Introduction to Biochemistry | Definition, History, Scope, and Fields of Biochemistry

    Explore the fascinating world of biochemistry with our in-depth blog post on the definition, history, scope, and fields/branches of biochemistry. Whether you're a medical/healthcare professional, such as an MBBS, BS Nursing, Paramedic, Nutritionist, or Food Chemist, or simply a general reader or researcher, this blog post is designed to help you understand the subject matter and its relevance in today's world. From the origins of biochemistry and its evolution over time to the various branches and fields it encompasses, this blog post will give you a comprehensive understanding of biochemistry and its importance in the healthcare industry.    

Introduction to Biochemisty for Medical/Health Knowledge lovers, students and researchers
From Health, Education, and Skills

What is Biochemistry?

Definition of Biochemistry

The branch of science (Biology + Chemistry) that deals with the study of the Synthesis of biological compounds, decomposition of biological molecules, as well as reactions that take place within the biological systems, is called biochemistry.

In simplest words, we can say that Biochemistry is the chemistry of life i.e, the chemistry of plants, animals, and microorganisms. Biochemistry takes the advantage of both, Biology and Chemistry, to study and understand the chemical structures, functions, and composition of biomolecules, such as Carbohydrates, Proteins, Vitamins, Lipids, and Nucleic Acids (DNA and RNA).    

Biochemists also find out how biochemicals affect and play role in life processes like respiration, digestion, reproduction, heredity, growth, metabolism, and many more. They also search out for biochemical causes of disease and in turn develop chemotherapeutic drugs for preventing such diseases to develop. In this way, biochemists provide important data to pathologists. Thus we can say that biochemistry act as the backbone of medical sciences.  

History of Biochemistry

Although Biochemistry emerged in the early 19th century, it is believed that before its appearance as a scientific discipline, Greeks showed interest in the chemical and biological composition of life. The history of Biochemistry involves searching for complex biomolecules and their metabolic pathways within the living system, as given below

• In 1833 Anselme Payen discovered the first-ever enzyme, diastase (today known as amylase).
• In 1842 Justus von Liebig presented a chemical theory of metabolism.
• In 1848, the word Biochemistry was first recorded in English.
• In the 1860s Louis Pasteur (a bacteriologist) stated that yeast and bacteria cause fermentation.
• In 1869 nucleic acid (later proved to be DNA) was isolated from pus cells.
• In 1877 E.Buchner proved that fermentation could also occur in a pressed juice of yeast, that is free from living cells.
• In 1903 Carl Neuberg (along with some credit to Franz Hofmeister) introduced Biochemistry as a new scientific discipline, thus considered the father of Biochemistry. 
• In 1926 it was understood that enzymes are proteins in nature, by studying the first pure crystalline enzyme called urease. 
• In 1929 ATP (Adenosine-tri-Phosphate) was isolated from muscles.
• In 1935 it was found that Vitamin B2 was found to be an integral part of an enzyme, thus it was known that vitamins can prevent some diseases.
• In the same year i.e. in 1935 two U.S Chemists Schoeheimer and Rittenberg used radioactive isotopes to trace the path of elements and compounds in biological systems.
• In 1940 Lipmann showed that ATP is the energy currency of the cell.

Role of Liebig and Louis Pasteur in the History of Biochemistry

In the 19th century, two scientists Leibig and Louis Pasteur successfully applied chemistry to the study of biology. In his classic works in the 1840s, Liebig explained how Photosynthesis is responsible for sustaining life on planet earth. He stated that animals depend on organic compounds that are obtained from plants, thus animals are dependent on plants for their nutritional needs. Furthermore, he also explained that plants depend on animals because animals' excreta and decay are re-utilized by the plants for their successful survival. 

Leibig also gives birth to another applied science in the field of Chemistry i.e. Agricultural Chemistry by pointing out that chemical analysis of plants is essential for knowing plants' nutritional requirements that should be provided in fertilizers.

