eChapters

Introduction

The nucleic acids are the molecular depots that are responsible for continuity of life by transfer of hereditary information from one generation to next. The sequence of nitrogenous bases containing programmed instruction determines the structure of every cell constituent and eventually every protein. In 1869, Friedrich Miescher, Swiss chemist, isolated an unknown phosphate-rich substance from pus cells named as nuclein, which was quite different from other organic substances like carbohydrate, protein, and fat. Altmann in 1899 ascertained that the nuclein also had some acidic characteristics and changed its name to ‘nucleic acid’. Later, nucleic acid was also isolated from salmon sperm nuclei as DNA-protaminecomplex. In 1953, James D.Watson and Francis H.C. Crick constructed the model of three-dimensional double helix structure of the DNA molecule which could successfully explain DNA replication.

Introduction

The basic components of diet include carbohydrate, protein, fat, vitamins and minerals. Vitamins are the essential nutrients which are not formed in our body and required in minute amount from the diet. Vitamins are crucial for the optimal functions of several enzymes; thus important for optimal growth and development. Vitamins perform various functions that help in regulation of metabolism, prevent chronic diseases, maintain natural appetite, mental health and immunity.

In 1912, Polish biochemist Kazimierz Funk coined the term ‘vitamine’;a substance that was present in rice polishing and foods that cured polyneuritis in birds and beriberi in humans. The name is from ‘vit’ for vital nutrient and ‘amine’ for its similarity as an amine. Vital signify that these factors are indispensable for life. Earlier they are identified and thought to contain amino groups, thus the word amine was used, which was true for thiamine but later work revealed that most of the vitamins do not have amino groups. Thus the word was shortened to vitamin in English. It should be noted that the term vitamin does not denote to some othern utrients such as essential amino acids, essential fatty acids, dietary minerals or other nutrients that contribute towards good health.

Vitamins may be defined as organic compound needed in minute amount through diet to perform specific biological functions for normal growth and health of the organisms.Vitamins should have following characteristics:

Introduction

Hormones may be defined as specific chemical molecules produced in certain specific organs called specialized cells or endocrine glands. They are delivered into the blood stream or some other body fluid in minute amounts by the circulatory system of the body and their they exerts a physiological effect at a site of action remote from its origin, regulating numerous biological activities including growth, development, reproduction, water & electrolyte balance, storage & usage of energy etc.

Introduction

Carbohydrates are the most common source of energy for all living cells, which, in presence of light, are formed by the green plants from CO₂ and water during photosynthesis. It canbe said that ‘light’ is theultimatesourceof energyrequired for all livingcells.Glucose,a monosaccharide,plays a centralroleincarbohydrate metabolismin all plants, animals and manymicroorganisms. Glucose is derived from the polysaccharides (starch, glycogen) and non-carbohydrate sources (amino acids, glycerols, etc.) during metabolism and ultimately converted either into carbondioxide and water orotherintermediateproducts.Complete oxidation of glucose to CO₂ and water provides ~2,840 kJ/mol energy. The other monosaccharides such as fructose, galactose, mannose, etc. are also important molecules in carbohydrate metabolism.

Introduction

The diverse cluster of naturally occurring organic compounds including fats, oils, fatty acids, waxes, phospholipids, eicosanoids, terpenes, steroids and fat soluble vitamins that do not prefer to interact with water but soluble in non-polar organic solvents like ether, chloroform, benzene, acetone, are called as lipids. The main functions of lipids in biological system include storage and transport of metabolic fuel, structural component of cell membranes, insulation & protection of vital organs from shock and carrier of fat soluble vitamins. Contradictory to proteins,lipids are not polymers in nature and are hydrophobic due to presence of a long hydrophobic chain. Apart from this, lipids also act as precursor molecules for several pigments, hormones and signaling molecules.

Introduction

Proteins are the most abundant organic compounds constituting major part of the body. Chemically, proteins are nitrogen containing macromolecules and polymers of L α-amino acids, which serve a wide range of structural and biological functions in animal body. For example, connective tissue made up of collagen, metabolicenzymes, neuro transmitters,signal in gmolecules, structural components of cell membranes and cell organelles, etc. all are chemically proteins.

Before goinginto the details of protein metabolism, first, we need to understand that there are majorly two sources of proteins in our body: dietary protein and body protein. Dietary protein is taken in diet, while body protein indicates the protein and amino acids synthesized in animal body to fulfill the requirements for growth and development. The digestion of proteins will not be discussed here as it has been described in detail in chapter 12. Dietary protein is digested in presence of several enzymes such as trypsin, pepsin, chymotrypsin, aminopeptidases and carboxypeptidases and is converted into mono-, di- and oligopeptides in stomach and small intestine; and finally converted into amino acids. These amino acids are transported to the systemthrough intestinal mucosa via active transport, from where they enter into the cells for further metabolism. Therefore, ‘metabolismof proteins’ is more appropriatelylearnt as ‘metabolism of amino acids’.

Introduction

The basic physiological structures of mammary glands in all species are almost same and are located externally in order to fulfill the milk requirement of neonates after parturition. The process of secretion of milk from the mammary glands is known as lacto genesis. Milk provides an almost complete nutrition to neonates from birth till weaning period. It is a complex mixture of various constituents like:

Lipids such a striacyl glycerols(TAG),phospholipids,cholesterols and other sterols, free fatty acids and fat-soluble vitamins

Carbohydrates such as lactose, oligosaccharides

Proteins such a scaseins, α-lactalbumin, β-lactoglobulin, immunoglobulin’s, bovine serum albumin, lactoferrin, lysozyme, enzymes, hormones and growth factors

Non-protein nitrogenous compounds like urea, creatine, creatinine, uric acid and amino acids

Major and minor minerals, water-soluble vitamins and cells (leucocytes, macrophages, and epithelial cells).

