Major bio molecule

Four major bio molecule classes

Carbohydrates (saccharides) - Molecules consist of carbon, hydrogen and oxygen atoms. A major food source and a key form of energy for most organisms. When combined together to form polymers, carbohydrates can function as long term food storage molecules, as protective membranes for organisms and cells, and as the main structural support for plants and constituents of many cells and their contents.

Lipids (fats) - Molecules consist of carbon, hydrogen, and oxygen atoms. The main constituents of all membranes in all cells (cell walls), food storage molecules, intermediaries in signaling pathways, Vitamins A, D, E and K, cholesterol.

Proteins - Molecules contain nitrogen, carbon, hydrogen and oxygen. They act as biological catalysts (enzymes), form structural parts of organisms, participate in cell signal and recognition factors, and act as molecules of immunity. Proteins can also be a source of fuel.

Nucleic acids (nucleotides) - DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). These molecules are involved in genetic information, as well as forming structure within cells. They are involved in the storage of all heritable information of all organisms, as well as the conversion of this data into proteins.

Most organic matter on earth is made up of carbohydrates¹ because they are involved in so many aspects of life, including:

Carbohydrates

Bread, pasta, beans, potatoes, bran, rice and cereals are carbohydrate-rich foods. Most carbohydrate rich foods have a high starch content. Proteins and fats require more water for digestion than carbohydrates.Carbohydrates are the most common source of energy for most organisms and animals, including humans.

What is carbohydrates?what is Glucose

There are four major classes of biomolecules - carbohydrates, proteins, nucleotides, and lipids. Carbohydrates, or saccharides, are the most abundant of the four.

Carbohydrates have several roles in living organisms, including energy transportation, as well as being structural components of plants and arthropods.

Carbohydrate derivates are actively involved in fertilization, immune systems, the development of disease, blood clotting and development.

They are called carbohydrates because the carbon, oxygen and hydrogen they contain are generally in proportion to form water with the general formula C_n (H₂O)_n. 

Contents of this article:

1. Four major biomolecule classes                           
   
2. What are saccharides?
3. Types of polysaccharides
4. Carbohydrates and nutrition
5. High-carb vs. low-carb
6. Blood sugar levels
7. The glycemic index

• Energy stores, fuels, and metabolic intermediaries.
• Ribose and deoxyribose sugars are part of the structural framework of RNA and DNA.
• The cell walls of bacteria are mainly made up of polysaccharides (types of carbohydrate).
• Cellulose (a type of carbohydrate) makes up most of plant cell walls.
• Carbohydrates are linked to many proteins and lipids (fats), where they are vitally involved in cell interactions.

What are saccharides?

1. Saccharides, or carbohydrates, are sugars or starches. Saccharides consist of two basic compounds: aldehydes (composed of double-bonded carbon and oxygen atoms, plus a hydrogen atom), and keytones (composed of double-bonded carbon and oxygen atoms, plus two additional carbon atoms).
   There are various types of saccharides, including monosaccharides, disaccharides, and polysaccharides.     

   Monosaccharides

   This is the smallest possible sugar unit. Examples include glucose, galactose or fructose. When we talk about blood sugar we are referring to glucose in the blood; glucose is a major source of energy for a cell.² In human nutrition, galactose can be found most readily in milk and dairy products, while fructose is found mostly in vegetables and fruit.
   When monosaccharides merge together in linked groups they are known as polysaccharides.

   Disaccharides

   Two monosaccharide molecules bonded together. Disaccharides are polysaccharides - "poly..." specifies any number higher than one, while "di..." specifies exactly two. Examples of disaccharides include lactose, maltose, and sucrose. If you bond one glucose molecule with a fructose molecule you get a sucrose molecule.
   Sucrose is found in table sugar, and is often formed as a result of photosynthesis (sunlight absorbed by chlorophyll reacting with other compounds in plants). If you bond one glucose molecule with a galactose molecule you get lactose, which is commonly found in milk.

   Polysaccharides

   A chain of two or more monosaccharides. The chain may be branched (molecule is like a tree with branches and twigs) or unbranched (molecule is a straight line with no twigs). Polysaccharide molecule chains may be made up of hundreds or thousands of monosaccharides.
   Polysaccharides are polymers. A simple compound is a monomer, while a complex compound is a polymer which is made of two or more monomers. In biology, when we talk about building blocks, we are usually talking aboutmonomers.

   Types of polysaccharides

   Polysaccharides may act as food stores in plants in the form of starch, or food stores in humans and other animals in the form of glycogen. Polysaccharides also have structural roles in the plant cell wall in the form of cellulose or pectin, and the tough outer skeleton of insects in the form of chitin.

   Storage polysaccharides

   Glycogen
   A polysaccharide that humans and animals store in the liver and muscles.
   Starch
   These are glucose polymers made up of Amylose and Amylopectin. Amylose molecule chains are linear (long but no branches) while Amylopectin molecules are long and branch out - some Amylopectin molecules are made of several thousand glucose units.
   Starches are not water soluble. Humans and animals digest them by hydrolysis - our bodies have amylases which break them down. Rich sources of starches for humans include potatoes, rice and wheat.

