Lecture 13 - Mitochondria | Cell Biology- Botany PDF Download

 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