Introduction

Nutrition, a basic human need, is a critical part of health and development. Nutrition can be defined as the intake of food, deliberated in relation to the body’s dietary needs. On one hand, good nutrition – an adequate, well balanced diet combined with regular physical activity – is a foundation of good health, whereas,poor nutritionleads toreducedproductivity,impairedmental andphysical development, increased susceptibility to disease, and reducedimmunity. According to WHO, under-nutrition, together with vitamin and mineral deficiencies accounts for one-third of all child deaths and impairs healthy development and lifelong productivity. At the same time, sedentary lifestyles, demographic shifts, urbanization and the liberalization of markets have steered the world population to being overweight along with risk of chronic diseases like hypertension, dyslipidemia, type 2 diabetes, coronaryheart disease, stroke, etc.; thus, resulting in a double burden of malnutrition.

To address this dual burden of malnutrition, individuals needaccess to sufficient and good quality food; but focussing solely on food security is unlikely to solve the problem of global malnutrition. The challenges of malnutrition cannot be solvedjustbyincreasingfoodproductioninordertoimprove healthand nutritional status of the population. To resolve such challenges, awareness about food choices for optimal health plays a pivotal role among population.

Human nutrition is the science of understanding food; its component; intake; and how it is related to health, growth, development and diseases. Human nutrition involves the study of ingestion, digestion, absorption and assimilation of the nutrients; their metabolic functions, deficiency or excess disease as well as their regulation through several factors such as choosing particular food components/nutraceuticals or physical activity.

Introduction

Nutrition is the fundamental pillar of life and an essential foundation of human and national development. Rightfrom the earliest stage of human development, the fetal stage, at birth, infancy, childhood, adolescence, adulthood and old age, nutrition forms the basis for survival, performance, mental and physical development & economic and social development.Nutritional deficiencies during pregnancy, fetal and early postnatal life can have a negative impact not only on the subsequent growth and development but can also lead to changes in metabolic regulation and homeostasis.

Introduction

Nutritive value of any food indicates the calories content as well as quality attributes. Macronutrients such as carbohydrates, fats and proteins provide energy by4-9-4 rule. It meanstheyprovide 4,9 and 4 kcal/genergy, respectively, when oxidized completely. Though micronutrientssuch as vitaminsandminerals do not provide any calories, they are essential for the enzymatic activity and metabolic reactions.

ATP or energy is measured in terms of ‘calories’ or ‘joule’. One calorie is the amount of heat required by 1g of water to increase its temperature from 14.5 to 15.5°C under standard conditions. Nutritive value of any food can be measured on shelf usingcalorimeter, in which food is completelyoxidized under specified conditions and converted into CO₂ and water.

Introduction

Digestion may be defined as the hydrolytic process carried out by various enzymes for breaking down complex food components such as proteins, fats and carbohydrates into simpler molecules like amino acids, fatty acids and monosaccharides, respectively. Whereas, absorption may be defined as the movement ofthese simple soluble digested food componentsalongwithvitamins, minerals and water from gastrointestinal track into the circulatory system.

The process of digestion starts from oral cavity (mouth) and ends at large intestineincluding tongue, teeth, jaws,secretions from salivaryglands (parotids, sub maxillary or submandibular and sublingual glands), pharynx, esophagus, stomach, small intestine and digestive enzymes secreted from pancreas and liver.

Introduction

There are manypeople all over the world who have a certain level of sensitivity or intolerance towards milk and milk products. The reactions to milk which involve the immune systemare termed as milkallergy, whereas, difficulty in the digestion of the milk and milk products is known as milk intolerance. Milk intolerance occurs due to malabsorption of milk sugar (lactose) in intestine, a condition in which lactose is not digested into its monomers (galactose and glucose) due to lower activity or insufficiency of lactase enzyme. Inability to digest lactose, which is a disaccharide present only in milk, is specifically known as lactose intolerance. However, hypersensitivity involves the adverse immune reaction(allergic reaction) inthe body causeddue to the ingestion of milk proteins. Milk and milk products are major source of basic as well as essential nutrients and cannot be skipped from the diet of the individual. It is a rich source of calcium,which is essential for the growth and reformationof bones. The decline in calcium may lead to thin, fragile bones that break easily, a condition called osteomalacia or osteoporosis in women. Thus, it is a matter of concern for both children andadults whoare allergic or intolerant towards milk and milk products and not getting enough calcium and other nutrients in diet. This chapter would provide more insight about milk intolerance and milk allergy/hypersensitivity and how to deal with it.

Introduction

Spectacular accomplishment in every sector has enabled India to be amongtop achieving nations. However, every section of the society is not benefited by these achievements and problem of malnutrition still remains unresolved. Malnutrition is a common problem faced by underdeveloped and developing countries suchas Philippines, Nepal, Sudan,Tanzaniaand Indiasincelongback. Malnutrition includes undernutrition(wasting,stunting,underweight),inadequate vitamins or minerals as well as overweight, obesity and resulting diet-related non communicable diseases(NCDs). As per the latest report of World Health Organization, 52 million children under 5 years of ageare wasted, 17 million are severely wasted and 155 million are stunted, while 41 million are overweight or obese (WHO, 2018). More than 50% women of marriage age are suffering from anemia. If women are malnourished at the time of pregnancyand delivery, the babybornface theproblems such asphysical retardation,sensitive tocommon infections, reduced cognitive abilities, reducedmental development, etc. As per the World Health Organization (WHO) guidelines, starting from the date of conceiving a child, the first 1000 days are a critical window from nutrition point ofview.Unfortunately, inseveral regions of developingcountries includingIndia, neither the mother nor the babyis provided with the right quantity and qualityof food during this window period. Therefore, it is important for the policymakers to identifymalnutrition at an earlystage for timelyplanningand implementation of various intervention strategies at the community, village, and district level. NitiAyog, Government of India (GoI) (previously known as Planning Commission), in an effort to eliminate malnutrition,regularlyplans several short and longtermnutritionalprogrammesand policies.In thischapter,we willdiscuss some of these policies launched since independence and their impact in combatingmalnutrition.

