Lecture 9 - Mitochondrial electron transport | Plant Metabolism - Botany PDF Download

 Page 1


Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
0 
       
 
 
Lesson Prepared under MHRD project “National 
Mission on Education Through ICT” 
 
Discipline: Botany 
Paper: Plant Metabolism 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Mitochondrial Electron Transport 
 
Lesson Developer: Dr. Manju A. Lal  
Department of Botany,  
Kirori Mal College, University of Delhi 
 
Lesson Reviewer: Prof. S.C. Bhatla, Department of Botany, 
University of Delhi 
 
Language Editor: Namrata Dhaka 
Department/College: Department of Genetics, University of 
Delhi, South Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
 
 
 
 
Page 2


Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
0 
       
 
 
Lesson Prepared under MHRD project “National 
Mission on Education Through ICT” 
 
Discipline: Botany 
Paper: Plant Metabolism 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Mitochondrial Electron Transport 
 
Lesson Developer: Dr. Manju A. Lal  
Department of Botany,  
Kirori Mal College, University of Delhi 
 
Lesson Reviewer: Prof. S.C. Bhatla, Department of Botany, 
University of Delhi 
 
Language Editor: Namrata Dhaka 
Department/College: Department of Genetics, University of 
Delhi, South Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
 
 
 
 
Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
1 
Chapter: Mitochondrial electron transport 
Table of Contents 
? Introduction 
? Principle behind electron transport through 
ETC 
? Standard reduction potential of a reaction 
? Calculation of standard free energy change during 
a reaction 
? Electron Transport Chain 
? Components of ETC 
? Sequence of electron carriers in ETC 
? Composition of the complexes 
? Complex I NADH UQ Oxidoreductase 
? Complex II Succinate-Ubiquinone 
Oxidoreductase 
? Complex III Ubiquinone-Cyt c 
Oxidoreductase 
? Complex IV Cytochrome c oxidase 
? Coupling of electron transport with proton 
gradient 
? Q-cycle 
? Unique features of mitochondrial electron 
transport in plants 
? External NADH/NADPH dehydrogenase 
? Internal Rotenone insensitive NADH 
dehydrogenase 
? Alternate Oxidase 
? Role of cyanide resistant respiration in plant 
metabolism 
? Cofactors associated with enzymes of 
respiratory chain 
? NAD+/NADP+ 
? FAD/FMN 
? Ubiquinone 
? Cytochromes 
Page 3


Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
0 
       
 
 
Lesson Prepared under MHRD project “National 
Mission on Education Through ICT” 
 
Discipline: Botany 
Paper: Plant Metabolism 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Mitochondrial Electron Transport 
 
Lesson Developer: Dr. Manju A. Lal  
Department of Botany,  
Kirori Mal College, University of Delhi 
 
Lesson Reviewer: Prof. S.C. Bhatla, Department of Botany, 
University of Delhi 
 
Language Editor: Namrata Dhaka 
Department/College: Department of Genetics, University of 
Delhi, South Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
 
 
 
 
Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
1 
Chapter: Mitochondrial electron transport 
Table of Contents 
? Introduction 
? Principle behind electron transport through 
ETC 
? Standard reduction potential of a reaction 
? Calculation of standard free energy change during 
a reaction 
? Electron Transport Chain 
? Components of ETC 
? Sequence of electron carriers in ETC 
? Composition of the complexes 
? Complex I NADH UQ Oxidoreductase 
? Complex II Succinate-Ubiquinone 
Oxidoreductase 
? Complex III Ubiquinone-Cyt c 
Oxidoreductase 
? Complex IV Cytochrome c oxidase 
? Coupling of electron transport with proton 
gradient 
? Q-cycle 
? Unique features of mitochondrial electron 
transport in plants 
? External NADH/NADPH dehydrogenase 
? Internal Rotenone insensitive NADH 
dehydrogenase 
? Alternate Oxidase 
? Role of cyanide resistant respiration in plant 
metabolism 
? Cofactors associated with enzymes of 
respiratory chain 
? NAD+/NADP+ 
? FAD/FMN 
? Ubiquinone 
? Cytochromes 
Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
2 
? Rieske proteins 
? Environmental factors affecting rate of 
respiration 
? Temperature 
? Oxygen 
? Carbon dioxide 
? Summary 
? Exercises 
? Web links 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Page 4


Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
0 
       
 
 
Lesson Prepared under MHRD project “National 
Mission on Education Through ICT” 
 
Discipline: Botany 
Paper: Plant Metabolism 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Mitochondrial Electron Transport 
 
Lesson Developer: Dr. Manju A. Lal  
Department of Botany,  
Kirori Mal College, University of Delhi 
 
Lesson Reviewer: Prof. S.C. Bhatla, Department of Botany, 
University of Delhi 
 
Language Editor: Namrata Dhaka 
Department/College: Department of Genetics, University of 
Delhi, South Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
 
 
 
 
Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
1 
Chapter: Mitochondrial electron transport 
Table of Contents 
? Introduction 
? Principle behind electron transport through 
ETC 
? Standard reduction potential of a reaction 
? Calculation of standard free energy change during 
a reaction 
? Electron Transport Chain 
? Components of ETC 
? Sequence of electron carriers in ETC 
? Composition of the complexes 
? Complex I NADH UQ Oxidoreductase 
? Complex II Succinate-Ubiquinone 
Oxidoreductase 
? Complex III Ubiquinone-Cyt c 
Oxidoreductase 
? Complex IV Cytochrome c oxidase 
? Coupling of electron transport with proton 
gradient 
? Q-cycle 
? Unique features of mitochondrial electron 
transport in plants 
? External NADH/NADPH dehydrogenase 
? Internal Rotenone insensitive NADH 
dehydrogenase 
? Alternate Oxidase 
? Role of cyanide resistant respiration in plant 
metabolism 
? Cofactors associated with enzymes of 
respiratory chain 
? NAD+/NADP+ 
? FAD/FMN 
? Ubiquinone 
? Cytochromes 
Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
2 
? Rieske proteins 
? Environmental factors affecting rate of 
respiration 
? Temperature 
? Oxygen 
? Carbon dioxide 
? Summary 
? Exercises 
? Web links 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
3 
Learning outcomes 
After reading this lesson, the readers should be able to understand the following: 
? The principle involved in the movement of electrons through Electron 
transport chain. 
? The complexes of the electron transport chain of mitochondria and their 
components. 
? The unique features of e
-
 transport in plants. 
? The cyanide resistant respiration in plants. 
 