Some of the main Branches of BioChemistry | Scope and Fields of Biochemistry 

The wide scope of Biochemistry can be divided into specialized fields, so that can be studied with ease, each of these fields is known as the Branch of Biochemistry or Field of Biochemistry.

1. Cellular Biochemistry

The branch of Biochemistry that deals with the study of biochemical processes occurring at the cellular level is called cellular biochemistry.

Cellular Biochemistry is mainly concerned with studying the processes and events that occur in cells due to the addition, removal, synthesis, or decomposition of bio-elements or bio-molecules.

Cell Biologists (known as Cytologists) study all aspects of the cell, the majority of these aspects are chemical in nature. For example, a Cytologist may want to know how small units (monomers) combine to form large units (polymers), or how polymers break down in order to be get converted into monomers within the cell. Similarly, he/she may want to know how insulin lower blood glucose levels by converting it into ATP or how it is stored in the form of Glycogen (a Glucose storage form) in muscles and the liver. In order to answer these questions, he/she will have to study Cellular Biochemistry.    

Examples of Cellular Biochemistry in action

• Glycolysis (breakdown of Glucose into Pyruvic Acid).
• Kreb's Cycle 
• Electron Transport Chain, etc   

2. Molecular Biochemistry

The branch of Biochemistry that deals with the study of structures, functions, composition, and decomposition, as well as reactions involved in or by biological molecules, is called molecular biochemistry.

Molecular biochemists focus on how biological molecules, such as water, carbohydrates, proteins, lipids, and nucleic acids, are involved in making life possible. How do these biomolecules affect on physiological functions of living organisms (Animals, Plants, and Microorganisms)? They also want to know how a patient can be treated if he/she has an abnormality in one or more physiological disturbances that occurs due to these biomolecules.

Molecular Biochemistry can be further categorized into Biochemistry of DNA, Biochemistry of Proteins, Biochemistry of Lipids, Biochemistry of Carbohydrates, Biochemistry of Hormones, etc.

Examples of Molecular Biochemistry in action

• ATP synthesis from mononucleotides.
• Formation of RBCs
• Accumulation of lipids, that then cause heart diseases, etc

3. Animal Biochemistry

The branch of Biochemistry that deals with the study of structure, functions, composition, and decomposition of biochemicals, as well as biochemical processes involved in the body of animals only, is called Animal biochemistry.

Animals form the most complex and diverse group among all living creatures, thus having more complexities at the cellular, molecular, morphological, gene, and physiological levels. In order to know more and more about animals' biochemical life, it is important for Animal Biochemists to have a close look at what's happening at the molecular level during health and illness. 

Examples of Animals' Biochemistry in action       

• Glycogenesis (Formation of Glycogen).
• Glycolysis (Breakdown of Glucose)
• Glyconeogenesis (Formation of Glucose from non-carbohydrate sources).
• Lipogenesis and Lipolysis (Formation and breakdown of Lipids, respectively), etc

4. Plant Biochemistry

The branch of Biochemistry that focuses on biological molecules, and biochemical processes involved in the body of plants only, is called Plant biochemistry.

Plants also require nutrients (in the form of fertilizers), need Optimum pH and temperature for the proper working of enzymes, and have systems (such as a transport system). For all these factors to work at a normal physiological scale, Plant biochemists study Plant biochemistry. For agriculture purposes, Plant biochemists provide valuable data on how plants can be get protected from pesticides, insecticides, herbicides, etc.    

Examples of Plant Biochemistry in action       

• Photosynthesis 
• Photorespiration
• Accumulation of Glucose in the form of starch.
• Plant cell Biochemistry, etc.

5. Immune Biochemistry

The branch of Biochemistry that deals with studying all the chemical aspects of the immune system is called Immune Biochemistry.