Introduction

The dairy sector is one of the most important food sectors, which introduced the physical, chemical, microbiological and sensorial criteria duringprocessing steps and in the final dairy products. Several agents/ingredients of non-dairy origin are commonly used to maintain the quality of milk and milk products during processing, transportation and storage. In general, such ingredients are known as food additives and it can be antioxidants, coloring agents, flavoring compounds, preservatives(naturals and synthetic),artificialsweeteners, vitamins, minerals, stabilizers, emulsifiers and curing agents. From the safety point of view, some toxic agents can come into contact of dairy products duringmilking, storage or processing; such as fungal toxins, heavy metals, antibiotics or radionuclide’s, etc., which need to be identified and processed accordingly. Although addition of food additives in food/dairy product is controlled under country specific food laws or Codex Alimentarius Commission (CAC), few dairyproducts such as butter and unflavored fermented milk products are highly restricted for food additives.

Plant physiology is a sub-discipline of botany concerned with the functioning, or physiology of plants. Closely related fields include plant morphology (structure of plants), plant ecology (interactions with the environment), phytochemistry (biochemistry of plants), cell biology, genetic, biophysics and molecular biology. Fundamental processes such as photosynthesis, respiration, plant nutrition, plant hormone functions, tropism, nastic movements, photoperiodism, photo-morphogenesis, circadian rhythms, environmental stress physiology, seed germination, dormancy, stomata function and transpiration, both parts of plant water relations, are studied by plant physiologists. The field of plant physiology includes the study of all the internal activities of plants those chemical and physical processes associated with life as they occur in plants. This includes study at many levels of scale of size and time. At the smallest scale are molecular interactions of photosynthesis and internal diffusion of water, minerals, and nutrients. Major sub disciplines of plant physiology include phytochemistry (the study of the biochemistry of plants) and phytopathology (the study of disease in plants). The scope of plant physiology as a discipline may be divided into several major areas of research.

Tissue or cell samples from a living organism, different cell cultures grown in a laboratory incubator under controlled conditions, homogenates or extracts of cells and tissues, solutions of isolated and purified components (e.g. proteins, nucleic acids) can all be referred to as biological samples. As the medium of life is water, the majority of biological samples can be defined as aqueous solutions with one or more components, colloidal systems, or water-based suspensions (e.g. bacterial cells dispersed in a liquid medium). Consequently, most biochemical experiments also take place in aqueous environments. Different solids (e.g. chemical substances obtained from different companies, synthetic oligonucleotides or peptides) are also often necessary for biochemical research. In most cases, solids are dissolved in water (or sometimes in other solvents) prior to the experiments. Therefore, the methods of preparing solutions and measuring accurately the weight of the required solids will also be discussed below. Sometimes we use gases in the laboratory. These can be stored in gas cylinders (e.g. O₂), in Dewar flasks in liquid state (e.g. liquid nitrogen), or dissolved in water (e.g. HCl or NH₃). By working with gases it is very important to follow all safety instructions to avoid fire, explosions, frostbite or (in case of inhalation) asphyxia or poisoning.

Units/measures are used to specify quantities. Every unit has a well-defined standard basic value, which is used as a reference in measurements. The units used in scientific practice constitute a scientifically established system, SI (Système International). Although only SI units are official , numerous non-SI units are still widely used (calorie, Ångström, Celsius etc.). We distinguish two types of quantities with two corresponding types of SI units. The base quantities cannot be derived from other quantities. Many of these are used in biochemistry (names of units and their symbols are given in brackets) to quantify the mass (gram, g), the length (meter, m), the time (second, s), the temperature (kelvin, K) and the charge (coulomb, C). Much larger is the group of derived quantities. Of these, the various units of concentration (to characterise the abundance of materials in solutions and other mixtures), volume and energy are the ones most frequently used in biochemistry. It is important to note that the terms mass and weight are often used interchangeably as alternatives. Technically, however, they have different meanings. The mass is the total quantity of matter in an object, which comes from the mass of all of its protons and neutrons, although not simply additively. Weight is a measure of the gravitational force exerted on an object. As the mass of protons and neutrons is the unit mass, their total mass in an object (e.g. the mass of a molecule, the molar mass) is a unitless number (e.g. the molar mass of water is 18). In other words, the molar mass is a relative number that would reflect the number of protons and neutrons in an atom or molecule, if the masses of protons and neutrons were additive. We make mass measurable by expressing it in grams because this way we can handle it as weight and measure it with a balance, the device developed for this purpose. 

As homogeneity is a basic criterion, it is important to know the solubility of solutes, which is a temperature dependent property. Besides temperature, solubility is influenced by the acidity (pH) of the solvent due to the acid-base character of the solute. Bases tend to dissolve better in acidic solutions, whereas acids do in basic solutions. Therefore, one often needs to change the pH of solutions accordingly. As the most widely used concentration units (molarity, w/v% and v/v%) refer the amount of solute in a given volume of the solution, it is the volume of the complete solution that must be set to the desired (calculated) value thus, one must consider not only the solvent but the solute(s) as well. Another reason why one must add the solute(s) to an amount of solvent which is less than the final volume might be that one will need to set the pH subsequently in order to enhance solubility and/or to reach a desired pH value. The volume of acid or base solutions used for pH setting is usually not known in advance and is not negligible. If the solute was initially dissolved in the final desired volume, one would exceed this volume during pH setting (even if the volume of the solute is negligible) and, thus, the solution would not have the desired (calculated) concentration but a smaller (and mostly unknown) one. Thus, according to the correct procedure, one must take into consideration the fact that the final volume will contain the volume of the buffering component. value particularly in the case of dissolving proteins, which have a tendency to stick to the bottom of the dish, thereby making dissolution substantially slower.

