Lecture 1 - Concepts of metabolism | Plant Metabolism - Botany PDF Download

 Page 1


Concepts of Metabolism 
 
Institute if 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, Department of Botany, University 
of Delhi 
Lesson: Concept of metabolism 
Lesson Developer: Dr. Misha Yadav 
Department/College: Shivaji College, University of Delhi 
Lesson Reviewer: Dr. Manju Lal 
Department/College: Kirori Mal 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


Concepts of Metabolism 
 
Institute if 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, Department of Botany, University 
of Delhi 
Lesson: Concept of metabolism 
Lesson Developer: Dr. Misha Yadav 
Department/College: Shivaji College, University of Delhi 
Lesson Reviewer: Dr. Manju Lal 
Department/College: Kirori Mal College 
Language Editor: Vinee Khanna 
Department/College: Department of Genetics, University of Delhi South 
Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
  
Concepts of Metabolism 
 
Institute if Lifelong learning, University of Delhi                                                                                                  2 
Table of Contents 
Chapter: Concepts of Metabolism 
? Introduction  
? Metabolism: basic concepts 
? Anabolism 
? Catabolism 
? Amphibolic pathways 
? Free energy changes and coupled reactions  
? Energy coupled reactions 
? ATP: energy currency of cell  
? Oxidation-reduction coupled reactions 
? Regulation of Metabolism 
? Controlling the amount of enzyme 
? Controlling the catalytic activity of enzyme 
? Allosteric control 
? Covalent modulation 
? Isozymes 
? Compartmentalization of enzymes 
? Separation of anabolic and catabolic pathways 
? Summary 
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
? Weblinks 
 
 
 
  
Page 3


Concepts of Metabolism 
 
Institute if 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, Department of Botany, University 
of Delhi 
Lesson: Concept of metabolism 
Lesson Developer: Dr. Misha Yadav 
Department/College: Shivaji College, University of Delhi 
Lesson Reviewer: Dr. Manju Lal 
Department/College: Kirori Mal College 
Language Editor: Vinee Khanna 
Department/College: Department of Genetics, University of Delhi South 
Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
  
Concepts of Metabolism 
 
Institute if Lifelong learning, University of Delhi                                                                                                  2 
Table of Contents 
Chapter: Concepts of Metabolism 
? Introduction  
? Metabolism: basic concepts 
? Anabolism 
? Catabolism 
? Amphibolic pathways 
? Free energy changes and coupled reactions  
? Energy coupled reactions 
? ATP: energy currency of cell  
? Oxidation-reduction coupled reactions 
? Regulation of Metabolism 
? Controlling the amount of enzyme 
? Controlling the catalytic activity of enzyme 
? Allosteric control 
? Covalent modulation 
? Isozymes 
? Compartmentalization of enzymes 
? Separation of anabolic and catabolic pathways 
? Summary 
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
? Weblinks 
 
 
 
  
Concepts of Metabolism 
 
Institute if Lifelong learning, University of Delhi                                                                                                  3 
Introduction 
Cells are open systems which intake food in the form of carbohydrates, lipids and proteins, 
water, gases such as O
2
. Mere presence of biomolecules and other necessary components 
inside a cell are not enough to make it ‘living’. Occurrence of metabolic pathways inside a 
cell is vital to its existence and sustenance. Metabolism allows the cells to synthesize and 
catabolize molecules as per their requirements, thus making it truly living. In every cell 
various biomolecules are broken down and others are synthesized in different pathways, 
forming a complex but highly regulated network of reactions. After understanding the 
chemical composition and structure of biomolecules, it is very important to know how are 
they synthesized and thenmetabolized inside the cells to carry out the normal functioning of 
cell/organism. We must therefore study the basic concepts governing the metabolic 
pathways. 
 
