Mitochondria Diagram: Matrix, Ribosome & Cristae

Mitochondria are the powerhouses of the cell as they produce and control energy for the cell. Mitochondria diagram can help us in understanding its structure in a comprehensive manner.

• They are double membraned organelles with the outer membrane being smooth and inner membrane being folded.
• Mitochondria organelles are mostly found in eukaryotic cells.
• They produce energy in the form of ATP (adenosine triphosphate) through cellular respiration.
• Mitochondria independly reproduce through fission.
• Mitochondria also help in regulating the metabolism of the cell and controling calcium signaling.

Key Terms: Prokaryotes, Unicellular organisms, mitochondria diagram, nucleus, eukaryotes, cellular respiration, ATP

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What are Mitochondria?

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Mitochondria are cell organelles that are involved in metabolic cell activities such as cellular respiration, cell senescence, cell growth, etc. Mitochondria are double membraned organelles that are shaped like rods and are present in both animal as well as plant cells.

• Mostly found in eukaryotes, these organelles are found within the cytoplasm of the cell in the living cells.
• The diagram of Mitochondria is one of the highest scoring topic for the examinations.
• They are the powerhouse of the cell as mitochondria supply the cell the necessary energy by oxidising the available substrates.
• The energy is produced in the form of ATP in mitochondra through enzymatic oxidation of chemical compounds.

Functions of Mitochondria

Mitochondria have several important cellular functions which are as follows:

• Mitochondria produce ATP (adenosine triphosphate) through cellular respiration. Glucose and other molecules are broken down in this process to produce energy in the form of ATP.
• It also helps in regulating the cell metabolism, including the metabolism of lipids and amino acids.
• Mitochondria regulate calcium signaling within the cell. It is important for muscle contraction and cell death.
• Mitochondria can release pro-apoptotic factors in respose to certain signals, triggering cell death.

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Mitochondria Diagram

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Mitochondria have a unique structure within the cell that can be demonstrated through a well-labelled diagram of mitochondria.

1. The outer membrane of the organelle is smooth while the inner membrane is folded into cristae.
2. The space between the two membranes of mitochondria is known as the intermembrane space.
3. The space surrounded by the inner membrane is known as the mitochondrial matrix.
4. Mitochondria’s unique structure allows them to carry out important cellular functions such as producing energy.
5. The above mitochondria diagram shows the double membrane, cristae, intermembrane space, mitochondrial matrix, and location of enzymes and electron transport chains involved in cellular respiration.

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Structure of Mitochondria

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The shape and number of mitochondria and cristae in them, can significantly vary from one cell type to another. Tissues with high rate of oxidative metabolism such as muscle tissue have mitochondria with a high number of cristae. Both membranes of mitochondria have a high concentration of proteins.

Parts Of Mitochondria

Matrix

• Matrix is a gel like viscous fluid with a mixture of ribosomes, enzymes, mitochondrial DNA, inorganic ions, organic molecules and nucleotide cofactors. 
• It plays an important role in cellular respiration and producing ATP which is the energy currency of the cell.
• Ribosomes and circular DNAs are also present inside the matrix of the mitochondria.
• The presence of Riboflavin makes the matrix pale yellow in color.

Ribosomes

• Ribosomes present in the mitochondria are known as the mitoribosome or mitochondrial ribosome.
• The function of ribosomes in the mitochondria is the synthesis of proteins and energy conversion
• Mitochondrial ribosomes are different from the ones in the cytoplasm of the cell, as they have a slightly different structure.
• The presence of their own ribosomes allows mitochondria to produce proteins that are necessary for their function.
• It is a protein complex which functions by translating mitochondrial mRNAs encoded in mtDNA.

Cristae

• The inner membrane of the mitochondria surrounded by the folds of mitochondrial matrix, as shown in the mitochondria diagram, is known as the cristae.
• They help in increasing the surface area of the inner membrane which in turn increases the Adenosine Triphosphate (ATP) synthesis.
• The knob-like structures present on the cristae are called the oxysomes or elementary particles. These structures assist in the synthesis of ATP.

Inner membrane

• The inner mitochondrial membrane is a folded membrane containing proteins involved in oxidative phosphorylation.
• It is the process of ATP production from the energy released via electron transport chain.
• The inner membrane is impermeable to most ions and small molecules, thus is known as special membrane transporters. 
• These transporters are necessary to maintain electrochemical gradient across the membrane, important for the ATP generation.

Outer Membrane

• The outer membrane of mitochondria is the smooth membrane that surrounds the organelle.
• It is made up of a phospholipid bilayer containing proteins called porins allowing small molecules to diffuse in and out of the mitochondria.
• The outer membrane also plays a role in the fusion and fission of mitochondria.
• It also holds a number of enzymes with a wide variety of functions.

Inter membrane Space

• Mitochondia is made up of 2 compartments – the inter membrane space and the mitochondrial matrix.
• The region between the inner and outer membrane of mitochondria is called the intermembrane space.
• The intermembrane space is further divided into two sub-compartments, the lumen, and the intra cristae space.
• This space is primarily responsible for the modification of proteins, transportation of molecules, and the regulation of respiratory chain complexes.

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Things to Remember

• Mitochondria are organelles found in most eukaryotic cells that produce energy in the form of ATP through cellular respiration.
• The outer membrane of mitochondria is smooth and the inner membrane is folded into structures called cristae. 
• The cristae provide a large surface area for enzymes and electron transport chains involved in cellular respiration, in the mitochondrial matrix.
• Dysfunction of mitochondria has been linked to metabolic disorders, neurodegenerative diseases, and cancer.
• A mitochondria diagram shows its double membrane, cristae, intermembrane space, and mitochondrial matrix.
• Mitochondria is responsible for the synthesis of ATP and is therefore called the powerhouse of a cell.