A buffer is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. Its pH changes very little when a small amount of strong acid or base is added to it and thus it is used to prevent changes in the pH of a solution. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. Many life forms thrive only in a relatively small pH range so they utilize a buffer solution to maintain a constant pH. One example of a buffer solution found in nature is blood.

Carbon assimilation or carbon fixation is the conversion of inorganic carbon (carbon dioxide) to organic compounds by living organisms. The most prominent example is photosynthesis, although chemosynthesis is another form of carbon fixation that can take place in the absence of sunlight. Organisms that grow by fixing carbon are called autotrophs. Autotrophs include photoautotrophs, which synthesize organic compounds using the energy of sunlight, and lithoautotrophs, which synthesize organic compounds using the energy of inorganic oxidation. Heterotrophs are organisms that grow using the carbon fixed by autotrophs. The organic compounds are used by heterotrophs to produce energy and to build body structures. “Fixed carbon”, “reduced carbon”, and “organic carbon” are equivalent terms for various organic compounds.

A carbohydrate is a large biological molecules, or macromolecules, consisting of carbon (C), hydrogen (H), and oxygen (O) atoms, usually with a hydrogen : oxygen atom ratio of 2:1 (as in water); in other words, with the empirical formula C_m(H₂O)_n (where m could be different from n). Some exceptions exist; for example, deoxyribose, a sugar component of DNA, has the empirical formula C₅H₁₀O₄. Carbohydrates are technically hydrates of carbon; structurally it is more accurate to view them as polyhydroxy aldehydes and ketones.

The term is most common in biochemistry, where it is a synonym of saccharide. The carbohydrates (saccharides) are divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. In general, the monosaccharides and disaccharides, which are smaller (lower molecular weight) carbohydrates, are commonly referred to as sugars. While the scientific nomenclature of carbohydrates is complex, the names of the monosaccharides and disaccharides very often end in the suffix -ose. For example, grape sugar is the monosaccharide glucose, cane sugar is the disaccharide sucrose, and milk sugar is the disaccharide lactose.

Nitrogen assimilation is the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment. Organisms like plants, fungi and certain bacteria that cannot fix nitrogen gas (N₂) depend on the ability to assimilate nitrate or ammonia for their needs. Other organisms, like animals, depend entirely on organic nitrogen from their food.

Plants absorb nitrogen from the soil in the form of nitrate (NO₃ ^-) and ammonia (NH₄). In aerobic soils where nitrification can occur, nitrate is usually the predominant form of available nitrogen that is absorbed. However this need not always be the case as ammonia can predominate in grasslands and in flooded, anaerobic soils like rice paddies. Plant roots themselves can affect the abundance of various forms of nitrogen by changing the pH and secreting organic compounds or oxygen. This influences microbial activities like the interconversion of various nitrogen species, the release of ammonia from organic matter in the soil and the fixation of nitrogen by non-nodule-forming bacteria.

Proteins are large biological molecules, or macromolecules, consisting of one or more chains of amino acid residues. Proteins perform a vast array of functions within living organisms, including catalysing metabolic reactions, replicating DNA, responding to stimuli, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in folding of the protein into a specific three-dimensional structure that determines its activity. A polypeptide is a single linear polymer chain derived from the condensation of amino acids. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids; however, in certain organisms the genetic code can include selenocysteine and, in certain archaea-pyrrolysine. Shortly after or even during synthesis, the residues in a protein are often chemically modified by post translational modification, which alters the physical and chemical properties, folding, stability, activity, and ultimately, the function of the proteins. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors. Proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes.

Like other biological macromolecules such as pollysaccharides and nucleic acids, proteins are essential parts of organisms and participate in virtually every process within cells. Many proteins are enzymes that catalyse biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape. Other proteins are important in cell signalling, immune responses, cell adhesion, and the cell cycle. Proteins are also necessary in animals’ diets, since animals cannot synthesize all the amino acids they need and must obtain essential amino acids from food. Through the process of digestion, animals break down ingested protein into free amino acids that are then used in metabolism.

Amino acids are biologically important organic compounds composed of amine (-NH₂) and carboxylic acid (-COOH) functional groups, along with a side-chain specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, though other elements are found in the side-chains of certain amino acids. About 500 amino acids are known and can be classified in many ways. They can be classified according to the core structural functional groups’ locations as alpha- (?-), beta- (β), gamma- (?), or delta- (δ-) amino acids; other categories relate to polarity, pH level, and side-chain group type (aliphatic, acrylic, aromatic, containing hydroxyl or sulphur, etc.). In the form of proteins, amino acids comprise the second-largest component (water is the largest) of human muscles, cells and other tissues. Outside proteins, amino acids perform critical roles in processes such as neurotransmitter transport and biosynthesis. Amino acids having both the amine and the carboxylic acid groups attached to the first (alpha-) carbon atom have particular importance in biochemistry. They are known as 2-, alpha-, or ?-amino acids (generic formula H₂NCHRCOOH in most cases where R is an organic substituent known as a “side-chain”); often the term “amino acid” is used to refer specifically to these. They include the 22 proteinogenic (“protein-building”) amino acids, which combine into peptide chains (“polypeptides”) to form the building-blocks of a vast array of proteins. These are all L-stereoisomers (“left-handed” isomers), although a few D-amino acids (“right-handed”) occur in bacterial envelopes and some antibiotics. Twenty of the proteinogenic amino acids are encoded directly by triplet codons in the genetic code and are known as “standard” amino acids. The other two (“non-standard” or “non-canonical”) are pyrrolysine (found in methanogenic organisms and other eukaryotes) and selenocysteine (present in many noneukaryotes as well as most eukaryotes). For example, 25 human proteins include selenocysteine (Sec) in their primary structure, and the structurally characterized enzymes (selenoenzymes) employ Sec as the catalytic moiety in their active sites. Pyrrolysine and selenocysteine are encoded via variant codons; for example, selenocysteine is encoded by stop codon and SECIS element. Codon–tRNA combinations not found in nature can also be used to “expand” the genetic code and create novel proteins known as alloproteins incorporating non-proteinogenic amino acids.

Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others. The main biological functions of lipids include storing energy, signalling, and acting as structural components of cell membrane. Lipids have applications in the cosmetic and food industries as well as in nanotechnology.

Lipids may be broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or “building-blocks”: ketoacyl and isoperen groups. Using this approach, lipids may be divided into eight categories:fatty acids, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids and polyketides (derived from condensation of ketoacyl subunits); and sterol lipids and prenol lipids (derived from condensation of isoprene subunits).

Although the term lipid is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides. Lipids also encompass molecules such as fatty acids and their derivatives (including tri-, di-, monoglycerides and phospholipids), as well as other sterol containing metabolites such as chloestrol. Although humans and other mammals use various biosynthetic pathways to both break down and synthesize lipids, some essential lipids cannot be made this way and must be obtained from the diet.

Plant nutrition is the study of the chemical elements and compounds that are necessary for plant growth, and also of their external supply and internal metabolism. The criteria for an element to be essential for plant growth:

In its absence the plant is unable to complete a normal life cycle; or

That the element is part of some essential plant constituent or metabolite.

Biological pigments, also known simply as pigments or biochromes are substances produced by living organisms that have a colour resulting from selective colour absorption. Biological pigments include plant pigments and flower pigments. Many biological structures, such as skin, eyes, fur and hair contain pigments such as melanin in specialized cells called chromatophores.

Pigment colour differs from structural colour in that it is the same for all viewing angles, whereas structural colour is the result of selective reflection or iridescence, usually because of multilayer structures. For example, butterfly wings typically contain structural colour, although many butterflies have cells that contain pigment as well.

In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of a hydroxyl group (—OH) bonded directly to an aromatic hydrocarbon group. The simplest of the class is phenol, which is also called carbolic acid C₆H₅OH. Phenolic compounds are classified as simple phenols or polyphenols based on the number of phenol units in the molecule.

Plant secondary metabolism produces products that aid in the growth and development of plants but are not required for the plant to survive. Secondary metabolism facilitates the primary metabolism in plants. This primary metabolism consists of chemical reactions that allow the plant to live. In order for the plants to stay healthy, secondary metabolism plays a pinnacle role in keeping all the of plants’systems working properly. A common role of secondary metabolites in plants is defense mechanisms. They are used to fight off herbivores, pests, and pathogens. Although researchers know that this trait is common in many plants it is still difficult to determine the precise role each secondary metabolite. Secondary metabolites are used in anti-feeding activity, toxicity or acting as precursors to physical defense systems.

Plant hormones (also known as phytohormones) are chemicals that regulate plant growth, which are termed ‘plant growth substances’.

Plant hormones are signal molecules produced within the plant, and occur in extremely low concentrations. Hormones regulate cellular processes in targeted cells locally and, when moved to other locations, in other locations of the plant. Hormones also determine the formation of flower, stems, leaves, the shedding of leaves, and the development and ripening of fruit. Plants, unlike animals, lack glands that produce and secrete hormones. Instead, each cell is capable of producing hormones. Plant hormones shape the plant, affecting seed growth, time of flowering, the sex of flowers, senescence of leaves, and fruits. They affect which tissues grow upward and which grow downward, leaf formation and stem growth, fruit development and ripening, plant longevity, and even plant death. Hormones are vital to plant growth, and, lacking them, plants would be mostly a mass of undifferentiated cells. So they are also known as growth factors or growth hormones..

Phytohormones are found not only in higher plants, but in algae too, showing similar functions, and in microorganisms, like fungi and bacteria, but, in this case, they play no hormonal or other immediate physiological role in the producing organism and can, thus, be regarded as secondary metabolites.

Nucleic acids are polymeric macromolecules, or large biological molecules, essential for all known forms of life. Nucleic acids, which include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are made from monomers known as nucleotides. Each nucleotide has three components: a 5-carbon sugar, a phosphate group, and a nitrogenous base. If the sugar is deoxiribose, the polymer is DNA. If the sugar is ribose, the polymer is RNA. Together with proteins, nucleic acids are the most important biological macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information—in other words, information is conveyed through the nucleic acid sequence, or the order of nucleotides within a DNA or RNA molecule. Strings of nucleotides strung together in a specific sequence are the mechanism for storing and transmitting hereditary, or genetic, information via protein synthesis.

The term nucleic acid is the overall name for DNA and RNA, members of a family of biopolymers, and is synonymous with polynucleotide. Nucleic acids were named for their initial discovery within the nucleus, and for the presence of phosphate groups (related to phosphoric acid). Although first discovered within the nucleus of eukaryotic cells, nucleic acids are now known to be found in all life forms as well as some nonliving entities, including within bacteria, archaea, mitochondria, chloroplasts, viruses and viroids. All living cells contain both DNA and RNA (except some cells such as mature red blood cells), while viruses contain either DNA or RNA, but usually not both. The basic component of biological nucleic acids is the nucleotide, each of which contains a pentose sugar (ribose or deoxyribose), a phosphate group, and a nucleobase. Nucleic acids are also generated within the laboratory, through the use of enzymes (DNA and RNA polymerases) and by solid-phase chemical synthesis. The chemical methods also enable the generation of altered nucleic acids that are not found in nature, for example peptide nucleic acids.

