Mitochondria: Definition and Meaning and Mitochondria Diagram

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Definition and Meaning of Mitochondrion

  • It is a membrane bound organelle found in maist eukaryotic cells.

  • The term ‘mitochondrion’ is derived from the Greek words “mitos” and “chondrion” which means “thread” and “granules-like” respectively.

  • A German pathologist named Richard Altmann in the year 1890 was the first to describe it.

  • Eukaryotic cells are the cells that make up plants, animals, fungi, and many other forms of life.

  • Mitochondria are commonly between 0.75 and 3 μm in diameter and vary in size and structure.

  • It is popularly known as the Powerhouse of the cell.

  • These are found inside the cytoplasm and functions as the cell’s digestive system.

  • Thus, Mitochondria can be defined membrane-bound organelles present in the cytoplasm of all eukaryotic cells that produces adenosine triphosphate (ATP), the main energy molecule used by the cell.”

  • Mitochondria play a vital role in breaking down nutrients and generating energy-rich molecules for the cell.

  • Within the mitochondria, many of the biochemical reactions involved in cellular respiration take place.

Definition and Meaning of Mitochondrion

Definition and Meaning of Mitochondrion

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Functions of Mitochondria

  • To produce energy through the process of oxidative phosphorylation.

  • It also promotes the growth of new cells and cell multiplication.

  • It regulates the metabolic activity of the cell.

  • It also plays a vital role building certain parts of the blood and various hormones like testosterone and Oestrogen.

  • It further helps in maintaining an adequate concentration of calcium ions.

  • Some of the cellular activities in which it is involved are cellular differentiation, cell signaling, cell senescence, controlling the cell cycle and in cell growth.

  • It also helps in detoxifying ammonia in the liver cells.

Structure of Mitochondria

  • In both plant and animal cell, mitochondria are found as a double-membraned, rod-shaped structure.

  • The size of the mitochondria ranges from 0.5 to 1.0 micrometer in diameter.

  • The structure consists of:

    • Outer membrane

    • An inner membrane

    • A gel-like material called the matrix

  • The outer membrane and the inner membrane are made of proteins and phospholipid layers.

  • The surface of the mitochondrion is covered by the outer membrane. The large number of special proteins are known as porins.

  • As far as ions, nutrient molecules, energy molecules like the ADP and ATP molecules are concerned mitochondria is freely permeable.

Cristae

  • A crista is a fold in the inner membrane of a mitochondrion.

  • This helps in increasing the surface area inside the organelle.

  • The inner membrane is permeable only to oxygen and to ATP molecules.

  • Within the inner membrane of mitochondria, a few chemical reactions take place.

A mitochondrion, with labeled cristae.

A Mitochondrion, with Labeled Cristae

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Mitochondrial Matrix

  • In the mitochondrion, the matrix is the space within the inner membrane.

  • This matrix contains a viscous fluid that contains a mixture of enzymes and proteins.

  • Ribosomes, inorganic ions, mitochondrial DNA, nucleotide cofactors, and organic molecules are also present.

  • The enzymes present in the matrix play an important role in the synthesis of ATP molecules.

Mitochondrial Diseases

Mitochondrial diseases

Mitochondrial Diseases

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FAQs

Q 1. What are cristae?

Answer: The inner membrane of mitochondria with many folds forming a layered structure is known as cristae.

Q 2. What are the three Mitochondrial diseases?

Answer:

Three mitochondrial diseases are:

i) Alpers Disease

ii) Barth Syndrome

iii) Kearns-Sayre syndrome (KSS)

Q 3. List out some of the important functions of Mitochondria.

Answer:

Some of the important functions of Mitochondria are:

i) To produce energy through the process of oxidative phosphorylation.

ii) It also promotes the growth of new cells and cell multiplication.

iii) It regulates the metabolic activity of the cell.

iv) It also plays a vital role building certain parts of the blood and various hormones like testosterone and Oestrogen.

Q 4. What’s the structure of mitochondria?

Answer:

  • Mitochondria is a rod-shaped, double membraned organelle.

  • It can be found both in plant and animal cells.