Lecture 16 - Intermediary Metabolism | Plant Metabolism - Botany PDF Download

 Page 1


 
                    Institute of Lifelong Learning, University of Delhi                             1 
 
                                                                                              
 
Lesson Prepared under MHRD project “National Mission 
on Education through ICT” 
Discipline: Botany 
Paper: Plant Metabolism 
National Coordinator: Prof. S.C. Bhatla 
Lesson: Intermediary Metabolism 
Lesson Developer: Dhara Arora 
Department/College: Department of Botany, University 
of Delhi 
Lesson Reviewer: 
Department/College: 
Language Editor: Vinee Khanna 
Department/College: Department of Genetics, University 
of Delhi South Campus. 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
Page 2


 
                    Institute of Lifelong Learning, University of Delhi                             1 
 
                                                                                              
 
Lesson Prepared under MHRD project “National Mission 
on Education through ICT” 
Discipline: Botany 
Paper: Plant Metabolism 
National Coordinator: Prof. S.C. Bhatla 
Lesson: Intermediary Metabolism 
Lesson Developer: Dhara Arora 
Department/College: Department of Botany, University 
of Delhi 
Lesson Reviewer: 
Department/College: 
Language Editor: Vinee Khanna 
Department/College: Department of Genetics, University 
of Delhi South Campus. 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
                    Institute of Lifelong Learning, University of Delhi                             2 
Table of contents 
Intermediary Metabolism 
? Introduction 
? Intermediary metabolism 
? Catabolism and anabolism 
? Interrelationship of metabolism 
? Conversion of fats and proteins to glucose 
? Conversion of proteins to fats 
? Conversion of glucose to proteins  
? Conversion of glucose to fats 
? Linked pathways due to common intermediates pools 
? Summary 
? Exercise/ Practice 
? Glossary 
? References/ Further Reading 
? Weblinks 
 
 
 
 
 
 
 
 
 
 
 
Page 3


 
                    Institute of Lifelong Learning, University of Delhi                             1 
 
                                                                                              
 
Lesson Prepared under MHRD project “National Mission 
on Education through ICT” 
Discipline: Botany 
Paper: Plant Metabolism 
National Coordinator: Prof. S.C. Bhatla 
Lesson: Intermediary Metabolism 
Lesson Developer: Dhara Arora 
Department/College: Department of Botany, University 
of Delhi 
Lesson Reviewer: 
Department/College: 
Language Editor: Vinee Khanna 
Department/College: Department of Genetics, University 
of Delhi South Campus. 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
                    Institute of Lifelong Learning, University of Delhi                             2 
Table of contents 
Intermediary Metabolism 
? Introduction 
? Intermediary metabolism 
? Catabolism and anabolism 
? Interrelationship of metabolism 
? Conversion of fats and proteins to glucose 
? Conversion of proteins to fats 
? Conversion of glucose to proteins  
? Conversion of glucose to fats 
? Linked pathways due to common intermediates pools 
? Summary 
? Exercise/ Practice 
? Glossary 
? References/ Further Reading 
? Weblinks 
 
 
 
 
 
 
 
 
 
 
 
 
                    Institute of Lifelong Learning, University of Delhi                             3 
 
Learning outcomes: 
The student will be able to 
? Understand what is intermediary metabolism 
? Become familiar with the concept of metabolic maps 
? Differentiate between anabolism and catabolism 
? Describe terms like glycolysis, gluconeogenesis, glyoxylate cycle, glucogenic 
amino acids 
? Explain why metabolic pathways are not considered as closed systems 
? Discuss the ways in which carbohydrate metabolic pathways, glycolysis and the 
citric acid cycle interrelate with protein and lipid metabolic pathways 
? Understand the linked metabolic pathways of fatty acid synthesis and protein 
synthesis with carbohydrates and their derived substrates  
? Appreciate the existence of common metabolic pools in cells  
 
 
Page 4


 
                    Institute of Lifelong Learning, University of Delhi                             1 
 
                                                                                              
 
Lesson Prepared under MHRD project “National Mission 
on Education through ICT” 
Discipline: Botany 
Paper: Plant Metabolism 
National Coordinator: Prof. S.C. Bhatla 
Lesson: Intermediary Metabolism 
Lesson Developer: Dhara Arora 
Department/College: Department of Botany, University 
of Delhi 
Lesson Reviewer: 
Department/College: 
Language Editor: Vinee Khanna 
Department/College: Department of Genetics, University 
of Delhi South Campus. 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
                    Institute of Lifelong Learning, University of Delhi                             2 
Table of contents 
Intermediary Metabolism 
? Introduction 
? Intermediary metabolism 
? Catabolism and anabolism 
? Interrelationship of metabolism 
? Conversion of fats and proteins to glucose 
? Conversion of proteins to fats 
? Conversion of glucose to proteins  
? Conversion of glucose to fats 
? Linked pathways due to common intermediates pools 
? Summary 
? Exercise/ Practice 
? Glossary 
? References/ Further Reading 
? Weblinks 
 
 
 
 
 
 
 
 
 
 
 
 
                    Institute of Lifelong Learning, University of Delhi                             3 
 
