglobin binds oxygen in muscle cells? Did you think that glycolytic muscle fibers needed more oxygen than oxidative muscle fibers?