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This book entitled “Veterinary Biochemistry and Biotechnology” is Multiple Choice Questions in Biochemistry and Biotechnology and it has been written to introduce a comprehensive question bank to students and academicians covering nearly the entire syllabus in Biochemistry as well as Biotechnology. MCQ book is a backbone for all entrance/competitive examinations throughout the globe with a best approach for the constitution of an important method for objective assessment of an examinee’s knowledge. Every chapter has been written and reviewed by experienced fallible teacher of relevant subject matter with a good attempt to provide best answer at the bottom of the questions. The book is formed in concise, up-to-date, accurate and reliable fashion for the readership. The book covers thirty one chapters covering almost all of the biochemistry and biotechnology syllabus with a validation from the reference biochemistry and biotechnology books. The book is especially mainly structured for the undergraduate, postgraduate, MBBS medical biochemistry students, academicians and researcher and other allied courses. The book is very useful for the students preparing University exam, PG entrance exam, NET examinations, State PSC, to make it as simplest ones to real brain teasers. The book is planned on the basis of the current pattern of exam, and will be benefitted for the students preparing any competitive examination confidently and successfully. The book is organized in a simple lucid language so that the students can easily understand the same and also choose the correct option from those. Henceforth, when errors or serious omissions are detected and examined, or if any clarity of presentation of the chapter should be improved, constructive feedback would also be genuinely appreciated.

Introduction “Bio” means pertaining to life and “Chemistry” is the Study of chemicals and chemical reactions. So Biochemistry may be defined as the study of chemical processes within and relating to, living organisms. It is a field of science that explores the chemical processes and substances within living beings. Biochemistry bridges the gap between biology and chemistry, aiming to understand how biological molecules give rise to the complex processes of life. In other words “Biochemistry is the science dealing with various molecules that are present in living cells and organisms and their chemical reactions.” Scope of Biochemistry As a life itself, the scope of biochemistry is vast and ever changing. It has its influence on vide range of fields playing a major role in understanding and influencing living organisms. Here some of the fields were put forth that have applications of biochemistry. Human and Medical Healthcare Nutrition and metabolism: As they say, we are what we eat; nutrition is a prime aspect of the being and knowing how the body process what it eats is a necessary knowledge that comes from biochemical aspect of nutrition. The dietary component of the beings converting into energy, protein and other essential bodily macro and micro molecules is a great knowledge imparted by biochemistry aspect of nutrition. Metabolism which broadly includes anabolism and catabolism deals with various activities of the physiological systems with in the body. Knowledge of biochemistry is very essential these days as the metabolic diseases are very much prevailing. Biochemistry imparts basic to complex know-hows about various metabolic processes and their derailments.

Introduction pH is a quantitative measure of the concentration of hydrogen ions in a solution. The pH scale ranges from 0 to 14, with 7 being neutral. Lower pH indicates acidity, while higher pH indicated alkalinity. Pure water at 25°C has a pH of 7.0 as the concentrations of H3 O+ and OH-. pH is defined as potential of hydrogen and is a measure of how acidic or basic a substance or solution is. The concentration of Hydrogen (H+) in a solution determines its pH. Higher concentrations of H+ ions correspond to lower pH values (more acidic), and lower concentrations of H+ ions correspond to higher pH values (More alkaline/basic). pH is an important measurement concept in many fields, including chemistry, biology, and environmental science. pH of blood and other fluids of the body, secretions etc?, determine the health status of an individual. Likewise, pH determines the quality of soil for plant growth. In medical sciences, pH plays a crucial role in maintaining a healthy internal environment for various bodily functions. Internal environment of an animal or human is tightly regulated more so the pH of different body fluids like blood, saliva and stomach acid. pH balance is a very prime aspect to maintain homeostasis inside a biological system. Speaking of which the first thing that comes to mind is the enzyme function. Many enzymes have a specific pH range for optimal activity. Any deviation from this specific pH range not only significantly disrupt their function but also hinder biochemical processes involved. Most vital operations of a cell are nutrition transport and waste disposal i?e?, excretion. pH of the fluids surrounding cells impacts these activities; hence, maintaining a proper pH is vital for healthy cell function. Different organs of the body need to maintain different pH ranges for functioning accordingly. Stomach operates at acidic pH to digest the food material ingested whereas, blood need alkaline pH for optimal oxygen transport by RBC.

