Mitochondria are one of the important cell organelles present inside a cell. Every cell has at-least one or more numbers depending on the requirement. The cells of those organs with high physiological activity posses more number of mitochondria and in those organelles with low physiological activity have less number of mitochondria. Further inside a particular cell, their location varies and generally are more concentrated in the regions of the cell with high physiological activity.
Structure of mitochondria:
They are sac like double membranes structures present in the cytoplasm of cell. They can be seen under an electron microscope. Their shape differs from being either spherical, club, oval or even thread like structures.
They are divided into two compartments i.e. an inner compartment and an outer compartment. The inner compartment lies within the inner membrane. The outer compartment is in between outer membrane and inner membrane.
The inner compartment is also called as matrix and is surrounded by inner mitochondrial membrane. This membrane is divided into several folds within which lies the matrix. The membrane also has permeability and hence the substances can move from matrix to fluid in the outer compartment and vice-versa.
The foldings on the inner membrane are termed as cristae which have elementary particles and some enzymes.
The enzymes on cristae and those in matrix are involved in production of energy through breakdown of carbohydrates and also protein formation required by mitochondria. Even the single stranded DNA lies in the matrix.
The outer compartment is surrounded by outer mitochondrial membrane towards exterior and also by inner mitochondrial membrane towards interiors of mitochondria.
This outer mitochondrial membrane is smooth without any folding or projections. It is selectively permeable to substances from and into the mitochondria and cytoplasm. Thus it can act as reserve for various substances needed for mitochondrial energy generation and excretion of related waste bi-products.
1. It is well known fact that mitochondria are responsible for cell energy supply.
2. They produce energy in the form of ATP (adenosine triphosphate) by breakdown of carbohydrate substrates in presence of oxygen.
3. They are the organelles which house the TCA cycle (tri-carboxyllic acid cycle) and other respiratory cycles of the cell.
4. They also produce bi-products like glutarate, glyco-oxalic acid formed TCA cycle which can further form glutamine, glycine like amino acids required for normal physiology and metabolism of the cell.
5. They promote cell growth and also signal transmission. In especially nerve cells they are concentrated at nerve ending to promote nerve growth and also supply energy for nerve conduction.
6. Mitochondria also are partly responsible for cell death in case of trauma. The membrane of mitochondria releases apoptosis factors leading to programmed cell death.