   Structural polysaccharides

   Cellulose
   The structural constituents of plants are made mainly from cellulose - a type of polysaccharide. Wood is mostly made of cellulose, while paper and cotton are almost pure cellulose. Lignin, derived from wood, is a key component in the secondary walls of plant cells. Some animals, such as termites, can digest cellulose because their gut has a type of bacteria that has an enzyme which breaks down cellulose - humans cannot digest cellulose.
   Chitin
   Chitin, a polysaccharide, is one of the most abundant natural materials in the world. Microorganisms, such as bacteria and fungi secrete chitinases, which over time can break down chitin. These microorganisms also have receptors to the simple sugars that result from this breakdown (decomposition). The bacteria and fungi convert the decomposed chitin into simple sugars and ammonia.
   Chitin is the main component of fungi cell walls, the exoskeletons (hard outer shell/skin) of arthropods, such as crabs, lobsters, ants, beetles, and butterflies. Chitin is also the main component of the beaks of squid and octopuses. Chitin is useful for several industrial and medical purposes.
   Bacterial polysaccharides
   These are polysaccharides that are found in bacteria, especially in bacterial capsules. Pathogenic (illness causing) bacteria often produce a thick layer of mucous-like polysaccharide which cloaks the bacteria from the host's immune system. In other words, if the bacteria were in a human, that human's immune system would less likely attack the bacteria because the polysaccharide layer masks its pathogenic properties. E. coli, which can sometimes cause disease, produces hundreds of different polysaccharides.

What is the Protein?

Proteins are large biological molecules, or macro molecules, consisting of one or more long chains of amino acid residues A large molecule composed of one or more chains of amino acids in a specific order; the order is determined by the base sequence of nucleotides in the gene that codes for the protein. Proteins are required for the structure, function, and regulation of the body's cells, tissues, and organs; and each protein has unique functions. Examples are hormones, enzymes, and antibodies.

Proteins are essential nutrients for the human body. They are one of the building blocks of body tissue, and can also serve as a fuel source. As a fuel, proteins contain 4 kcal per gram, just like carbohydrates and unlike lipids, which contain 9 kcal per gram. The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition.

Proteins are polymer chains made of amino acids linked together by peptide bonds. During human digestion, proteins are broken down in the stomach to smaller polypeptide chains via hydrochloric acid and protease actions. This is crucial for the synthesis of the essential amino acids that cannot be biosynthesized by the body.

There are nine essential amino acids which humans must obtain from their diet in order to prevent protein-energy malnutrition. They are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine.There are five dispensable amino acids which humans are able to synthesize in the body. These five are alanine, aspartic acid, asparagine, glutamic acid and serine. There are six conditionally essential amino acids whose synthesis can be limited under special pathophysiological conditions, such as prematurity in the infant or individuals in severe catabolic distress. These six are arginine, cysteine, glycine, glutamine, proline and tyrosine

Humans need the essential amino acids in certain ratios. Some protein sources contain amino acids in a more or less'complete' sense. This has given rise to various ranking systems for protein sources, as described in the article.

Animal sources of protein include meats, dairy products, fish and eggs. Vegan sources of protein include whole grains, pulses, legumes, soy, and nuts. Vegetarians and vegans get "enough" essential amino acids by eating a variety of plant proteins. It is commonly believed that athletes should consume a higher-than-normal protein intake to maintain optimal physical performance.

Protein function in the body

Protein is a nutrient needed by the human body for growth and maintenance. Aside from water, proteins are the most abundant kind of molecules in the body. Protein can be found in all cells of the body and is the major structural component of all cells in the body, especially muscle. This also includes body organs, hair and skin. Proteins are also used in membranes, such as glycoproteins. When broken down into amino acids, they are used as precursors to nucleic acid, co-enzymes, hormones, immune response, cellular repair, and other molecules essential for life.Additionally, protein is needed to form blood cells.

Amino Acid

1. a simple organic compound containing both a carboxyl (—COOH) and an amino (—NH₂) group.

   "the amino-acid sequence of a protein"
2. 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- (α-), beta- (β-), gamma- (γ-) or delta- (δ-) amino acids; other categories relate to polarity, pH level, and side-chain group type (aliphatic, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form ofproteins, amino acids comprise the second-largest component (water is the largest) of human muscles, cells and othertissues. Outside proteins, amino acids perform critical roles in processes such as neurotransmitter transport andbiosynthesis.
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   In biochemistry, amino acids having both the amine and the carboxylic acid groups attached to the first (alpha-) carbon atom have particular importance. They are known as 2-, alpha-, or α-amino acids (genericformula H₂NCHRCOOH in most caseswhere 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 23 proteinogenic ("protein-building") amino acids,which combine intopeptide 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 three ("non-standard" or "non-canonical") are selenocysteine (present in many noneukaryotes as well as most eukaryotes, but not coded directly by DNA), pyrrolysine (found only in some archea and one bacterium) and N-formylmethionine (which is often the initial amino acid of proteins in bacteria, mitochondria, and chloroplasts). 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.