Introduction The smallest, most basic, most primitive organisms are known as prokaryotic (Greek: pro= primitive or prior, and karyon = nucleus). Likely, they originated around 3.5 billion years ago. Bacteria, such as Mycoplasma and Cyanobacteria, are known to contain these cells. A prokaryotic cell is a deeply organized single-enveloped system. Its constituent nuclear parts are encased in a plasma membrane, with the cytoplasmic ground substance encircling the center. Prokaryotic cells’ cytoplasm lacks distinct cytoplasmic organelles, the nuclear envelope, and any other cytoplasmic membrane. Despite being incredibly thin and delicate structures, in Eukaryotes plasma membranes are essential to many of a cell’s most vital processes. Membranes are lipid-protein assemblages where non-covalent linkages hold the constituents in place in a thin sheet. Both integral protein and phospholipid lateral mobility are significantly impacted by the physical condition of the lipid bilayer. The plasma membrane is a selectively permeable barrier that permits solute passage via assisted diffusion, active transport, and simple diffusion via membrane channels or the lipid bilayer. A system of membrane organelles, such as the endoplasmic reticulum, Golgi complex, and lysosomes, is found in the cytoplasm of eukaryotic cells. These organelles are physically and functionally connected to the plasma membrane and one another. The cytoplasm is separated into a luminal region inside the ER membranes and a cytosolic space outside the membranes by the endoplasmic reticulum (ER), a network of tubules, cisternae, and vesicles. Additionally, the ER is where the majority of a cell’s membrane lipids are generated and transported to different locations. Proteins’ asparagine residues are added with sugars (a process known as glycosylation), which starts in the rough ER and continues in the Golgi complex.

Introduction Carbohydrates are essential organic biomolecules/macromolecules composed of carbon c., hydrogen (H), and oxygen (O) atoms, typically in a 1:2:1 ratio. They are one of the four major classes of biomolecules, alongside proteins, lipids, and nucleic acids. Carbohydrates play critical roles in energy storage, structural integrity and cell signaling. Carbohydrates with an aldehyde as their functional group are called Aldoses. Those with keto as a functional group are called Ketoses. Classification of Carbohydrates: They are broadly classified into three major groups: 1. Monosaccharides: The simplest form of carbohydrates, consisting of a single sugar unit. They cannot be hydrolyzed to yield simpler forms of sugar. They can be subdivided into trioses, tetroses, pentoses, hexoses, heptoses and octoses etc., depending upon the number of carbon atoms they possess. Important monosaccharides are: • Glycerose / Glyceraldehyde (Aldotriose): Glyceraldehyde 6-phosphate is an intermediate in Glycolysis. • Ribose (Aldopentose): found in Nucleic acids. • Glucose (Aldohexose): The primary energy source for cells, known as blood sugar. • Fructose (Ketohexose): Found in fruits (fruit sugar), a major component of sucrose. • Galactose (Aldohexose): Known as brain sugar. It is a part of lactose sugar.

Introduction Lipids may be regarded as organic substances relatively insoluble in water, soluble in organic solvents (chloroform, ether, benzene, ethanol and other non-polar solvents, etc.), actually or potentially related to fatty acids and utilized by living cells. Lipids are a diverse group of hydrophobic or amphipathic biomolecules that play crucial roles in energy storage, cell membrane structure, and signaling. Unlike carbohydrates and proteins, lipids are not defined by a specific polymer structure but rather by their solubility in non-polar solvents. Broadly lipids are classified based on their function as ‘Storage lipids’ and ‘Structural lipids’. Some of them are co-factors, hormones, electron carriers, light-absorbing pigments and hydrophobic anchors of proteins. Fatty Acids: Fatty acids are straight aliphatic chains with a methyl group at one end and a carboxyl group (-COOH) at the other end. They are the simplest form of lipids. • Saturated Fatty Acids have no double bonds between carbon atoms, leading to straight chains (e.g., palmitic acid). • Unsaturated Fatty Acids contain one or more double bonds, causing kinks in the chain (e.g., oleic acid). Fatty acids containing more than one double bond (polyunsaturated fatty acids/PUFA) are found in relatively minor amounts.

Introduction Proteins are complex biomolecules composed of amino acids, playing crucial roles in virtually all biological processes. They serve as enzymes, hormones, structural components, signaling molecules etc. Structure/ Levels of Organization of Proteins Generally, Proteins are polymers of L-alpha amino acids, linked by peptide bonds. The sequence and structure of these amino acids determine the protein’s function. Protein structure is hierarchically organized into four levels: 1. Primary Structure • The linear sequence of amino acids in a polypeptide chain, determined by the genetic code. 2. Secondary Structure • Local folding of the polypeptide chain into structures such as α-helices and β-pleated sheets, stabilized by hydrogen bonds.