Learning outcomes: 
The student will be able to 
? Understand what is intermediary metabolism 
? Become familiar with the concept of metabolic maps 
? Differentiate between anabolism and catabolism 
? Describe terms like glycolysis, gluconeogenesis, glyoxylate cycle, glucogenic 
amino acids 
? Explain why metabolic pathways are not considered as closed systems 
? Discuss the ways in which carbohydrate metabolic pathways, glycolysis and the 
citric acid cycle interrelate with protein and lipid metabolic pathways 
? Understand the linked metabolic pathways of fatty acid synthesis and protein 
synthesis with carbohydrates and their derived substrates  
? Appreciate the existence of common metabolic pools in cells  
 
 
 
                    Institute of Lifelong Learning, University of Delhi                             4 
Introduction 
The word 'metabolism' is derived from the Greek word for "change". Metabolism is the 
sum of all processes by which biomolecules are broken down and resynthesized to form 
a complex, in a highly regulated network of interdependent enzymatic reactions. 
Metabolism consists of hundreds of organized enzymatic reactions proceeding in a 
stepwise fashion to transform substrates into end products through many specific 
chemical intermediates. To reflect this aspect of metabolism, metabolism is sometimes 
referred to as intermediary metabolism. Virtually all of the principal reactions of the 
intermediary metabolism of carbohydrates, lipids, amino acids, nucleotides and their 
derivatives are depicted on metabolic maps. Each intermediate is represented as a 
black dot and each enzyme as a line in these metabolic maps.  
 
Figure: A metabolic map as a set of dots and lines depicting carbohydrate metabolism. 
Source: http://images-mediawiki-sites.thefullwiki.org/03/2/3/1/7720179557577639.gif 
Page 5


 
                    Institute of Lifelong Learning, University of Delhi                             1 
 
                                                                                              
 
Lesson Prepared under MHRD project “National Mission 
on Education through ICT” 
Discipline: Botany 
Paper: Plant Metabolism 
National Coordinator: Prof. S.C. Bhatla 
Lesson: Intermediary Metabolism 
Lesson Developer: Dhara Arora 
Department/College: Department of Botany, University 
of Delhi 
Lesson Reviewer: 
Department/College: 
Language Editor: Vinee Khanna 
Department/College: Department of Genetics, University 
of Delhi South Campus. 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
                    Institute of Lifelong Learning, University of Delhi                             2 
Table of contents 
Intermediary Metabolism 
? Introduction 
? Intermediary metabolism 
? Catabolism and anabolism 
? Interrelationship of metabolism 
? Conversion of fats and proteins to glucose 
? Conversion of proteins to fats 
? Conversion of glucose to proteins  
? Conversion of glucose to fats 
? Linked pathways due to common intermediates pools 
? Summary 
? Exercise/ Practice 
? Glossary 
? References/ Further Reading 
? Weblinks 
 
 
 
 
 
 
 
 
 
 
 
 
                    Institute of Lifelong Learning, University of Delhi                             3 
 
Learning outcomes: 
The student will be able to 
? Understand what is intermediary metabolism 
? Become familiar with the concept of metabolic maps 
? Differentiate between anabolism and catabolism 
? Describe terms like glycolysis, gluconeogenesis, glyoxylate cycle, glucogenic 
amino acids 
? Explain why metabolic pathways are not considered as closed systems 
? Discuss the ways in which carbohydrate metabolic pathways, glycolysis and the 
citric acid cycle interrelate with protein and lipid metabolic pathways 
? Understand the linked metabolic pathways of fatty acid synthesis and protein 
synthesis with carbohydrates and their derived substrates  
? Appreciate the existence of common metabolic pools in cells  
 
 
 
                    Institute of Lifelong Learning, University of Delhi                             4 
Introduction 
The word 'metabolism' is derived from the Greek word for "change". Metabolism is the 
sum of all processes by which biomolecules are broken down and resynthesized to form 
a complex, in a highly regulated network of interdependent enzymatic reactions. 
Metabolism consists of hundreds of organized enzymatic reactions proceeding in a 
stepwise fashion to transform substrates into end products through many specific 
chemical intermediates. To reflect this aspect of metabolism, metabolism is sometimes 
referred to as intermediary metabolism. Virtually all of the principal reactions of the 
intermediary metabolism of carbohydrates, lipids, amino acids, nucleotides and their 
derivatives are depicted on metabolic maps. Each intermediate is represented as a 
black dot and each enzyme as a line in these metabolic maps.  
 
Figure: A metabolic map as a set of dots and lines depicting carbohydrate metabolism. 
Source: http://images-mediawiki-sites.thefullwiki.org/03/2/3/1/7720179557577639.gif 
 
                    Institute of Lifelong Learning, University of Delhi                             5 
Marked similarity is found in the major pathways of metabolism in organisms, providing 
strong evidence that all life has descended from a common ancestral form. For example, 
the metabolic pathway in which energy is released from glucose and captured in the 
form of ATP, called glycolysis, operates in almost every cell. Amidst this similarity in 
the basic set of central metabolic pathways, different cells are characterized by the 
alternative pathways they might express. There exists a wide range of metabolic 
possibilities.  
The flow of energy in the biosphere is tightly coupled with carbon and oxygen cycles. 
Light energy is utilized by photoautotrophs to form organic molecules like carbohydrates 
from atmospheric carbon dioxide and water. These organic products are then used by 
heterotrophic cells as fuels and as building blocks, for the synthesis of their own unique 
set of biomolecules. The end product of heterotrophic carbon metabolism is CO
2
 which is 
returned to the atmosphere for reuse by the photoautotrophs. There are three 
intermediates responsible for linking the major metabolic pathways. These are 
? Acetyl-CoA 
? Pyruvate 
? NADH