AFAA Personal Trainer Certification Practice Exam

What is the role of mitochondria in muscle cells?

1. To produce proteins

2. To store calcium

3. To generate energy through oxidation

4. To synthesize glycogen

The correct answer is: To generate energy through oxidation

Mitochondria play a crucial role in muscle cells as the powerhouse responsible for generating energy. They achieve this through a process known as oxidative phosphorylation, which uses oxygen to convert nutrients into adenosine triphosphate (ATP), the energy currency of the cell. This energy is essential for muscle contraction and overall cellular function, making mitochondria vital for sustained physical activity and performance, particularly in endurance-type exercises. While muscle cells do involve protein synthesis, calcium storage, and glycogen synthesis, these functions are carried out by different cellular structures or processes. For instance, ribosomes are primarily responsible for protein production, the sarcoplasmic reticulum is involved in calcium storage, and glycogen is stored in the cytoplasm within specialized granules. Therefore, the mitochondria's primary and most significant role is in energy generation, which directly supports muscle function and endurance.