Page 1
Electron Mitochondria
Institute of Lifelong Learning, University of Delhi
Lesson: Electron Mitochondria
Lesson Developer: Renu Kathpalia
College/Department: Kirori Mal College, University of Delhi
Page 2
Electron Mitochondria
Institute of Lifelong Learning, University of Delhi
Lesson: Electron Mitochondria
Lesson Developer: Renu Kathpalia
College/Department: Kirori Mal College, University of Delhi
Mitochondria
Institute of Lifelong Learning, University of Delhi 1
Table of Contents
Chapter: Mitochondria
? Introduction
? Historical Background
? Size and number
? Morphology
o The outer membrane
o The innermembrane
o The inter membrane space
o Matrix
? Mitochondrial DNA
? Mitochondrial Biogenesis
? Marker Enzymes
? Functions of mitochondria
? Cellular respiration
? Glycolysis
? Kerb’s cycle
? Oxidative phosphorylation
? Electron transport chain
? Chemiosmotic coupling
? Role in apoptosis
? Cell specific functions
? Endosymbiotic origin of mitochondria
? Import of proteins into mitochondria
? Summary
? Exercise/ Practice
? Glossary
? References/ Bibliography/ Further Reading
Page 3
Electron Mitochondria
Institute of Lifelong Learning, University of Delhi
Lesson: Electron Mitochondria
Lesson Developer: Renu Kathpalia
College/Department: Kirori Mal College, University of Delhi
Mitochondria
Institute of Lifelong Learning, University of Delhi 1
Table of Contents
Chapter: Mitochondria
? Introduction
? Historical Background
? Size and number
? Morphology
o The outer membrane
o The innermembrane
o The inter membrane space
o Matrix
? Mitochondrial DNA
? Mitochondrial Biogenesis
? Marker Enzymes
? Functions of mitochondria
? Cellular respiration
? Glycolysis
? Kerb’s cycle
? Oxidative phosphorylation
? Electron transport chain
? Chemiosmotic coupling
? Role in apoptosis
? Cell specific functions
? Endosymbiotic origin of mitochondria
? Import of proteins into mitochondria
? Summary
? Exercise/ Practice
? Glossary
? References/ Bibliography/ Further Reading
Mitochondria
Institute of Lifelong Learning, University of Delhi 2
Introduction
In eukaryotic cells most of the generation of metabolic energy occurs in the organelle called
mitochondria (singular: mitochondrion) often referred to as the power house of the cell.
The energy is derived by the breakdown of carbohydrates, amino acids and fatty acids and
is used in the formation of energy rich molecules the ATP (often referred to as the energy
currency of the cell) by the process of oxidative phosphorylation.
Mitochondria are found in the cytoplasm of nearly all eukaryotic cells and occupy a
substantial portion of the cytoplasm. They are large enough to be resolved in the light
microscope but are generally not visible as they lack contrast. Special stains are used to
make them visible, for e.g. Janus Green B.
Each cell contains hundreds to thousands of mitochondria (e.g., the liver cell contains 1000-
2000 mitochondria occupying one fifth of the cell volume). Mitochonria are double
membrane organelles. Their number and size varies in metabolically different cells. The
mitochondria are highly plastic and constantly change their shape and position. In some
cells, however, they remain in a fixed position and provide ATP, e.g., the muscle cells and
around the flagellum of a sperm.
Figure: The Electron micrograph of normal adult muscle showing mitochondria (arrows).
Source:http://missinglink.ucsf.edu/lm/ids_104_musclenerve_path/student_musclen
erve/normal2.html
Page 4
Electron Mitochondria
Institute of Lifelong Learning, University of Delhi
Lesson: Electron Mitochondria
Lesson Developer: Renu Kathpalia
College/Department: Kirori Mal College, University of Delhi
Mitochondria
Institute of Lifelong Learning, University of Delhi 1
Table of Contents
Chapter: Mitochondria
? Introduction
? Historical Background
? Size and number
? Morphology
o The outer membrane
o The innermembrane
o The inter membrane space
o Matrix
? Mitochondrial DNA
? Mitochondrial Biogenesis
? Marker Enzymes
? Functions of mitochondria
? Cellular respiration
? Glycolysis
? Kerb’s cycle
? Oxidative phosphorylation
? Electron transport chain
? Chemiosmotic coupling
? Role in apoptosis
? Cell specific functions
? Endosymbiotic origin of mitochondria
? Import of proteins into mitochondria
? Summary
? Exercise/ Practice
? Glossary
? References/ Bibliography/ Further Reading
Mitochondria
Institute of Lifelong Learning, University of Delhi 2
Introduction
In eukaryotic cells most of the generation of metabolic energy occurs in the organelle called
mitochondria (singular: mitochondrion) often referred to as the power house of the cell.
