Mitochondria: Structure, Function, and labelled Diagram with Detail explanation

Mitochondria: Structure, Function, and  labelled Diagram with Detail explanation


Mitochondria are membrane-bound organelles found in the cells of eukaryotic organisms. They are often referred to as the "powerhouses of the cell" because they play a central role in producing energy in the form of adenosine triphosphate (ATP) through cellular respiration. Mitochondria are believed to have originated from an ancient endosymbiotic event where a free-living prokaryotic organism was engulfed by a eukaryotic cell, eventually leading to a symbiotic relationship.


Mitochondria have a unique double-membrane structure. The outer mitochondrial membrane surrounds the entire organelle and separates it from the cytoplasm of the cell. The inner mitochondrial membrane is folded extensively, forming structures called cristae that protrude into the interior of the mitochondrion, known as the matrix. These inner membrane folds increase the surface area available for energy-producing chemical reactions.

The space between the outer and inner membranes is called the intermembrane space. Within the inner membrane, there is an electron transport chain (ETC), consisting of protein complexes that facilitate the transfer of electrons during cellular respiration.

Mitochondria also contain their own small amount of genetic material known as mitochondrial DNA (mtDNA). This genetic material is separate from the cell's nuclear DNA and encodes some of the proteins essential for mitochondrial function.


The primary function of mitochondria is to generate ATP, the energy currency of the cell. This energy production occurs through a complex series of chemical reactions called cellular respiration. The process of cellular respiration takes place within the mitochondria and involves the breakdown of glucose and other nutrients in the presence of oxygen.

The main steps of cellular respiration that occur within the mitochondria are:

a. Glycolysis (in the cytoplasm): 

Glucose is broken down into two molecules of pyruvate, generating a small amount of ATP.

b. Pyruvate Decarboxylation (in the mitochondrial matrix): 

Each pyruvate molecule is converted into Acetyl-CoA, producing carbon dioxide and high-energy electrons.

c. Citric Acid Cycle (Krebs cycle) (in the mitochondrial matrix): 

Acetyl-CoA enters the citric acid cycle, a series of chemical reactions that generate high-energy electrons and ATP precursors.

d. Electron Transport Chain (in the inner mitochondrial membrane):

 High-energy electrons generated during previous steps are passed through protein complexes of the ETC, creating a proton gradient.

e. Oxidative Phosphorylation (in the inner mitochondrial membrane):

 The flow of protons back into the matrix through ATP synthase leads to the synthesis of ATP.

Besides energy production, mitochondria are involved in other important cellular processes, such as calcium signaling, regulation of apoptosis (programmed cell death), and the synthesis of certain metabolites.

In summary, mitochondria are essential organelles that generate energy for the cell through cellular respiration, and they also participate in various other critical cellular functions. Their unique structure and function make them a fundamental component of eukaryotic cells and are essential for the survival and proper functioning of complex organisms.

Post a Comment