A vitamin is an organic compound required by an organism as a vital nutrient in limited amounts. An organic chemical compound (or related set of compounds) is called a vitamin when it cannot be synthesised in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on the circumstances and on the particular organism. For example, ascorbic acid (vitamin C) is a vitamin for humans, but not for most other animals. Supplementation is important for the treatment of certain health problems but there is little evidence of benefit when used by those who are otherwise healthy.

By convention, the term vitamin includes neither other essential nutrients, such as dietary minerals, essential fatty acids, or essential amino acids (which are needed in larger amounts than vitamins) nor the large number of other nutrients that promote health but are otherwise required less often. Thirteen vitamins are universally recognized at present. Vitamins are classified by their biological and chemical activity, not their structure. Thus, each “vitamin” refers to a number of vitamer compounds that all show the biological activity associated with a particular vitamin. Such a set of chemicals is grouped under an alphabetized vitamin “generic descriptor” title, such as “vitamin A”, which includes the compounds retinal, retinol, and four known carotenoids. Vitamers by definition are convertible to the active form of the vitamin in the body, and are sometimes inter-convertible to one another, as well.

Vitamins have diverse biochemical functions. Some, such as vitamin D, have hormone-like functions as regulators of mineral metabolism, or regulators of cell and tissue growth and differentiation (such as some forms of vitamin A). Others function as antioxidants (e.g., vitamin E and sometimes vitamin C).

India is an agricultural country and nearly 70% of its population is dependent directly or indirectly on agriculture and related activities. At present, about 173 million hectares of land is under agriculture of which about 143 million hectare are cultivated without fallow. Mounting pressures of teeming population and shrinking land (due to urbanization) have necessitated the production of increasingly more food per unit area. In the efforts to increase the food production and make the country self-sufficient in food grains, modern technology adopted since ‘Green Revolution’ in the middle sixties has paid a significant role. Higher yields in almost all crops were possible with exotic and high yielding genotypes and availability of seeds, heavy doses of fertilizers, frequent irrigation, labour and repeated applications of pesticides. However, several genotypes particularly hybrids proved to be susceptible to pests and disease pathogens. Insect-pests, diseases and weeds are important biotic-constraints inflicting 20-25% losses in agricultural production. Farmers were therefore compelled to use pesticides extensively and frequently.

Plant protection is an integral part of the crop production and pesticides proved to be valuable means in plant protection to ensure plenty food. However, some of the pesticides are highly hazardous and their residue remains undetected and posses risk to human safety and health. Moreover, the repeated and incorrect applications without following need-based criteria have resulted in several secondary side effects ². For instance, increased resistance of pests to insecticides, harmful to beneficial and non-target insects and animals, undesirable effects on crop plants and environmental hazards. Safety has become a major worry in factories and outside the working places. Besides these, repeated and heavy pesticide applications add to the cost of production and misery to farmer. These ill effects of synthetic pesticides have aroused interest in alternate methods of plant protection.

Introduction

In agriculture and public health sectors, a variety of pesticides are still in uses that are toxic chemicals and having broad-spectrum actions. They kill target species but also harm the ecosystem seriously by affecting desirable organisms, thus, badly impairing prey-predator relationship. Most of these pesticides are persistent or non-biodegradable and hence exhibit biological magnification by accumulating at higher concentration in the organism, which are on the top of the food chain. The other drawbacks of repeated use of pesticides are eradication of natural enemies of pests, increased level of pesticide residues in soil, water, food and fodder crops, resistance of pests to pesticides and resurgence of minor pests in addition to the environmental pollution. It is clear that once used pesticide may persist, somewhere causing serious harm to the mankind and his ecosystem.

The increasing incidence of pesticide harms is fueling the need for new pesticides, which are toxicologically safe, more selective and efficacious and environment-friendly. Now the natural compounds, thus, have increasingly become the focus of those interested in discovery of pesticides. Tens of thousands of secondary products of plants have been identified and there are estimates that hundreds of thousands of these compounds exist. There is growing evidence that most of these compounds are involved in the interaction of plants with other species-primarily the defense of the plants from plant pests. Thus, these secondary compounds represent a large reservoir of chemical structures with biological activity. This resource is largely untapped for use as pest management agents^3, 4. The extraction of such chemicals from plants and derivatives of potent compounds are being encouraged all over the world under the Integrated Pest Management (IPM) approaches. The natural compounds and their synthetic derivatives are more selective in action, completely biodegradable and environment-friendly. In short, natural ways of pests control have already been established and are receiving much attention these days.

Introduction

In man’s continued effort to enhance food production, new high yielding crop varieties and new techniques for crop and field management are being constantly evolved resulting in a parallel increase in disease occurrence which calls for their efficient management. Of the various management strategies available for disease management, the chemical strategies have so far dominated our thinking. Over emphasis on chemical control of plant diseases has caused serious imbalances in the agro-ecosystem^1-2.

The shift to exploration of non-chemical strategies is likely to correct the imbalance in our approach and subsequently improve the understanding of Integrated Disease Management (IDM). IDM is defined as ‘a disease management system that utilizes all suitable techniques in a compatible manner to reduce and maintain pest pathogen population at levels below those causing economic injury.’ Fungi are the important group of pathogens.

In continuation of our work on natural pest management agents the present investigation aims at the preparation of different types of aqueous extracts of locally available four Indian medicinal plants viz., Datura stramonium Linn (Datura), Ricinus communis Linn. (Castor), Vitex trifolia Linn. (Nirgudi) and Nerium indicum Mill. (Kanher); study of stability of these extracts at room temperature; and evaluation of their anti-fungal potencies. This study will help to preserve and increase the pest management potency and efficacy of natural products.