Introduction A pentose sugar, one or more phosphate groups, and a nitrogenous base (purine or pyrimidine) make up a nucleotide. Phosphodiester bonds, which connect the 5’-hydroxyl group of one pentose to the 3’-hydroxyl group of the next, bind nucleic acids together as polymers of nucleotides. RNA and DNA are the two different forms of nucleic acids. RNA nucleotides contain ribose, while uracil and cytosine are typical pyrimidine bases. Thymine and cytosine are common pyrimidine bases, and DNA contains 2’-deoxyribose in its nucleotides. In both RNA and DNA, adenine and guanine are the main purines. There is ample evidence to suggest that genetic information is encoded in DNA The Avery MacLeod-McCarty experiment, in particular, demonstrated how DNA obtained from one bacterial strain may infiltrate and change the cells of another strain, giving it some of the genes from the donor. The Hershey-Chase experiment demonstrated that a bacterial virus’s DNA contains the genetic instructions needed for the virus to replicate in a host cell, but not its protein coat. Watson and Crick proposed that native DNA is made up of two antiparallel chains arranged in a right-handed double helical configuration based on a compilation of numerous published data points. A-T and G-C, two complementary base pairs, are created by hydrogen bonds inside the helix. 10.5 base pairs are stacked per turn, perpendicular to the double helix’s long axis, at a distance of 3.4 Å. There are various structural configurations for DNA A- and Z-DNA are two variants of the Watson-Crick form or B-DNA The DNA molecule bends as a result of certain sequence-dependent structural differences.

Introduction All enzymes are proteins, except a tiny subset of catalytic RNA molecules. Most of the classical metabolic enzymes are named by adding the suffix -ase to the name of their substrates or to a descriptive term for the reactions they catalyze. For example, urease has urea as a substrate. Alcohol dehydrogenase catalyzes the removal of hydrogen from alcohols (i.e., the oxidation of alcohols). A committee of the International Union of Biochemistry and Molecular Biology (IUBMB maintains a classification scheme that categorizes enzymes according to the general class of organic chemical reaction that is catalyzed The six classes are Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases, and Ligases. The integrity of their natural protein structure is necessary for their catalytic activity. Catalytic activity is typically lost when an enzyme denatures or dissociates into its constituent subunits. An enzyme’s catalytic activity is always eliminated when it is disassembled into its constituent amino acids. Thus, the catalytic activity of protein enzymes depends on their primary, secondary, tertiary, and quaternary structures. Aside from their amino acid residues, certain enzymes don’t need any other chemical groups to function. Others need a cofactor, which is an extra chemical element. Cofactors can be complex organic or metalloorganic molecules called coenzymes, or they can be one or more inorganic ions like Fe2+, Mg2+, Mn2+, or Zn2+.

Introduction Energy is the major source required to maintain the structure and function of all living cells. This energy is derived from oxidation of carbohydrates, lipids and proteins that is taken in the form of diet. The energy liberated from the process of oxidation is generally captured in the form of ATP, which is known as energy currency of the living cells. Each gram of carbohydrate and protein gives about 4 Kcal on oxidation, while each gram of fat gives about 9 Kcal. Oxidation means addition of oxygen or removal of hydrogen from a compound or removal of electron from an ion or atom increasing its positive charge. Reduction means removal of oxygen or addition of hydrogen to a compound or addition of electron to an ion or atom decreasing its positive charge. Commonly the oxidation reactions are conjugated with reduction reactions and known as redox reactions. Redox reactions are often associated with release of energy. The redox chain constitutes chain of different compounds of increasing redox potentials between hydrogen and oxygen. The living cells depend on redox reactions for their energy requirements. The reactions start by removal of H2 from the substrate, which is then transferred to different components of redox chain, then finally to oxygen to form water. Components of redox chains have a redox potential higher than hydrogen and lower than oxygen.

