Mitochondria

Mitochondria are filamentous, granular, cytoplasmic structures which are the site of cellular respiration and generation of ATP. Hence, they are also called powerhouse of the cell. They are absent in prokaryotic cell and present in eukaryotic cells except mature or old RBC. They occur from one to many numbers in cells. They are found in large number in metabolically active cells. Eg; muscle cells, liver cells. Their shape is variable and is usually found in filamentous cylindrical oval or spherical rod-shaped, cup-shaped. Their average size is 2-6 micron. This is second largest in the animal cell and third largest in the plant cell.

Structure

The structure of mitochondria consists of two membranes and chamber.

Membrane

Mitochondria are bounded by two membranes outer and inner. The outer membrane is smooth and the inner membrane is folded inward into numerous finger-like projection called cristae which increase the surface area for cellular respiration. On the matrix side, the cristae behave many tennis rackets like particles known as oxysome/ F₁ particles/ elementary particles. Each of oxysome is differentiated into head, stalk, and base. The headpiece of oxysome contains an enzyme known as APT synthetase which helps in the synthesis of APT molecules.

ATP; a Deno sim phosphate (universal energy carrier)

Chambers

Mitochondria contain two chamber outer and inner. The outer chamber lies in between inner and outer membrane. But the inner chamber lies next to the inner membrane and contains the dense fluid called the matrix. The matrix contains inorganic and organic chemical compound, DNA, Ribosome and enzymes of Krep cycle.

Semi-autonomous nature of mitochondria

Due to the presence of DNA, ribosomes and the capacity of energy generation the mitochondria can synthesis some of the required protein but for other protein, they depend on upon the nucleus and the ribosomes of the cell. Hence, they are called semi-autonomous cell organelle.

Functions of Mitochondria

• Mitochondria are called powerhouse of the cell because they are the site of aerobic respiration and generation of ATP molecules.

C₆H₁₂O₆ +6O₂? 6CO₂ + 6H₂O + 38 ATP molecule

• Various intermediates formed during respiration are utilized to synthesis other chemical compounds like chlorophyll and cytochromes.
• They help in the synthesis of fatty acid and amino acid.
• They also regulate calcium ion concentration inside the cell.
• They are the site of thermogenesis(heat generation).