 
 
Page 4


Concepts of Metabolism 
 
Institute if 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, Department of Botany, University 
of Delhi 
Lesson: Concept of metabolism 
Lesson Developer: Dr. Misha Yadav 
Department/College: Shivaji College, University of Delhi 
Lesson Reviewer: Dr. Manju Lal 
Department/College: Kirori Mal College 
Language Editor: Vinee Khanna 
Department/College: Department of Genetics, University of Delhi South 
Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
  
Concepts of Metabolism 
 
Institute if Lifelong learning, University of Delhi                                                                                                  2 
Table of Contents 
Chapter: Concepts of Metabolism 
? Introduction  
? Metabolism: basic concepts 
? Anabolism 
? Catabolism 
? Amphibolic pathways 
? Free energy changes and coupled reactions  
? Energy coupled reactions 
? ATP: energy currency of cell  
? Oxidation-reduction coupled reactions 
? Regulation of Metabolism 
? Controlling the amount of enzyme 
? Controlling the catalytic activity of enzyme 
? Allosteric control 
? Covalent modulation 
? Isozymes 
? Compartmentalization of enzymes 
? Separation of anabolic and catabolic pathways 
? Summary 
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
? Weblinks 
 
 
 
  
Concepts of Metabolism 
 
Institute if Lifelong learning, University of Delhi                                                                                                  3 
Introduction 
Cells are open systems which intake food in the form of carbohydrates, lipids and proteins, 
water, gases such as O
2
. Mere presence of biomolecules and other necessary components 
inside a cell are not enough to make it ‘living’. Occurrence of metabolic pathways inside a 
cell is vital to its existence and sustenance. Metabolism allows the cells to synthesize and 
catabolize molecules as per their requirements, thus making it truly living. In every cell 
various biomolecules are broken down and others are synthesized in different pathways, 
forming a complex but highly regulated network of reactions. After understanding the 
chemical composition and structure of biomolecules, it is very important to know how are 
they synthesized and thenmetabolized inside the cells to carry out the normal functioning of 
cell/organism. We must therefore study the basic concepts governing the metabolic 
pathways. 
 
 
 
Concepts of Metabolism 
 
Institute if Lifelong learning, University of Delhi                                                                                                  4 
Figure: The concept of catabolism and anabolism  
Source:http://chemwiki.ucdavis.edu/Biological_Chemistry/Metabolism 
Metabolism: basic concepts 
A series of consecutive chemical reactions occurring in an organized and ordered manner 
considered together constitute a metabolic pathway. The tremendous diversity of metabolic 
processes allows the organism to perform all the normal life processes such as growth, 
reproduction, maintenance of cell structures, repair damage and respond to environment. 
Metabolic pathways do not occur at random inside the cells. These are involved in 
performing specific functions such as breakdown of glucose or its synthesis, synthesis of 
ATP etc. These pathways are series of highly regulated, branched, interconnected enzymatic 
reactions, which have specific reactants and products.  
 
 
Figure: Schematic representation of major metabolic pathways 
Page 5


Concepts of Metabolism 
 
Institute if 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, Department of Botany, University 
of Delhi 
Lesson: Concept of metabolism 
Lesson Developer: Dr. Misha Yadav 
Department/College: Shivaji College, University of Delhi 
Lesson Reviewer: Dr. Manju Lal 
Department/College: Kirori Mal College 
Language Editor: Vinee Khanna 
Department/College: Department of Genetics, University of Delhi South 
Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
  
Concepts of Metabolism 
 
Institute if Lifelong learning, University of Delhi                                                                                                  2 
Table of Contents 
Chapter: Concepts of Metabolism 
? Introduction  
? Metabolism: basic concepts 
? Anabolism 
? Catabolism 
? Amphibolic pathways 
? Free energy changes and coupled reactions  
? Energy coupled reactions 
? ATP: energy currency of cell  
? Oxidation-reduction coupled reactions 
? Regulation of Metabolism 
? Controlling the amount of enzyme 
? Controlling the catalytic activity of enzyme 
? Allosteric control 
? Covalent modulation 
? Isozymes 
? Compartmentalization of enzymes 
? Separation of anabolic and catabolic pathways 
? Summary 
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
? Weblinks 
 