The energy is derived by the breakdown of carbohydrates, amino acids and fatty acids and
is used in the formation of energy rich molecules the ATP (often referred to as the energy
currency of the cell) by the process of oxidative phosphorylation.
Mitochondria are found in the cytoplasm of nearly all eukaryotic cells and occupy a
substantial portion of the cytoplasm. They are large enough to be resolved in the light
microscope but are generally not visible as they lack contrast. Special stains are used to
make them visible, for e.g. Janus Green B.
Each cell contains hundreds to thousands of mitochondria (e.g., the liver cell contains 1000-
2000 mitochondria occupying one fifth of the cell volume). Mitochonria are double
membrane organelles. Their number and size varies in metabolically different cells. The
mitochondria are highly plastic and constantly change their shape and position. In some
cells, however, they remain in a fixed position and provide ATP, e.g., the muscle cells and
around the flagellum of a sperm.
Figure: The Electron micrograph of normal adult muscle showing mitochondria (arrows).
Source:http://missinglink.ucsf.edu/lm/ids_104_musclenerve_path/student_musclen
erve/normal2.html
Mitochondria
Institute of Lifelong Learning, University of Delhi 3
Mitochondria have their own circular DNA and synthesize some of their proteins. Thus, they
are said to be “semi-autonomous” organelles. Most of the proteins required by the
mitochondria, however, are encoded by the nuclear genes and are imported from the
cytosol. The organelle is believed to have originated by the process of endosymbiosis.
Historical Background
1894- Richard Altmann, discovered the cell organelle and called it as "bioblasts”.
1898- Carl Benda coined the term "mitochondria". The word mitochondrion is derived from
the Greek word mitos- thread, and chondrion- granule.
1900 – L. Michaelis (of enzyme kinetics) found that mitochondria in living cells could be
specifically stained green by the dye ‘Janus Green B’. Because the dye must be oxidized to
give the green colour, Michaelis proposed that mitochondria are cellular oxidizing organelles.
1904- Friedrich Meves for the first time observed mitochondria in plants (Nymphaea alba).
1908- Friedrich Meves and Claudius Regaud suggested that proteins and lipids are present
in mitochondria.
1912- B. F. Kingsbury related this organelle with cell respiration.
1913- O.H.Warburg extracted particles from guinea-pig liver and conformed that enzymes
catalyzing oxidative reactions are present in the particles identified as mitochondria, and
thus, linked them to respiration.
1925- David Keilin discovered cytochromes in mitochondria.
1937 – Based on work of many scientists such as Szent-Gyorgyi, Martius, Knoop and others
and his own work, Hans Krebs presented the complete tricarboxylic acid cycle and was
awarded a Nobel prize in 1953.
1939- It was demonstrated that in minced muscle cells one molecule of oxygen can lead to
formation of two ATP.
Page 5
Electron Mitochondria
Institute of Lifelong Learning, University of Delhi
Lesson: Electron Mitochondria
Lesson Developer: Renu Kathpalia
College/Department: Kirori Mal College, University of Delhi
Mitochondria
Institute of Lifelong Learning, University of Delhi 1
Table of Contents
Chapter: Mitochondria
? Introduction
? Historical Background
? Size and number
? Morphology
o The outer membrane
o The innermembrane
o The inter membrane space
o Matrix
? Mitochondrial DNA
? Mitochondrial Biogenesis
? Marker Enzymes
? Functions of mitochondria
? Cellular respiration
? Glycolysis
? Kerb’s cycle
? Oxidative phosphorylation
? Electron transport chain
? Chemiosmotic coupling
? Role in apoptosis
? Cell specific functions
? Endosymbiotic origin of mitochondria
? Import of proteins into mitochondria
? Summary
? Exercise/ Practice
? Glossary
? References/ Bibliography/ Further Reading
Mitochondria
Institute of Lifelong Learning, University of Delhi 2
Introduction
In eukaryotic cells most of the generation of metabolic energy occurs in the organelle called
mitochondria (singular: mitochondrion) often referred to as the power house of the cell.
