USA Biology Olympiad (USABO) Practice Exam

What is a primary role of myoglobin in muscle cells?

1. Transports oxygen in blood

2. Facilitates energy production

3. Stores oxygen

4. Regulates metabolic processes

The correct answer is: Stores oxygen

Myoglobin plays a crucial role in muscle cells primarily as an oxygen storage molecule. It is a globular protein that binds to oxygen more effectively than hemoglobin, the protein responsible for oxygen transport in the blood. In muscle tissue, myoglobin serves to store oxygen and release it when the muscle requires it during periods of high activity, such as intense exercise. This is particularly important because muscle cells need a readily available supply of oxygen for aerobic respiration, which generates ATP to power muscle contractions. By having myoglobin localized within muscle cells, there is increased efficiency in the use of oxygen during physical exertion, allowing for sustained energy production when blood oxygen levels may not be sufficient to meet immediate demands. While transporting oxygen in the blood, facilitating energy production, and regulating metabolic processes are vital functions in the body, these roles are not primarily associated with myoglobin itself. Instead, they are functions attributed to other proteins and systems within the body, with myoglobin specifically focusing on oxygen storage within muscle tissues.