   
   

   Many important proteinogenic and non-proteinogenic amino acids also play critical non-protein roles within the body. For example, in the human brain, glutamate (standardglutamic acid) and gamma-amino-butyric acid ("GABA", non-standard gamma-amino acid) are, respectively, the main excitatory and inhibitory neurotransmitters;hydroxyproline (a major component of the connective tissue collagen) is synthesised from proline; the standard amino acid glycine is used to synthesise porphyrins used inred blood cells; and the non-standard carnitine is used in lipid transport.

   
   

   Nine proteinogenic amino acids are called "essential" for humans because they cannot be created from other compounds by the human body and, so, must be taken in as food. Others may be conditionally essential for certain ages or medical conditions. Essential amino acids may also differ between species.

   
   

   Because of their biological significance, amino acids are important in nutrition and are commonly used in nutritional supplements, fertilizers, and food technology. Industrial uses include the production of drugs, biodegradable plastics, and chiral catalysts.
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Lipids

1. 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.

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   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, signaling, and acting as structural components of cell membranes.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, multilamellar/unilamellar 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 isoprene 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 othersterol-containing metabolites such as cholesterol. 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.

1. Fatty acids

   Fatty acids or fatty acid residues when they form part of a lipid, are a diverse group of molecules synthesized by chain-elongation of an acetyl-CoA primer withmalonyl-CoA or methylmalonyl-CoA groups in a process called fatty acid synthesis. They are made of a hydrocarbon chain that terminates with a carboxylic acid group; this arrangement confers the molecule with a polar, hydrophilic end, and a nonpolar, hydrophobic end that is insoluble in water. The fatty acid structure is one of the most fundamental categories of biological lipids, and is commonly used as a building-block of more structurally complex lipids. The carbon chain, typically between four and 24 carbons long, may be saturated or unsaturated, and may be attached to functional groups containing oxygen, halogens, nitrogen, and sulfur. If a fatty acid contains a double bond, there is the possibility of either a cis or trans geometric isomerism, which significantly affects the molecule'sconfiguration. Cis-double bonds cause the fatty acid chain to bend, an effect that is compounded with more double bonds in the chain. Three double bonds in 18-carbon linolenic acid, the most abundant fatty-acyl chains of plant thylakoid membranes, render these membranes highly fluid despite environmental low-temperatures,and also makes linolenic acid give dominating sharp peaks in high resolution 13-C NMR spectra of chloroplasts. This in turn plays an important role in the structure and function of cell membranes.Most naturally occurring fatty acids are of the cis configuration, although the trans form does exist in some natural and partially hydrogenated fats and oils.
   

   Examples of biologically important fatty acids include the eicosanoids, derived primarily from arachidonic acid and eicosapentaenoic acid, that includeprostaglandins, leukotrienes, and thromboxanes. Docosahexaenoic acid is also important in biological systems, particularly with respect to sight. Other major lipid classes in the fatty acid category are the fatty esters and fatty amides. Fatty esters include important biochemical intermediates such as wax esters, fatty acid thioester coenzyme A derivatives, fatty acid thioester ACP derivatives and fatty acid carnitines. The fatty amides include N-acyl ethanolamines, such as thecannabinoid neurotransmitter anandamide.

   Glycerolipids

   Glycerolipids are composed of mono-, di-, and tri-substituted glycerols, the best-known being the fatty acid triesters of glycerol, called triglycerides. The word "triacylglycerol" is sometimes used synonymously with "triglyceride". In these compounds, the three hydroxyl groups of glycerol are each esterified, typically by different fatty acids. Because they function as an energy store, these lipids comprise the bulk of storage fat in animal tissues. The hydrolysis of the ester bonds of triglycerides and the release of glycerol and fatty acids from adipose tissue are the initial steps in metabolising fat.
   Additional subclasses of glycerolipids are represented by glycosylglycerols, which are characterized by the presence of one or more sugar residues attached to glycerol via a glycosidic linkage. Examples of structures in this category are the digalactosyldiacylglycerols found in plant membranes and seminolipid from mammalian sperm cells. 

1. Nucleic Acid

2. 1. Nucleic acids are biopolymers, or large biomolecules, essential for all known forms of life. Nucleic acids, which include DNA(deoxyribonucleic acid) and RNA (ribonucleicacid), are made from monomers known as nucleotides.
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      Nucleic acids are biopolymers, or large biomolecules, essential for all known forms of life. Nucleic acids, which include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are made frommonomers known as nucleotides. Each nucleotide has three components: a 5-carbon sugar, aphosphate group, and a nitrogenous base. If the sugar is deoxyribose, 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 are 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.

      
      

      Nucleic acids were discovered by Friedrich Miescher in 1869.Experimental studies of nucleic acids constitute a major part of modern biological and medical research, and form a foundation for genomeand forensic science, as well as the biotechnology and pharmaceutical industries

The term nucleic acid is the overall name for DNA and RNA, members of a family of biopolymers,and is synonymous withpolynucleotide. 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.