Introduction Carbohydrates, the aldehyde/ ketone derivatives of the higher polyhydric alcohols, or compounds that yield these derivatives on hydrolysis, constitute of mainly four groups viz. monosaccharides, disaccharides, oligosaccharides and polysaccharides. Energy comes mostly from carbohydrates, and products of their degradation are also used for the synthesis of other substances including fatty acids, cholesterol, amino acids etc They are also components of compound lipids, conjugated proteins, and some of their derivatives can even function as medications (e.g., cardiac glycosides, etc). Disorders such as glycogen storage disorders (GSDs) and galactosemia can be brought on by an inherited lack of certain enzymes in the metabolic pathways of various carbohydrates. Diabetes mellitus is characterized by disruption of the metabolism of glucose. In ruminants, the end products of digestion are largely volatile fatty acids viz. acetic acid, propionic acid and butyric acid and some monosaccharides. As they pass through the ruminal epithelium, they undergo different degrees of metabolism. The fate of volatile fatty acids are as follows: Acetate as precursor to Acetyl CoA (TCA cycle; fat synthesis); Propionate as precursor to glucose (glycolysis; milk lactose) and Butyrate as precursor to Acetyl CoA (TCA cycle). All the digested and absorbed monosaccharides and volatile fatty acids enter into the liver, where two mechanisms operate such as withdrawal of carbohydrates from blood (e.g. glycogenesis; glycolysis etc) and release of glucose by liver to blood (e.g. glycogenolysis; gluconeogenesis etc). In case of monogastrics, the processes of digestion/ fermentation of carbohydrates especially occur in the small intestine. The fate of absorbed glucose and metabolic conversions in the animal body mainly comprise of storage as glycogen in liver and muscle (small amount); oxidation of glucose for providing energy (via Glycolysis pathway; other alternative pathways such as Hexose Monophosphate Pathway (HMP)/ HMP Shunt and Uronic acid pathway etc) and fat synthesis as well as storage in the form of fat in adipose tissue.

Introduction Protein metabolism is a complex and multifaceted process that plays a crucial role in the overall health and function of living organisms. At the most fundamental level, protein metabolism involves the synthesis, breakdown, and utilization of proteins, which are essential macromolecules that serve a wide range of structural, functional, and regulatory roles within the body. The process of protein synthesis, or translation, begins with the transcription of genetic information stored in DNA into messenger RNA (mRNA) molecules. These mRNA molecules then serve as templates for the assembly of specific sequences of amino acids into polypeptide chains, which ultimately fold into the three-dimensional structures of functional proteins. This highly regulated process is essential for the production of the diverse array of proteins required for cellular processes, tissue repair, immune function, and numerous other physiological activities. In contrast, protein degradation, or catabolism, refers to the breakdown of proteins into their constituent amino acids. This process is mediated by various proteolytic enzymes, such as endopeptidases, exopeptidases, and dipeptidases, which cleave the peptide bonds that hold the amino acid residues together Protein degradation serves important functions, such as the recycling of amino acids for energy production or the synthesis of new proteins, the removal of damaged or misfolded proteins, and the regulation of cellular signaling pathways.

Introduction Lipids (dietary or body reserve) serves as the major source of energy for the body at the time of carbohydrate depletion. Triacyl glycerol (TG) forms the major part of lipids alongwith phospholipids, cholesterol and fat-soluble vitamins. The different forms of lipids are utilised by the body for generation of energy in the form of ATP. In addition, it serves as the source of essential fattyacids and vitamins for different metabolic purpose. Dietary triacylglycerols (TG) are digested by lipase group of enzymes (lingual, gastric, pancreatic and intestinal) secreted by the digestive tract into free fatty acids and 2-monoacylglycerols. The 2-monoacylglycerols are either absorbed as such or hydrolysed into glycerol and fatty acids which are then absorbed independently. The glycerol and fatty acids are distributed to different tissues through circulation and utilised in the following ways i. Storage in fat cells of adipose tissue in the form of triacylglycerols. ii. Oxidised in peripheral tissues for production of energy. iii. converted to glucose in hepatic cells in the process of gluconeogenesis. iv. Synthesis of other derived compounds like steroids and eicosanoids in gonadal and other tissues v. Synthesis of phospholipids and cholesteryl esters.

Introduction Vitamins are the organic derived accessory food factors apart from carbohydrate, lipid and proteins meant for specific biological functions, optimum growth and health of an organism. These factors are are required in minute amount in the diet for proper functioning of biological enzymes. The term accessory factors were given by Hopkins to the essential nutrients present in the natural foods. Funk (1913) coined the term vitamine to the active principal present in rice polishings. Vitamins are classified into two categories like fat soluble A and water-soluble b Vitamins A, D, E, K are fat soluble whereas Vitamins B and C are water soluble. The B group of vitamins include vitamin B1, B2, B6, biotin folic acid, B12 etcall the fat-soluble vitamins are isoprenoid in nature consisting of repeating isoprenoid units. And meant for diversified functions. The water-soluble vitamins are heterogenous group of compounds generally not stored in the body and readily excreted in urine. These are mostly act as coenzymes for the vital biological enzymes deficiency of which reflects in the form of various deceases. Vitamin A, include retinoid group of compounds like retinol, retinal and retinoic acid Retinol is a primary alcohol containing β-ionone ring with isoprenoid units, double bonds and hydroxyl group. Naturally it exists as ester of long chain fatty acids. Retinal is the aldehyde form whereas Retinoic acid is the acid form. Carotene is provitamin A normally found in plant origin foods that in the intestine gives rise to two moles of retinal by enzyme carotene 15-15-dioxygenase. Diet contains retinol esters and p-carotene. Retinol esters are hydrolyzed into fatty acids and retinol that absorbed into intestinal mucosal cells. p-carotene Is absorbed and converted into retinal by p-carotene dioxygenase. Retinal then converted into retinol. In the intestinal mucosal cells, retinol re-esterifies with fatty acid to form retinol ester.