 
Introduction 
In the previous lesson you have studied how glucose molecule is catabolized to 
pyruvate. Fate of pyruvate is determined by the presence or absence of O
2
. In 
case O
2
 is absent, pyruvate is metabolized by fermentation in the cytosol. During 
fermentation NADH produced via glycolysis is reoxidized to NAD
+
 and glycolysis 
thus continues to operate. However, in presence of O
2
, both pyruvate and NADH 
are translocated to mitochondria. NADH is not translocated directly through the 
inner mitochondrial membrane, since the membrane is impermeable to NADH. It 
is the reducing equivalents of NADH, which are transported in the form of malate 
or other forms, which we have already discussed in the previous lesson. There 
are pyruvate translocators in the inner mitochondrial membrane, which transport 
pyruvate in exchange of OH
- 
ions, where it is further metabolized by oxidative 
decarboxylation and TCA cycle. Ultimately all the three carbons of the pyruvate 
are lost as CO
2
 and 4 NADH and 1 FADH
2 
molecules are produced during the 
process, besides the production of one ATP/GTP.  
Page 5


Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
0 
       
 
 
Lesson Prepared under MHRD project “National 
Mission on Education Through ICT” 
 
Discipline: Botany 
Paper: Plant Metabolism 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Mitochondrial Electron Transport 
 
Lesson Developer: Dr. Manju A. Lal  
Department of Botany,  
Kirori Mal College, University of Delhi 
 
Lesson Reviewer: Prof. S.C. Bhatla, Department of Botany, 
University of Delhi 
 
Language Editor: Namrata Dhaka 
Department/College: Department of Genetics, University of 
Delhi, South Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
 
 
 
 
Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
1 
Chapter: Mitochondrial electron transport 
Table of Contents 
? Introduction 
? Principle behind electron transport through 
ETC 
? Standard reduction potential of a reaction 
? Calculation of standard free energy change during 
a reaction 
? Electron Transport Chain 
? Components of ETC 
? Sequence of electron carriers in ETC 
? Composition of the complexes 
? Complex I NADH UQ Oxidoreductase 
? Complex II Succinate-Ubiquinone 
Oxidoreductase 
? Complex III Ubiquinone-Cyt c 
Oxidoreductase 
? Complex IV Cytochrome c oxidase 
? Coupling of electron transport with proton 
gradient 
? Q-cycle 
? Unique features of mitochondrial electron 
transport in plants 
? External NADH/NADPH dehydrogenase 
? Internal Rotenone insensitive NADH 
dehydrogenase 
? Alternate Oxidase 
? Role of cyanide resistant respiration in plant 
metabolism 
? Cofactors associated with enzymes of 
respiratory chain 
? NAD+/NADP+ 
? FAD/FMN 
? Ubiquinone 
? Cytochromes 
Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
2 
? Rieske proteins 
? Environmental factors affecting rate of 
respiration 
? Temperature 
? Oxygen 
? Carbon dioxide 
? Summary 
? Exercises 
? Web links 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
3 
Learning outcomes 
After reading this lesson, the readers should be able to understand the following: 
? The principle involved in the movement of electrons through Electron 
transport chain. 
? The complexes of the electron transport chain of mitochondria and their 
components. 
? The unique features of e
-
 transport in plants. 
? The cyanide resistant respiration in plants. 
 
 
Introduction 
In the previous lesson you have studied how glucose molecule is catabolized to 
pyruvate. Fate of pyruvate is determined by the presence or absence of O
2
. In 
case O
2
 is absent, pyruvate is metabolized by fermentation in the cytosol. During 
fermentation NADH produced via glycolysis is reoxidized to NAD
+
 and glycolysis 
thus continues to operate. However, in presence of O
2
, both pyruvate and NADH 
are translocated to mitochondria. NADH is not translocated directly through the 
inner mitochondrial membrane, since the membrane is impermeable to NADH. It 
is the reducing equivalents of NADH, which are transported in the form of malate 
or other forms, which we have already discussed in the previous lesson. There 
are pyruvate translocators in the inner mitochondrial membrane, which transport 
pyruvate in exchange of OH
- 
ions, where it is further metabolized by oxidative 
decarboxylation and TCA cycle. Ultimately all the three carbons of the pyruvate 
are lost as CO
2
 and 4 NADH and 1 FADH
2 
molecules are produced during the 
process, besides the production of one ATP/GTP.  
Mitochondrial Electron Transport 
 
Institute of Lifelong learning, University of Delhi, South Campus 
4 
 
Figure: Fate of pyruvate in aerobic and anaerobic organisms 
Source: http://2012books.lardbucket.org/books/introduction-to-chemistry-
general-organic-and-biological/s23-energy-metabolism.html(cc) 
 
Figure: Production of ATP via fermentation 
Source:http://en.wikipedia.org/wiki/Fermentation#mediaviewer/File:Ethanol_fer
mentation-1.svg(cc)