Chemistry Questions - Essay Example

Introduction Organic compounds are complex carbon compounds. Since carbon atoms can easily form bonds between them organic compounds have their basis made of carbon chains with various shapes lengths. The common atoms are those of nitrogen, hydrogen and oxygen that are found attached to the atoms of carbon Bloomfield V., Crothers D., Tinico I, (2000).Every atom of carbon has a valence of 4 and this makes the atoms being formed more complex. Because the atoms of carbon can form triple and double bond with other atoms it brings about the possibility of variation in organic compound molecular make up. Every living thing has intricate systems of organic and inorganic compounds. Organic compounds comprise of proteins, nuclei acids, carbohydrates and lipids or fats. In this essay these four organic compounds are discussed as well as DNA replication, Chromosome condensation-separation of sister chromatids, the transcription process in which a primary transcript shortens to form a messenger RNA and the codon. Organic compounds There are several types of natural organic compounds such as hydrocarbons. Hydrocarbons are molecules formed with the combination of carbon and hydrogen. They are insoluble in water and distribute very easily. Organic compounds exist in many classes. Originally they were thought to originate from living organisms alone. However in the 1800s people started creating them from simple inorganic proteins. Many organic compounds have a close association with basic life processes like proteins, carbohydrates, lipids and nucleic acids. Carbohydrates Most of the organisms use carbohydrates as energy sources. To add to this some carbohydrates serve the purpose of structural materials. Carbohydrates are the molecules made of hydrogen, carbon, and oxygen. They bond on a ratio of 2 hydrogen atoms to 1 oxygen atoms. Simple carbohydrates are called monosaccharide when they are made of single molecules and disaccharides if they are made of two molecules. Glucose is the most important monossacharide. It is a carbohydrate that has a molecular formula C6H12O6. Glucose happens to be the primary fuel in the bodies of living things. It dissolves easily in water and is taken to the cells of the body by the fluids in the body for metabolism to form energy. Respiration in the cell begins with glucose and it is produced in photosynthesis as the main product. There are three disaccharides occur in living things. They are sucrose, maltose, and lactose. Maltose is composed of two units of glucose linked with covalent bonds. Sucrose is formed when one monosaccharide is linked to another one called fructose. In the figure below we see how sucrose is synthesized and a molecule of water is produced. This process is known as dehydration. The process of reversal is called hydrolysis which is a process where there is a splitting of the molecule and water molecules added. Lactose is made up of galactose and glucose. Some carbohydrates are very complex and the name given to them is polysaccharides. When so many monosaccharides are linked Polysaccharides are formed. Starches are some of the most common polysaccharides. Starches are made up of thousands or hundreds of glucose units that are linked to each other. Carbohydrates are stored in the form of starch. A big part of the population of the world gets its energy from starches such as corn, wheat, potatoes and rice. Cellulose and glycogen are also important polysaccharides. Glycogen made of thousands of units of glucose but these units have a different pattern of bonding. Glucose is stored in the liver of human beings in the form of glycogen Bloomfield V., Crothers D., Tinico I, (2000).Cellulose is basically used as a structural carbohydrate. It is made of units of glucose as well although it is not possible for these units to be released from each other except in a small number of species. Wood is made of cellulose which occurs in cell walls of plants. Paper and cotton fabric are also products of cellulose. The carbohydrate structure is based on a number of sugars. Three sugar levels exist. The monosaccharide has only one attached sugar link. In disaccharides such as lactose and fructose two sugars are attached while in polysaccharides which are complex structures there are a number of sugars that are linked. The chemical structure of carbohydrates enables them to perform functions such as provision of energy and regulating blood glucose, sparing use of proteins for sake of energy, breaking down fatty acids as well as prevention of ketosis, processes of biological recognition, dietary fiber and flavoring and sweetening. Lipids Lipids are those organic molecules that are made of carbon, oxygen and hydrogen atoms. Hydrogen atoms and oxygen are linked with a ratio that is higher in lipids when compared to carbohydrates. Lipids comprise of waxes, fats and steroids which is the material that makes up most of the hormones. The molecules of fat are made of a molecule of glycerol and two, three or one fatty acid molecule. A molecule of glycerol is made of three hydroxyl groups (-OH). A fatty acid is composed of a long chain of between 4 and 24 carbon atoms with a carboxyl group (-COOH) at its end. Fatty acids in fat can all look a like or be different. They are normally bound to the molecule of glycerol by a process in which water is removed. Some fatty acids have more than one double bond within their molecules. Those fats with such molecules are called unsaturated fats. Other fatty acids do not have double bonds. The fats that have these fatty acids are called saturated fats. In many situations of human health it is recommended that unsaturated fats should be consumed instead of saturated fats. When fats are stored within the cells they normally form clear droplets of oil known as globules since fats cannot dissolve in water. Plants normally store fats within their seeds. Animals store these fats in big clear globules within the cells of their dipose tissues. The fats in the dipose tissue normally have a large amount of energy. Because of this they act as a store for energy to the organism. Enzyme lipase is involved in fats breakdown to form glycerol and fatty acids in the digestive system of humans. Generally the structure of lipids gives us two different fat types known as saturated and unsaturated fats. The extra hydrogen, the carboxyl group and the OH bring about this variation. Both fats have poly and mono. Lipids are significant in the bilayers within cell membranes because many are selectively permeable. Fatty acids Fatty acids are molecules that have a lot of diversity whenever they make up a lipid. The molecules are synthesized through elongation of the chain