Introduction
Mitochondria are often called the “powerhouses of the cell” because they produce most of
the energy required for various cellular activities. This energy is released in the form of ATP
(adenosine triphosphate) through the process of cellular respiration.
Mitochondria are fascinating because they are semi-autonomous organelles, meaning they
have their own DNA, RNA, and ribosomes and can produce some of their own proteins.
They are present in almost all eukaryotic cells, whether plant or animal, but are absent in
prokaryotes like bacteria.
The number of mitochondria in a cell depends on its energy requirement. For example,
muscle cells and liver cells contain hundreds to thousands of mitochondria, while less active
cells may have only a few.
Structure of Mitochondria
1. Shape, Size, and Number
Shape: Mitochondria are usually spherical or rod-shaped, but they can also appear thread-
like or oval depending on the cell type.
Size: Typically, they measure about 0.5 to 1.0 µm in diameter and 1.0 to 10 µm in length.