- Mitochondria, in a singular form known as mitochondrion, are cellular organelles that are not easily visible under the microscope unless they are specifically stained.
- The number of mitochondria per cell can vary, depending on the physiological activity of the cell.
- Mitochondria also exhibit a range of shapes and sizes.
- Typical Shape and Size:
- Typically, mitochondria are sausage-shaped or cylindrical, with a diameter ranging from 0.2 to 1.0µm (with an average of 0.5µm) and a length varying from 1.0 to 4.1µm.
- Double Membrane Structure:
- Each mitochondrion is a double membrane-bound structure with an outer membrane and an inner membrane, creating two distinct aqueous compartments, namely the outer compartment and the inner compartment.
- The inner compartment is filled with a dense homogeneous substance called the matrix. The outer membrane forms the continuous boundary of the organelle. The inner membrane contains numerous infoldings known as cristae, which increase the surface area for various processes.
- Both the outer and inner membranes possess specific enzymes associated with mitochondrial functions.
- Aerobic Respiration:
- Mitochondria are the primary sites of aerobic respiration, where cellular energy in the form of ATP (adenosine triphosphate) is produced. Hence, mitochondria are often referred to as the "powerhouses" of the cell.
- Genetic Material:
- The matrix of mitochondria contains a single circular DNA molecule, a few RNA molecules, 70S ribosomes, and components necessary for protein synthesis.
- Mitochondria are capable of dividing through a process called fission, which is essential for maintaining their population within the cell.