Introduction According to the body needs, minerals may be divided into 2 groups like macrominerals and microminerals. Macrominerals are required in amounts greater than 100 mg/day. They include 6 elements like calcium, phosphorus, magnesium, sodium, potassium and chloride. Whereas microminerals are also known as trace elements and are required in amounts less than 100 mg/day. They include 10 elements like chromium, cobalt, copper, fluoride, iodine, iron, manganese, molybdenum, selenium, zinc and silicon. Some minerals are always required since small amounts of inorganic salts are always excreted Fruits, vegetables and cereals are the chief sources of the mineral elements in the diet. Milk products supply the majority of the calcium and phosphorus in the diet. Milk and milk products are the richest source of calcium along with beans, leafy vegetables and egg yolk. It is absorbed from upper small intestine. Absorption of calcium is active process and requires calcium binding protein present in the intestinal mucosal cells. The absorption is regulated by vitamin D, parathyroid hormone, high protein diet, pH, high dietary lactate and citrate are the factors that promotes calcium absorption. Whereas high dietary phosphate, alkalinity and impaired fat absorption are the factors that inhibits calcium absorption. Of the total body calcium, 99 % present in bones and teeth in the form of hydroxyapatite and 1 % is present in body fluids and other tissues. Calcium in bones acts as a reservoir, which helps to stabilize calcium ions in plasma and extracellular f luid Parathyroid hormone and active vitamin D stimulate osteoblasts while estrogen hormone inhibits osteoclasts.

Introduction Energy metabolism is the complex process by which living organisms convert nutrients into energy for survival, growth, and reproduction. It involves a series of interconnected biochemical reactions that occur within cells. Key Components of Energy Metabolism • Catabolism: The breakdown of complex molecules (carbohydrates, proteins, and fats) into simpler ones, releasing energy. • Anabolism: The synthesis of complex molecules from simpler ones, requiring energy input. • ATP: The primary energy currency of cells, used to power various cellular processes. • Enzymes: Catalysts that facilitate metabolic reactions.

Introduction Biochemistry of blood is extremely complex. It plays vital role in maintaining homeostasis with in the body. Blood is a specialized connective tissue which is a fluid that circulates all through the body in cardio vascular system. Blood consists of 55 per cent of plasma and 45 per cent of cellular components. Plasma: A straw coloured liquid component of blood. Understanding the chemical basis of plasma is very crucial for diagnosis and treating various conditions. The compositional breakdown of plasma can be put forth as 90-92 % of water that acts as transport medium for the remaining 8-10 % of the solutes. Solutes further can be classified as electrolytes (salts), proteins, Lipids, other nutrients and waste products. Plasma electrolytes: These are the minerals found in the blood that are electrically charged. Their role is very crucial in lot of physiological activities like • Maintaining the balance of fluids interior and exterior to the cells. • Carries electrical signals all through the body • Helps in contraction of muscles • Regulates blood pressure

Introduction Human and animal body comprises of various tissues that are the functional unit of organ functioning and coordination. The tissues are further consisting of well differentiated cells that makes the tissue to behave in a special way for a particular purpose. The animal tissues are divided into epithelial, connective, muscular and nervous tissues. Epithelial tissues form the protective covering and inner lining of the body and organs. Connective tissues develop from the mesodermal cells of the embryo. they support and bind other tissues in the body. The muscular tissue develops from the mesoderm of the embryo and meant for movement and locomotion. Nervous tissue makes up the peripheral and the central nervous system and is responsible for initiation and transmission the nerve impulse. The tissues are biochemically composed of water, lipid, protein, ash, and carbohydrate along with other mineral and vitamins that are needed for its basic functioning. The extracellular matrix (ECM) forms a major component of connective tissue that forms layer and surrounds the cells or tissues meant for protection, signalling and communication. The protein component of ECM basically includes collagen, elastin, keratins, fibrillin, fibronectin, laminin and proteoglycans. Collagen is the major protein component of connective tissue that provides tensile strength, shape and fixes the organ in its position. Collagen is not homogenous rather consists of around 19 different types of proteins. There are around 30 variants of protein found in collagen. collagens type I and type II are respectively found in skin and bone. Collagen is triple helical polymer of highly elongated fibrils consisting of around 1000 amino acids majority of which consists of glycine along with proline and hydroxyproline. The forces like hydrogen bonds, covalent bonds, electrostatic, hydrophobic, and van der Waals are responsible for stabilizing the structure of collagen.

