Mitochondria

Nature and occurrence:

• Several oval or cylindrical shape structures are found in cytoplasm
• Membrane bound organelle.
• It is known as powerhouse of the cell.

Structure:

• It is surrounded by double membrane.
• Outer membrane is smooth and porous.
• Inner membrane is rough forming many fingers like projections inside and these folds are known as cristae.
• Lumen inside is filled with the jelly like substance known as matrix.
• This matrix contains water and other biochemicals like carbohydrates, proteins, amino acids, lipids etc.
• Mitochondria contain its own DNA and ribosome.
• The membrane contains the transporters and enzymes that participate in electron transport chain and helps in synthesis of energy rich molecule.

Site of cellular respiration:

• Mitochondria are the site of cellular respiration. During respiration glycolysis occurs in cytoplasm and Kreb’s cycle, electron transport chain, oxidative phosphorylation takes place in mitochondria.

Oxidation of food:

• They help in the complete oxidation of food material.
• Glucose is completely oxidized to carbon dioxide and water in mitochondria.

Synthesis and storage of energy rich molecules:

• They contain the enzymes that help in synthesis of energy rich molecule called ATP-adenosine triphosphate.
• It also stores these energy rich molecule and supplies to the site where it is required further.

Synthesis of self regulatory protein:

• They contain their own DNA and ribosomes thus they are able to synthesize some of their own proteins which helps in controlling cellular respiration. Hence are called as semi autonomous organelle.

Synthesis of other components:

• Mitochondria also help in formation of blood components like heme, steroid hormones like testosterone and estrogen.
• They also help in maintenance of calcium level in different compartments of the cell.