Mitochondria
Mitochondria are double membrane-bound organelles found in
eukaryotic cells that are involved in releasing energy from food. This process
is known as cellular respiration. It is a vital and major organelle of a
eukaryotic cell and is called the powerhouse of the cell.
Mitochondrion is a tube-like “organelles” Mito – “thread”,
Chondria – “granules”.
Mitochondria is the site of the citric acid cycle
(TCA cycle or Krebs cycle), which produces ATP that the cell uses for energy, take place in the matrix.
A cell may contain hundreds to as many as a thousand
mitochondria but red blood cells lack mitochondria.
Know here about the nucleus and the structure and function of nucleus.
Mitochondria Structure
A mitochondrion consists of two membranes-
1. Outer Mitochondrial Membrane
It is smooth, mostly made up of
phospholipid, cholesterol, and containing protein. It is free permeable to small
molecule and transports large molecules through channels of proteins “porins”.
2. Inner Mitochondrial Membrane
It consists series of inward folds organized into lamellae
(layers) called “cristae”. The inner membrane is highly folded, cristae
greatly increase the total surface area of the inner membrane. It is
selectively permeable.
The space within the inner mitochondria membrane is known
as the mitochondrial matrix.
Chemical energy produced by the mitochondria is stored in a
small molecule, called ATP (adenosine tri-phosphate).
The inner membrane contains a mitochondrial matrix in which
presents mitochondrial DNA (mtDNA ), enzyme ATP synthase (production of
ATP), specialized protein (transport protein) and ribosome.
3. Intermembrane Space
The space between the outer membrane and the inner
membrane is called intermembrane space. The main function of the intermembrane space of mitochondria
is oxidative phosphorylation.
Also, check out here the structure of
cytoskeleton.
Function of Mitochondria
The key function of mitochondria include-
1. The inner
mitochondrial membrane contains a variety of enzymes. It contains the enzyme ATP
synthase which generates ATP in the matrix.
2. It produces
energy in the form of ATP (adenosine tri-phophate) for various functions in the
cell and body. It converts nutrient into ATP through a reaction of “aerobic
cellular respiration” (presence of oxygen).
The main job of mitochondria is to perform “cellular
respiration” (the biochemical process of a cell) means it takes in nutrients from
the cell, breaks them down, and turns them into energy.
3. It generates
almost 90% of the chemical energy needed to power the cell's biochemical
reactions.
4. It is the site
for various types of biological reactions such as the Kreb cycle, lipid
biosynthesis, Beta-oxidation, etc, taking
place in the matrix.
5. It is the site
where NADH and FADH2 are promptly oxidized to produce ATP.
6. Each
mitochondrian has its own DNA molecule, and mitochondia can self
replicate( DNA to DNA). They can divide to increase in number, the replication
process is controlled by their own DNA.
Self-replication usually occurs in response to increase the cellular need for ATP, at the time of cell division.
7. Mitochondria
contain their own DNA and ribosomes. Mitochondrial ribosomes, called
mitoribosomes, perform protein synthesis inside mitochondria.
8. It stores and regulates
the calcium level in the body.
9. Mitochondria play essential roles in activating apoptosis (cell
death).
10. Age-related
degenerative disorders such as Parkinson’ disease, Alzheimer's disease, it may
occur due to damage of mitochondrial component.
Also, check out here function
of golgi apparatus and function
of endoplasmic reticulum.
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