Introduction

The biological systems on the earth are in a dynamic equilibrium. In this attempt to live comfortably man disturbs this equilibrium in many, one of which is the cultivation of crop plants to meet his requirements for food, clothing and shelter. Intensive and extensive n of crop plants provides not only better crops but also better ties for pests and diseases to attack these crops. The greater loss due to the pests and diseases, the greater the attempt to these damages. Bacteria are one of the important disease since time immemorial. Bacteria are found in every ble habitat. They are unicellular, but display a variety of ‘cal forms.

The present investigation on the botanicals  has been aimed at preparation of different types of aqueous extracts of locally available medicinal plants viz., Datura stramonium (Datura), Ricinus Castor), Vitex trifolia (Nirgudi) and Nerium indicum (Kanher); the study concentration and stability of these extracts at room temperature; and evaluation of their anti-bacterial activities. This study will be helpful to preserve and increase the pest management potency and efficiency of plant derived products.

Introduction

There are a number of estimates of post-harvest losses. The most conservative estimates for the handling losses at about 10 per cent, a quantity good enough to feed at least 60 million people. Storage loss occurs due to quantitative and qualitative damages caused by insects, mites, fungi, rodents, birds, heat, moisture, etc. Several hundred insect species have been reported to be associated with stored grains and milled and processed foods, but some 50 of these species are considered injurious. Under Indian conditions, the most important insect pests of stored grains are Sitophilus oryzae (Rice weevil), Tribolium castaneum (Red flour beetle), Rhizopertha dominica (Lesser grain borer), Callasobruchus spp. (Pulse beetle), etc.

The use of repellents to ward off insects has been a very old practice of mankind. The simple fly swatters, feather dusters, hand fans, mosquito nets etc., are some of the physical repellants still in use. In our own country, mustard oil or turmeric (haldi) water is also used as a mosquito repellent. Fire and smoke are the two oldest insect repellents known to man. To get rid of wasp nests from our dwelling or ward off honeybees during honey extraction, smoke is normally employed. Similarly sandal dhoop is often burnt to purify air (i. e. to ward off insects) in our houses.

Chemicals that prevent insect damage to plants or animals by rendering them unattractive or offensive are called repellents. A more broad-based definition would be: non-poisonous or mildly poisonous chemicals that induce avoiding (oriented movements in insects away from their source. Repellents are more important in the protection of man and his animals from insect attacks than in the protection plants.

Introduction

The food problem in the world is expected to become more serious if the world population keeps growing at the present rate. Out of various strategies to solve the problem, the post-harvest handling of the grains is of paramount importance. Tribolium species is major pest of stored grain and grain products in the tropics. Control of this insect relies heavily on the use of synthetic insecticides, which has led to many problems such as increasing costs of application, pest resurgence, pest resistance to pesticides and lethal effects on non-target organisms in addition to direct toxicity to users and disturbances of the environment. Thus, insecticides of natural origin are rational alternatives of synthetic insecticides. Several botanicals, natural products and their derivatives have been reported and exhibit better efficacy and potency against the stored grain pests.

In the present investigation, an attempt has also made to test ovicidal, larvicidal and adult emergence suppression potentials of the extracts of some of the locally available Indian medicinal plant viz., Datura stramonium, Ricinus communis, Vitex trifolia and Nerium indicum against T. castaneum against T. castaneum, commonly called as Red flour beetle.

Since the wide introduction of organochlorines and other synthetics in early 50’s farmers have heavily relied on the chemical pesticides for pest control. Over emphasis on chemical control has caused serious imbalances in the agro-ecosystem. The enormous quantities of chemicals, poisonous to microbial life, that fall on earth gets mixed up well with soil. Some problems like non-target effects of chemicals as well as latrogenic diseases are being experienced. Coupled with these, the increasing awareness of impeding pollution, health hazards and development of resistance have intensified the search for alternative strategies.

In the present investigation, the attempts have been made to test the stability and pest management efficacy of the plant extracts of some Indian medicinal plants, namely, Datura stramonium, Ricinus communis, Vitex trifolia and Nerium indicum. In the earlier chapters detailed methodologies and the results have been elaborated. This chapter embodes the comprehensive inter- and intra-comparative results and discussion on the basis of selected plants, extraction media, pest species and bioassay followed by conclusions.

The hot sterilized water extracts of R. communis were found to be more stable (i.e. 20 days to start the fermentation). In overall study the plant extracts were stable or viable means active for three to four weeks only. In most cases, the activity of cold and hot water extracts was found to be increasing with fermentation however the decrease in the activity of some extract was also observed.

The highest mean anti-fungal activity was reported for R. communis extracts followed by D. stramonium and N. indicum aqueous extracts, whereas no any anti-fungal potency was reflected by V. trifolia against test fungi species. R. communis and N. indicum extracts, the cold water method extraction showed greater positive effects in terms of mean anti-fungal potency as compared to the hot water extracts. The water extraction of D. stramonium was found to be more effective in anti-fungal activity study.

WATER IS VERY SPECIAL IN BIOLOGY

Most abundant chemical of life

Special properties:

Cells Contain 4 Major Types of Giant Molecules (Macromolecules, Polymers)

Carbohydrates

Lipids

Proteins

Nucleic Acids

BIOLOGICAL POLYMERS ARE MADE FROM ABOUT 60 SMALL BUILDING BLOCKS

Cells contain thousands of types of giant molecules (macromolecules, polymers)

Polymers are macromolecules made from a single building block molecule Most of the macromolecules are made from about 60 types of small building block molecules

Most macromolecules are linear: building blocks linked head to tail- a few have branches (some polysaccharides)

This is what you would get if you heated cells in hydrochloric acid overnight at 110 degrees C:

ALL MATTER IS IN MOTION

Everything moves:

In the atom electrons rotate around the nucleus

In gases, liquids and even solids molecules move away from other molecules

An accumulation of matter (i.e., a baseball) can move as a unit

The average velocity of movement is the distance travelled divided by the time

Bodies in motion have energy; the faster the velocity the more energy

ENZYMES

Enzymes are the heart of Biochemistry

Protein based catalysts.

