The mitochondrial matrix contains a circular
double stranded DNA (mtDNA), RNA and
ribosomes. Thus, the mitochondria are equipped
with an independent protein synthesizing
machinery. It is estimated that about 10% of the
mitochondrial oroteins are produced in the
mitochondria.
The mitochondria are composed of a double
membrane system. The outer membrane is
smooth and completely envelops the organelle.
The inner membrane is folded to form cristae
(Latin - crests) which occupy a larger surface
area. The internal chamber of mitochondria is
referred to as matrix or mitosol.

Mitochondrial DNA is Circular and Double-stranded
Mitochondrial DNA (mtDNA) is a unique type of DNA found in the mitochondria, which are small organelles within the cells that are responsible for energy production. Here are the key characteristics of mitochondrial DNA:
1. Circular structure:
- Unlike the linear DNA found in the nucleus, mtDNA has a circular structure.
- This circular shape allows for efficient replication and maintenance of the DNA within the mitochondria.
2. Double-stranded:
- Mitochondrial DNA consists of two strands, known as the heavy strand and the light strand.
- The two strands are complementary, meaning they can form base pairs with each other.
- This double-stranded nature is important for the stability and functioning of mtDNA.
3. Naked:
- Mitochondrial DNA is considered "naked" because it does not associate with proteins called histones.
- Unlike nuclear DNA, which is tightly wound around histones to form chromatin, mtDNA is not organized into nucleosomes.
4. Maternal inheritance:
- One interesting aspect of mtDNA is that it is primarily inherited from the mother.
- This is because the mitochondria in the sperm cells are usually destroyed after fertilization, while the mitochondria in the egg cells are passed on to the offspring.
- As a result, the mtDNA in an individual is derived from their mother's lineage.
In summary, mitochondrial DNA is circular and double-stranded, and it is considered "naked" since it is not associated with histones. Its unique characteristics play a crucial role in the functioning and inheritance of mitochondrial DNA.