Introduction Robert Brown discovered the nucleus in some plant cells in 1831. After analyzing tissues from a range of animals and plants, T. Schwann (1839) declared, “All living organisms are composed of cells.” The fundamental elements of Prokaryotic and Eukaryotic cells The simplest cells, called prokaryotic cells, have a straightforward structural arrangement. There is only one membrane system in it. They contain rickettsia, spirochete, mycoplasma, virus, blue-green algae, and bacteriablue-green algae, or cyanobacteria are the largest and most intricate prokaryotes, where higher plant photosynthesis occurs and have changed throughout time. Prokaryotic cells Prokaryotic cells range in size from 1 to 10 µm. They take place in a range of formats. A bacterial cell is made up of three basic parts: I. External layer: It is composed of the inner cell or plasma membrane, middle cell wall and outer slimy capsule. a. Cell membrane: The thin, flexible membrane of the cell, composed of proteins and lipids, regulates the flow of chemicals throughout the cell. It carries respiratory enzymes for reactions that release energy. Respiratory enzymes are found in mesosomes, which are folded regions of the plasma membrane that are compared to the mitochondria in eukaryotic cells. Similarly, the pigments and enzyme molecules found in photosynthetic cells are linked to the in-folds of the plasma membrane known as photosynthetic lamella, which is responsible for absorbing light and converting it into chemical energy. b. The cell wall: It is the non-living, semi-rigid layer that encloses the cell membrane, with a thickness that varies from 1.5 to 100 µm. It is chemically made up of peptidoglycans. Certain bacteria, such as mycoplasma, don’t have cell walls.

Introduction Nucleic acids, primarily DNA and RNA, are essential for the storage and expression of genetic information. Under physiological conditions, the amino and oxo tautomers of purines and pyrimidines predominate. Adenine a., guanine (G), cytosine c., thymine (T), and uracil (U) are the main building blocks of nucleic acids. Other building blocks include 5-methylcytosine, 5-hydroxymethylcytosine, pseudouridine, and N-methylated heterocycles. A -glycosidic bond connects D-ribose or 2-deoxy-D-ribose to the N-1 of a pyrimidine or the N-9 of a purine, with the syn conformers being the most common. Nucleotides are the monomeric units of nucleic acids that contain a phosphate group attached to the sugar’s 3’ or 5’ hydroxyl. Extra phosphate groups form nucleoside diphosphates and triphosphates. These have high group transfer potential and help make covalent bonds. Cyclic phosphodiesters cAMP and cGMP act as second messengers. 3′ 5′ phosphodiester bonds link nucleotides to form polynucleotides, which have a directional 5′ and 3′ end. Four bases—A, G, C, and T—compose DNA, and hydrogen bonds (A to T, G to C) hold them together to form a double helix. Human DNA consists of approximately 3 billion base pairs organized into 23 chromosomes, encoding around 25,000 protein-coding genes and various non-coding RNAs (ncRNAs).

Introduction In a historic landmark, Genentech, a young Californian Company pioneering in gene splicing (which includes recDNA technology, genetic engineering, gene transplantation, gene cloning), saw its stock price skyrocket form $35 to a staggering $89 within just 20 minutes of the New York Stock Exchange’s opening bell on October 15, 1980. This was marked as the fastest stock price growth ever witnessed on that exchange. The company’s success was attributed to the ground-breaking work it had been involved in producing human insulin through genetic engineering that offered a revolutionary alternative for diabetics allergic to the then traditional insulin of porcine origin. Genentech’s pioneering work in gene splicing has its roots in the early 1970s. In 1972, Stanley Cohen and Herbert Boyer were credited with creating the first recombinant DNA molecule. Their experiments demonstrated the ability to create recombinant DNA molecules that could be introduced into bacteria like E? coli, offering a foundation for future advancements in genetic engineering.

Introduction Biochemical techniques are fundamental tools that allow scientists to investigate the molecular intricacies of biological systems, including DNA, RNA, and proteins. These techniques are essential for understanding cellular processes, genetic functions, and disease mechanisms. By employing biochemical methods, researchers can dissect complex biological systems at the molecular, cellular, and genomic levels, paving the way for advances in basic biology and therapeutic interventions.

