Sperm cells contain many more mitochondria than most other types of cells. Why do you think sperm have such a large number of mitochondria?

The motile sperm or spermatozoon uses a flagellum to move towards the egg during reproduction. The beating of the flagellum causes the sperm to "swim" towards the egg; however this beating must have an energy source for it to occur. Just as you or I need food as an energy source to swim, the sperm needs an energy source to swim.

Since the journey between the testes and the egg is a long journey for a single cell measuring 25 µm (0.0025mm) in length, a lot of energy is required for it to complete the journey. The high abundance of glucose can be explained because glucose can be used by the sperm cell to provide energy in the form of adenosine triphosphate, or ATP.

The reason why there are so many mitochondria in a sperm cell is a bit of a mystery because sperm cells produce energy mainly by a process called glycolysis, which does not require mitochondria.