Mitochondria

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 in which they lived within larger cells  called as endosymbiosis.

In many organisms, the mitochondrial genome is inherited maternally. This is because the mother’s egg cell donates the majority of cytoplasm to the embryo and mitochondria inherited from the father’s sperm  are usually destroyed.

The mtDNA found in the egg is nonrecombinant, meaning that it does not combine with any other DNA and it is in cytoplasm so that it is passed down  the direct maternal .

Structure of Mitochondria:

Mitochondria are surrounded by a double-membrane system, consisting of inner and outer mitochondrial membranes separated by an intermembrane space. The inner membrane forms numerous folds  called cristae, which extend into the interior called  matrix . Each of these components plays distinct functional roles, with the matrix and inner membrane representing the major working compartments of mitochondria.This foldings increasing the available surface area.

The outer mitochondrial membrane is freely permeable to small molecules and contains special channels capable of transporting large molecules. In contrast, the inner membrane is far less permeable, allowing only very small molecules to cross into the matrix. The matrix contains the deoxyribonucleic acid (DNA) of the mitochondrial genome and the enzymes.
Inner mitochondrial membrane functions:

The inner mitochondrial membrane contains proteins with five types of functions:

1. Those that perform the redox reactions of oxidative phosphorylation
2. ATP synthase, which generates ATP in the matrix
3. Specific transport proteins that regulate metabolite passage into and out of the matrix
4. Protein import machinery

    5. Mitochondrial fusion and fission protein. 

 

 Mitochondria functions:

• The Krebs cycle
• The electron transport chain
• Chemiosmosis
• The energy balance of cellular respiration