Introduction Cell culture is a technique that involves the isolation and in vitro maintenance of cells isolated from tissues or whole organs derived from animals, microbes or plants. This technique has immeasurable role in the field of biology. The scientific progress in biology, microbiology and biotechnology in recent years can be credited on the development of cell culture technology. With the development of cell culture the isolation of viruses has become less cumbersome, the assessment of the efficacy and toxicity of new drugs has been easier, new vaccines are being developed and there has been development in biotechnology assisted reproductive technology. In general, animal cells have more complex nutritional requirements and usually need more stringent conditions for growth and maintenance. For the growth of the cell in vitro specific mediums are required by the cells. Previously natural mediums like plasma ,serums were used but with the advent of synthetic media the specific needs of different cell types can be catered with. Cell culture is governed by a provided set of protocols requiring a sterile pure culture of cells, various nutrients for its growth, sterile cell culture hood, appropriate aseptic techniques and the utilisation of suitable conditions for optimal viable growth of cells.

Biotechnology is being harnessed in various aspects of the livestock industry to hasten breed development for improved animal health and welfare, enhanced reproduction, and improved nutritional quality and safety of animal-derived foods. Various biotechnology methods are used in improving the breeding stock of animals. These include artificial insemination (AI), embryo transfer (ET), in-vitro fertilization (IVF), sexing of semen and embryos, micromanipulation of oocytes/ embryos, transgenesis, somatic cell nuclear transfer and the emerging technology on genomics and marker-assisted selection (MAS). Artificial Insemination: One of the earliest perfected technology is artificial insemination (AI) where new breeds of animals are produced through the introduction of the male sperm from one superior male to the female reproductive tract without mating. AI reduces transmission of venereal disease, lessens the need of farms to maintain breeding males, facilitates more accurate recording of pedigrees, and minimizes the cost of introducing improved genetics. Various technologies have evolved that led to the efficient use of AI in developing desired livestock, including the methods of freezing semen or cryopreservation and sperm sexing.

Introduction Water is the most abundant compound in the body, and most of life’s essential processes take place in this aqueous environment. Although there is substantial variation, the total body water (TBW) of most domestic animals is approximately 60% of body weight (0.60 l/kg).Electrolytes are substances that exist as positive or negative charged particles in aqueous solution. The positively charged particles are “cations,” and the negatively charged particles are “anions”. The osmotic properties of a solute in solution are related to the number of particles in solution and not to its weight or its charge. One osmole of a non-dissociable substance is equal to its molecular weight in grams. One osmole of any substance that dissociates in solution into two or more particles is equal to the molecular weight in grams divided by the number of particles into which each molecule dissociates. Osmolarity is defined as the number of osmoles per l of final solution, whereas osmolality is the number of osmoles per kilogram of water. Although the expressions are similar, osmolality more correctly describes the osmotic properties as measured in the clinical laboratory.

Introduction Most glands of the body deliver their secretions by means of ducts. These are called exocrine glands. There are few glands that produce chemical substance that they directly secrete into the blood stream for transmission to various target tissues. These are ductless or endocrine glands. The secretions of endocrine glands are called as hormones. Therefore, it is a chemical substance which is produced in one part of the body, enters the circulation and is carried to distant target organs and tissues to modify their structures and functions. Hormones are stimulating substances and act as body catalysts. The hormones catalyze and control diverse metabolic processes. Despite their varying actions and different specificity’s depending on the target organ, the hormones have several characteristics in common with enzymes. They act as body catalysts resembling enzymes in some aspect. They are required only in small quantities. They are not used up during the reaction. They differ from enzymes because they are produced in an organ other than that in which they ultimately perform their action. The major hormone secreting glands are as follows— Pituitary, Thyroid, Parathyroid, Adrenal, Pancreas, Ovaries and Testes. The hormones are classified into following main classes according to the chemical structures:

Introduction Diagnostic biochemistry, is a branch of laboratory medicine that focuses on the analysis of bodily fluids to diagnose and monitor diseases. This field plays a crucial role in understanding the biochemical mechanisms underlying various conditions, enabling accurate diagnosis, prognosis, and management. The biological samples for diagnosis include blood, urine, cerebrospinal fluid, pleural fluid and tissues. Factors Affecting Serum Enzyme Activity or Protein Level 1. Organ Mass and Enzyme Tissue Concentration: • Higher enzyme concentrations in organs can lead to greater increases in serum enzyme activity during disease. For instance, the liver’s large mass contributes to potential increases in serum ALT activity. 2. Cell Location • The proximity of cellular enzymes to the blood, urine, or other fluids determines the fluid in which an enzyme’s activity will increase upon cell injury. For example, renal tubular gamma-glutamyltransferase (GGT) is released into urine, not blood, following injury.