The immune system is responsible for defending our body against pathogenic attacks. For this killing attempt, our immune system uses different types of proteins such as Interferon, antibodies, etc. These, and other proteins, pass through a series of biochemical reactions taking place in different types of immune cells, such as T-Cells, B-Cells, etc so that any foreign substance can be killed. Immune biochemists find out how these complex proteins are formed, how they get transported at the site of infection, and then how they kill microbes? Immune biochemistry plays a crucial role in pathology and other medical science disciplines.

6. Endocrinology  

Endocrinology deals with the study of chemical, anatomical, physiological, and pathological aspects of the endocrine system i.e Glands and their respective hormones.

Dealing with chemical aspects, such as the chemical nature of hormones, biochemical/artificial synthesis, chemical reactions, and abnormalities due to chemical imbalances in the hormonal systems are some of the major disciplines that facilitate pathologists and pharmacologists in finding and treating endocrine diseases. 

Examples of Endocrinology in action       

• Insulin biosynthesis.  
• Synthesis and Secretion of erythropoietin (a hormone that facilitates RBC production), etc. 

7. Enzymology

Enzymology deals with the study of the structure, functions, synthesis, classification, actions, and reactions of enzymes.     

Enzymes act as biological catalysts and are involved in all types of biochemical reactions, such as catabolic reactions (reactions involved in the breakdown of biochemicals), anabolic reactions (reactions involved in the synthesis of biochemicals), and amphibolic reactions (which are both catabolic and anabolic).

Examples of Enzymology in action       

• Fat digestion in our gut by the action of Lipases.  
• Salivary amylase (present in saliva) helps in the conversion of starches into sugars.

8. Metabolic Biochemistry  

This branch, as a field of biochemistry, deals with the study of biochemicals, and their transformation, involved in metabolic pathways.     

Metabolism is the sum of all reactions taking place in the body of living organisms. Some metabolic reactions involve the breakdown of biomolecules (called Catabolic reactions), while others cause the synthesis of biomolecules (called Anabolic reactions). These reactions pass through a series of steps, known as metabolic pathways, in order to get converted into a final product.

Metabolic biochemists concentrate on the structures, functions, changes, and composition of organic and inorganic biochemicals that take part in the metabolic pathways.

Examples of Metabolic Biochemistry in action 

• Conversion of Glucose into Pyruvic Acid in order to generate ATP through a metabolic pathway known as Glycolysis.
• Erythropoiesis, the process of formation of RBCs in bone-forming cells, etc. 

9. Xenobiotics (Greek Word: "Xenos" means "Stranger")

Xenobiotics is the study of biochemical synthesis or decomposition of those chemical substances that are neither present nor expected to be present normally, in organisms.        

Xenobiotics include a wide range of chemical substances that are not part of our body i.e. act as foreign chemicals to the body. Xenobiotics may be pollutants, additives, drugs, pesticides, cosmetics, petrochemicals, snake venom, etc or they may also be the metabolites of other organisms. Thus, Xenobiotics may be exogenous as well as endogenous in their origin.

Studying xenobiotics, as one of the disciplines of Biochemistry, helps us to know how they cause humans (or plants) metabolic and physiological abnormalities, but also helps Pharmacologists to develop chemotherapeutic drugs for treating diseases caused by them.

Examples of Xenobiotics in action    

• Drugs toxicity
• Effect of neurotoxins released in snake venom.   

10. Biochemical Genetics  

This branch deals with all the chemical aspects related to the study of the structures, and functions, as well as any abnormalities of genes.

Gene (present in the DNA of the chromosome) is the basic structural and functional unit of heredity and heredity play a major role in the transmission of characteristics from parent to offsprings. These characteristics are encoded in genes, which are decoded by RNA in order to form specific proteins according to genetic code. These proteins in turn form our every characteristic. These processes, and others like these, occur through a series of chemical events taking place at the cellular level. As Biochemical geneticists, we have to find out all the biochemicals and their processes involve in genetics.

Examples of Biochemical Genetics in action

• Enzymes and their effect on DNA replication.
• Chemical events that take place in genetic code translation.
• Understanding and preventing genetic diseases that are biochemical in nature.