Mitochondria are semi-autonomous organelles found in eukaryotic cells referred to as the "powerhouses" of the cell. They contain their own DNA separate from the cell's nucleus and likely evolved from bacteria in an endosymbiotic relationship. Mitochondria range from 0.5 to 1.0 micrometers in diameter and have an outer and inner membrane. Their primary function is producing energy through ATP synthesis in the inner membrane, but they are also involved in cellular signaling, differentiation, growth, and apoptosis.

1. Mitochondria structure
 By
 Dr. Harinatha Reddy Aswartha

2.  In 1890, mitochondria was first described by German
scientist Richard Altmann.
 The mitochondria referred to as the 'power houses' of the cell.
 Mitochondria is considered as semi autonomous cell organelle.

3. Organization and Function of Mitochondria:

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5.  The mitochondria ranges from 0.5 to 1.0 micrometer in diameter.
 The mitochondria also involved in other cellular activities like
signaling, cellular differentiation, cell growth and also play
important role in the aging process (Apoptosis).

6. The Genetic System of Mitochondria:
 Mitochondria contain their own genetic system, which is separate
and distinct from the nuclear genome of the cell.
 Mitochondria are thought to have evolved from bacteria that
developed a symbiotic relationship with larger cells
(endosymbiosis).

7.  Mitochondrial genomes are usually circular DNA molecules like
those of bacteria, which are present in multiple copies per
organelle.
 In humans and animals Mitochondrial genome about 16 kb in size.
 But substantially larger mitochondrial genomes found in yeasts
(approximately 80 kb) and plants (more than 200 kb ).


8. Outer membrane:
 It is smooth and is composed of equal amounts of phospholipids
and proteins.
 The outer membrane is freely permeable to nutrient molecules, ions,
energy molecules like the ATP and ADP molecules.

9. Inner membrane:
 The inner membrane of mitochondria is more complex in structure.
 It is folded into matrix many times and is known as the cristae.
 ATP Synthesis present in inner-membrance due to the presence of
ATP synthase
 ATP synthase made up of two subunits: F0 and F1 subunits.

11. Intermembrane space:
 It is the space between the outer and inner membrane of the mitochondria,
it has the same composition as that of the cell's cytoplasm.
 There is a difference in the protein content in the intermembrane space.
Matrix:
 The matrix of the mitochondria is a complex mixture of proteins and
enzymes. These enzymes are important for the synthesis of ATP
molecules, mitochondrial ribosomes, tRNAs and mitochondrial DNA

12. Function of Mitochondria:
 The most important function of the mitochondria is to produce
energy.
 The mitochondria also help in building certain parts of blood and
hormones like testosterone and estrogen.
 The mitochondria also play important role in the process of
apoptosis or programmed cell death.
 Abnormal death of cells due to the dysfunction of mitochondria
can affect the function of organ.