The energy is derived by the breakdown of carbohydrates, amino acids and fatty acids and
is used in the formation of energy rich molecules the ATP (often referred to as the energy
currency of the cell) by the process of oxidative phosphorylation.
Mitochondria are found in the cytoplasm of nearly all eukaryotic cells and occupy a
substantial portion of the cytoplasm. They are large enough to be resolved in the light
microscope but are generally not visible as they lack contrast. Special stains are used to
make them visible, for e.g. Janus Green B.
Each cell contains hundreds to thousands of mitochondria (e.g., the liver cell contains 1000-
2000 mitochondria occupying one fifth of the cell volume). Mitochonria are double
membrane organelles. Their number and size varies in metabolically different cells. The
mitochondria are highly plastic and constantly change their shape and position. In some
cells, however, they remain in a fixed position and provide ATP, e.g., the muscle cells and
around the flagellum of a sperm.
Figure: The Electron micrograph of normal adult muscle showing mitochondria (arrows).
Source:http://missinglink.ucsf.edu/lm/ids_104_musclenerve_path/student_musclen
erve/normal2.html
Mitochondria
Institute of Lifelong Learning, University of Delhi 3
Mitochondria have their own circular DNA and synthesize some of their proteins. Thus, they
are said to be “semi-autonomous” organelles. Most of the proteins required by the
mitochondria, however, are encoded by the nuclear genes and are imported from the
cytosol. The organelle is believed to have originated by the process of endosymbiosis.
Historical Background
1894- Richard Altmann, discovered the cell organelle and called it as "bioblasts”.
1898- Carl Benda coined the term "mitochondria". The word mitochondrion is derived from
the Greek word mitos- thread, and chondrion- granule.
1900 – L. Michaelis (of enzyme kinetics) found that mitochondria in living cells could be
specifically stained green by the dye ‘Janus Green B’. Because the dye must be oxidized to
give the green colour, Michaelis proposed that mitochondria are cellular oxidizing organelles.
1904- Friedrich Meves for the first time observed mitochondria in plants (Nymphaea alba).
1908- Friedrich Meves and Claudius Regaud suggested that proteins and lipids are present
in mitochondria.
1912- B. F. Kingsbury related this organelle with cell respiration.
1913- O.H.Warburg extracted particles from guinea-pig liver and conformed that enzymes
catalyzing oxidative reactions are present in the particles identified as mitochondria, and
thus, linked them to respiration.
1925- David Keilin discovered cytochromes in mitochondria.
1937 – Based on work of many scientists such as Szent-Gyorgyi, Martius, Knoop and others
and his own work, Hans Krebs presented the complete tricarboxylic acid cycle and was
awarded a Nobel prize in 1953.
1939- It was demonstrated that in minced muscle cells one molecule of oxygen can lead to
formation of two ATP.
Mitochondria
Institute of Lifelong Learning, University of Delhi 4
1941- F.A.Lipmann gave the Unifying concept of ATP as the energy currency or the primary
and universal carrier of chemical energy in cells. energy rich phosphate bond in cellular
metabolism. He shared the Nobel prize with Krebs in 1953.
1946- A.Claude isolated mitochondria from other cell fraction and did biochemical analysis.
He also isolated cytochrome oxidase and other enzymes responsible for the respiratory
chain.
1956 – George Palade and Fritjof Sjostrand published high resolution electron micrographs
showing the presence of two mitochondrial membranes and the cristae formed by the folded
inner mitochondrial membrane.
1957- Philip Siekevitz named the mitochondria as "the powerhouse of the cell", because it
generates adenosine triphosphate (ATP).
1960- Efraim Racker gave evidence for presence of particles involved in coupling ATP
synthesis to electron transport and called them coupling factors or F1 particles.
1961- Peter D. Mitchell proposed the chemi-osmotic mechanism to explain biosynthesis of
ATP and was awarded a Nobel prize in 1978.
1964 – H. Fernandez-Moran – presented electron micrographs of negatively stained inner
mitochondrial membrane containing sub-mitochondrial particles which he named as
“elementary particles”.
1967- Ribosomes were isolated from mitochondria.
1968- The mapping of mitochondrial genes was done.
1976- The complete genetic and physical map of yeast mitochondria was developed.
1978- Peter Mitchell was awarded noble prize for proposing chemiosmotic mechanism of
oxidative phosphorylation.
Size and number
Read More