Enormously effective catalysts: typically enhance rates by 10⁶ to 10¹² fold.

Operate under mild conditions: 0 - 100 °C (or perhaps even 300+ °C for some bacteria in deep ocean), 20 - 40 °C for most organisms; and low pressures (atmospheric).

Very specific: Generally catalyze reaction for a very restricted group of molecules, sometimes for a single naturally occurring molecule of a single chirality.

There are other groups that contribute to the reactivity of enzymes beside amino acid residues.

These groups are called cofactors - chemicals required by apoenzymes (inactive) to become holoenzymes (active).

There are two types of cofactors:

1. Essential ions - metal ions -inorganic
2. Coenzymes - organic molecules that act as group-transfer reagents (accept or donate groups)- can also be H⁺ and/or e^-

Both provide reactive groups not found on amino acids side chains.

Coenzymes can be either cosubstrates (loosely bound to enzyme; is altered, then regenerated) or prosthetic groups (tightly bound to enzyme).

Coenzymes can be classified by their source:

ALL LIVING ORGANISMS ARE MADE UP OF UNITS CALLED CELLS

All living creatures are made from 1 or more cells

All cells are produced from previously existing cells (no spontaneous generation)

All cells appear to be descended from the first cell which existed about 4 billion years ago

For a species to exist its reproductive cells must be potentially immortal (no aging)

Our bodies start from a single cell and contain about 100,000,000,000,000 (10^14) cells at maturity

I. WALL COMPONENTS – CHEMISTRY

The main ingredient in cell walls are polysaccharides (or complex carbohydrates or complex sugars) which are built from monosaccharides (or simple sugars). Eleven sugars are common in these polysaccharides including like glucose and galactose. Carbohydrates are good building blocks because they can produce a nearly infinite variety of structures. There are a variety of other components in the wall including protein, and lignin. Let’s look at these wall components in more detail:

A. Cellulose: β1,4-glucan (structure provided in class). Made of as many as 25,000 individual glucose molecules. Every other molecule (called residues) is “upside down”. Cellobiose (glucose-glucose disaccharide) is the basic building block. Cellulose readily forms hydrogen bonds with itself (intra-molecular H-bonds) and with other cellulose chains (inter-molecular H-bonds). A cellulose chain will form hydrogen bonds with about 36 other chains to yield a microfibril. This is somewhat analogous to the formation of a thick rope from thin fibers. Microfibrils are 5-12 nm wide and give the wall strength - they have a tensile strength equivalent to steel. Some regions of the microfibrils are highly crystalline while others are more “amorphous”.

COMMON FEATURES OF BIOLOGICAL MEMBRANES

Membranes are sheetlike, just a few molecules thick and form closed boundaries between cell compartments.

Membranes contain lipids and proteins, with small amounts of carbohydrayes linked to the lipids and proteins.

Lipids in membranes are small with hydrophobic and hydrophilic portions. Lipid bilayers provide a barrier to the diffusion of polar molecules.

Characteristic functions of membranes are mediated by specific proteins, serving as pumps, channels, receptors, energy transducers and enzymes.

Membrane components associate through noncovalent interactions.

Membranes are asymmetrical, with two sides of the membrane differing from each other.

Lipid and protein molecules often diffuse rapidly in the plane of the membrane.

Central transport of ions and molecules into and out of the cell.

Generate proton gradients for ATP production by oxidative phosphorylation.

Receptors bind extracellular signals and transduce the signal to cell interior.

ALL MOLECULES MOVE CONTINUOUSLY BY SIMPLE DIFFUSION

Heat energy causes molecules to move randomly (sometimes called Brownian motion)

If the concentration of molecules is different in 2 regions (this produces a concentration gradient), diffusion will cause molecules to move from a region of high concentration to one of low concentration

The higher the concentration gradient the more rapid the net diffusion

Diffusion evens out the concentrations so they are equal everywhere (maximum entropy)

If 2 different substances have the same concentration gradient, usually one will move faster than the other

Differences in speed between molecules with the same concentration gradient are given in terms of diffusion constants

A substance with a high diffusion constant moves faster than one with a low diffusion constant

In general, large molecules move slower than small molecules

Diffusion across a membrane is called permeability, and membrane diffusion constants are called permeability constants

Metabolism - sum total of all chemical reactions in living cells

Catabolic reactions - degrade macromolecules and other molecules to release energy

Anabolic reactions - used to synthesize macromolecules for cell growth, repair, and reproduction

Can divide metabolism into 4 groups: carbohydrates, lipids, amino acids, nucleotides.

MOST OF THE ENERGY FOR LIFE COMES FROM SUNLIGHT

Total rate of energy delivery from sun to earth (at the top of the atmosphere) = 175,000 terrawatts

Terrawatt = 10^12 watts

Rate of energy capture by plants from the sun = net primary productivity (NPP) = 100 terrawatts

Only ~ 0.06% of sunlight is captured

Captured in chemical bonds, especially in sugar

Small amounts of energy are available to specialized microorganisms from chemical reactions not linked to sunlight

It is estimated that 99% of the energy used by living cells comes from the sun

Incorporation of sunlight into chemical bonds occurs through the process of photosynthesis

“Invented” by cyanobacteria about 2 billion years ago