Introduction Immunology deals with the body defence system consisting of various cells and biomolecules that prevents entry of foreign infectious and toxic agents by different mechanisms. The mammalian immune system operates in two ways like innate or non specific immunity and adaptive or acquired or specific immunity. Innate part constitutes the physical (skin, hair, tears and mucous secretions) containing enzymes that prevents primarily entry of pathogen. It is the first line of defence action, very fast but not adequate. Adaptive form constitutes defensive cells and secreted immunoglobulins. It takes time to develop effectively, especially when the body sees the organism for the first time. Immunoglobulins (Ig) or antibodies are a group of proteins produced from B lymphocytes and plasma cells in response to the presence of any foreign substances. They are 5 basic types like M, A, G, E and D each with specific function. The system can produce antibody molecules, directed to about 1 million different kinds of antigens. All immunoglobulins have a similar basic structure.

Introduction Biological fluids refer to any liquid substances found within living organisms that play essential roles in physiological functions. These fluids can include blood, urine, cerebrospinal fluid, saliva, digestive juices, rumen fluid, peritoneal fluid, pleural fluid, pericardial fluid, synovial fluid, amniotic fluid, milk etc. Collection of biological fluids refers to the process of gathering various types of bodily f luids from animals for scientific study or medical purposes. This collection often involves techniques like blood draws, urine collection, cerebrospinal fluid sampling, saliva collection, etc., depending on the specific fluid and the research or diagnostic needs. These f luids are valuable for understanding the health, metabolism, genetics, and other aspects of animal biology. Collecting and analyzing these biological fluids is crucial for understanding health and disease processes, diagnosing illnesses, monitoring treatment effectiveness, and advancing medical and scientific research.

Introduction Urinalysis, the examination of normal and abnormal components of urine, is one of the most important aspect of clinical pathology that aids in accurate and timely diagnosis in veterinary practice. Urine is considered as one of the most accessible bio-fluid that can be collected using non- invasive techniques in adequate quantities. It includes the evaluation of colour, odour, turbidity, volume, pH, specific gravity, protein and glucose content, ketone bodies, blood, erythrocytes, leukocytes, epithelial cells, casts, crystal, micro-organisms, etc. Urinalysis gives us valuable information regarding the several important attributes of renal function. For example, specific gravity of urine gives valuable insights over the potential of the Henle’s loop to dilute urine and the distal convoluted tubules to concentrate urine after ruling out the extra-renal factors affecting the urine specific gravity. It is highly useful to evaluate the different types of urogenital diseases and it also provides significant information regarding several systemic disorders. It is comparatively quicker to perform and is relatively a low-cost test that could be easily done in most clinical setups.

Introduction Biochemistry is branch of life science which deals with the study of chemical reactions occurring in the living cells and organisms. The term biochemistry was first introduced by German chemist Carl Neuberg in 1903. Since biochemistry is associated with the biological reactions and energy changes associated with these reactions or transformations within the living cell, biochemistry may thus be treated as a discipline in which biological phenomenon are analysed in terms of chemistry. The branch of biochemistry for the same reason has been variously named as “Biological Chemistry” or “Chemical Biology”. Modern biochemistry has two branches descriptive and dynamic biochemistry. Descriptive biochemistry deals with qualitative and quantitative characterization of the various chemical components of cell and the dynamic biochemistry deals with the elucidation of the nature and the mechanism of reactions involving these chemical cell components. Qualitative analysis of biological sample deals with the examination of the organic or inorganic cell associated components in order to determine its composition. It denotes the presence of various biomolecules, elements or groups of elements that are present in the sampling population. It is possible to determine whether a particular component is present or absent in a sample by performing a qualitative analysis of the sample. Qualitative analysis is the identification of elements, species and/or compounds present in a sample.

Introduction Colorimetry is a scientific technique widely used across various fields to quantify the concentration of substances based on their color intensity. Colorimetry is a branch of analytical chemistry that focuses on measuring the absorbance or transmission of light by colored solutions. It utilizes the principles of optics and spectroscopy to determine the concentration of a substance in a solution based on its color intensity. This technique relies on the Beer-Lambert law, which states that the absorbance of light by a solution is directly proportional to its concentration and path length. Principles of Colorimetry The fundamental principle of colorimetry lies in the interaction of light with matter. When light passes through or is reflected off a substance, certain wavelengths are absorbed, while others are transmitted or reflected. The color we perceive is due to the wavelengths of light that are reflected back to our eyes. In colorimetry, a photometric measurement is made using a colorimeter or spectrophotometer, which quantifies the intensity of light absorbed or transmitted by a sample.