 
 
  
Concepts of Metabolism 
 
Institute if Lifelong learning, University of Delhi                                                                                                  3 
Introduction 
Cells are open systems which intake food in the form of carbohydrates, lipids and proteins, 
water, gases such as O
2
. Mere presence of biomolecules and other necessary components 
inside a cell are not enough to make it ‘living’. Occurrence of metabolic pathways inside a 
cell is vital to its existence and sustenance. Metabolism allows the cells to synthesize and 
catabolize molecules as per their requirements, thus making it truly living. In every cell 
various biomolecules are broken down and others are synthesized in different pathways, 
forming a complex but highly regulated network of reactions. After understanding the 
chemical composition and structure of biomolecules, it is very important to know how are 
they synthesized and thenmetabolized inside the cells to carry out the normal functioning of 
cell/organism. We must therefore study the basic concepts governing the metabolic 
pathways. 
 
 
 
Concepts of Metabolism 
 
Institute if Lifelong learning, University of Delhi                                                                                                  4 
Figure: The concept of catabolism and anabolism  
Source:http://chemwiki.ucdavis.edu/Biological_Chemistry/Metabolism 
Metabolism: basic concepts 
A series of consecutive chemical reactions occurring in an organized and ordered manner 
considered together constitute a metabolic pathway. The tremendous diversity of metabolic 
processes allows the organism to perform all the normal life processes such as growth, 
reproduction, maintenance of cell structures, repair damage and respond to environment. 
Metabolic pathways do not occur at random inside the cells. These are involved in 
performing specific functions such as breakdown of glucose or its synthesis, synthesis of 
ATP etc. These pathways are series of highly regulated, branched, interconnected enzymatic 
reactions, which have specific reactants and products.  
 
 
Figure: Schematic representation of major metabolic pathways 
Concepts of Metabolism 
 
Institute if Lifelong learning, University of Delhi                                                                                                  5 
Source:https://adapaproject.org/bbk/tiki-
index.php?page=Leaf%3A+What+is+the+difference+between+metabolism%2C+catabolis
m%2C+and+anabolism%3F 
Usually, inside a cell more than 2000 metabolic reactions are known to occur, each reaction 
having a specific enzyme for catalysis. Two or more pathways occurring in a cell can have 
certain reactions common to them. This links the various pathways inside the cell. Some 
well known common examples are glycolysis, citric acid cyclic, gluconeogenesis, 
photosynthesis.  Many pathways are common to all cells whereas other may be specific to 
certain cells only. The type of metabolic pathways occurring in an organism depends on the 
type of organism, its nutritional status and the developmental stage attained by it. It may 
also vary depending upon the type of cell within an organism. 
Characteristics of metabolic pathways: 
? These are irreversible. 
? The first reaction step of pathway is a committed step. 
? Some of the steps in a metabolic pathway are irreversible andare rate limiting. 
? Metabolic pathways include catabolic and anabolic pathways. 
? Occurrence of any pathway is specific within a cell, tissue, or organ. 
Metabolism is the sum total of the entire set of biochemical processes and all the chemical 
reactions occurring inside a cell or an organism for sustenance of life. The chemical 
reactions start with a primary compound, which acts as substrate or reactant. After the 
completion of reaction the compound formed is known as product. Energy exchange 
(facilitated mostly by ATP) occurs during the reaction as well as oxidation-reduction mayalso 
occur during the metabolic reactions. All the biological reactions are catalyzed by enzymes, 
which are proteinaceous in nature. The aspects, which govern metabolic reactions, are 
discussed further in the following sections. 
Thousands of biochemical reaction occurring inside cell can be divided into basic types 
namely:  
Oxidation-reduction- Transfer of electron/s 
Hydrolysis- Bond cleavage with addition of H2O 
Ligation- Covalent bond formation (requires ATP) 
Isomerization- Isomer formation by rearrangement of atoms 
Group transfer- Involves transfer of some group e.g. phosphorylation