of an acetyl-CoA primer with the groups methylmalonyl-CoA or malonyl-CoA in the fatty acid synthesis process. They are formed of a hydrocarbon chain terminating with a carboxylic acid group. This type of arrangement gives the molecule with a polar hydrophilic end and a water insoluble non polar hydrophilic end. The structure of the fatty acids is among the most important biological lipid categories and is normally used as the building block for lipids with a more complex structure. The carbon chain which has a length of between 4 and 24 carbons can be unsaturated or saturated and could be attached to functional groups that have nitrogen, halogens, sulphur and oxygen. Where there is a double bond it is possible to have a cis or isomerism of a transgeometric nature affecting the molecular configuration of the molecule. Cis- double bonds cause the bending of the fatty acid chain. This effect increases with the rising number of double bonds within the chain. This then plays a cell membrane function and structure. Most fatty acids that occur in nature have the cis configuration the form of trans exists not in certain natural as well as partly hydrogenated oils and fats. Eicosanoids obtained from eicosapentanoic acid and arachidonic acid that include leukotriens, prostaglandins and thromboxanes are good examples of fatty acids with biological importance. Docosahexenoic acid has significance in biological systems as well especially when it comes to sight. Fatty amides and fatty esters are the other main classes of lipids in the category of fatty acids. Included in fatty esters are biochemical intermediaries like wax esters, derivatives of fatty acid thioester coenzyme A, derivatives of fatty acid thioester ACP and fatty acid carnitines. Glycerolipids Glycerolipids are majorly made of mono-, di, and tri-substituted glycerols of which the most well known are the glycerol fatty acid trimesters known as triglycerides. The term triacylglycerol is at certain times used synonymously with triglyceride. These compounds however do not have any hydroxyl group and this is therefore misleading. These compounds have three hydroxyl groups of hydroxyl each of which is esterified by different fatty acids. Since they act as a store of energy these lipids form the biggest store of fat in the tissues of animals. Hydrolysis of glyceride esterbonds and the release of fatty acids and glycerol from dipose tissues are the first steps in fat metabolysis. More glycerolipid subclasses are represented by glycosylglycerols that may have one or many residues of sugar attached to glycerol through a glycosidic linkage. Digalactosyldiacylglycerols occurring in the membranes of plants and the seminolipid from the sperm cells of mammals are the some of the structures falling within this category. Glycerophospholipids Glycerophospholipids also called phospholipids are many in nature and are important components of the lipid double layer in cells and also play a role in cell signaling and metabolism. Neural tissue the brain included has high quantities of glycerophospholipids and when their composition is altered many neurological disorders arise. Glycerophospholipids can be broken into separate classes. Phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine are some of the glycerophospholipids that occur in biological membranes. Sphingolipids Sphingolipids is a family of compounds that is complicated and shares a structural feature which is a sphingoid base backbone which is made from serine and a fatty acyl CoA before being converted into phosphosphingolipids, glycosphingolipids, ceramides and other compounds. The main sphingoid base in mammals is called a sphingosine. Ceramides are a significant subclass of derivatives of the sphingoid base that has an amide linked fatty acid. The fatty acids are saturated or mono-unsaturated and have lengths of chains between 16 and 26 atoms. Sphingomyelins especially ceramide phosphocholines are the main phosphosphingolipids in mammals while insects have ceramide phosphoethanolamines with fungi having phytoceramide phosphoinositols and head groups that contain mannose. Glycosphingolipids are a family of molecules that is diverse having one or many residues of sugar with a glycosidic bond linking the sugar residues to the sphingoid base. Examples are the complex and simple glycosphingolipids like gangliosides and cerebrosides. Sterol lipids Sterol lipids like cholesterol with its derivatives form a very critical component of lipids in the membranes together with sphingomyelins and glycerophospholipids. The steroids which all come from the same fused structure with a four ring core have various biological roles as signaling molecules and hormones. The eighteen carbon steroids (C18) are inclusive of estrogen family while the C19 steroids are made of the androgens like androsterone and testosterone. Mineralocorticoids, glucocorticoids and progestogens are found in the C21 sub class. The costeroids have many vitamin D forms and can be identified with the cleavage of the B ring of the structure of the core. Bile acids and the conjugates are also sterols and in mammals they are oxidized cholesterol derivatives formed in the liver. Phytosterols are the equivalents in plants and examples of these are stigmasterol, β-sitosterol and brassicasterol. Prenol lipids Prenol lipids are made from dimethylallyl diphosphat and isopentenyl diphosphate produced through the path of mevalonic acid (MVA). Simple isoprenoids such as diphosphates and linera alcohols are made when C5 units are successively added and classified based on the amount of the terpene units. Those structures that have more than 40 carbons are called polyterpenes. Carotenoids are significant simple isoprenoids functioning as antioxidants as well as vitamin A precursors. Saccharolipids Saccharolipids are those compounds whose fatty acids are linked to a sugar back bone in a direct manner to form structures compatible with bilayers in memberanes. In saccharolipids the monosaccharide is used to substitute to glycerol backbone found in glycerophospholipids and glycerolipids. Common saccharolipids are the precursors Lipid A component glucosamine in Gram negative bacteria. Common molecules of lipid A are the glucosamine disaccharides that are derivatized with up to seven chains of fatty-acyl. Proteins Proteins are some of the most complex organic compounds and they are made up of amino acids that have hydrogen, carbon, nitrogen and oxygen atoms in them. Some amino acids contain atoms of sulfur, phosphorus and copper or iron which are trace elements. Many proteins have big sizes and are very complex. Nevertheless all proteins have long chains with amino acids that are relatively simple. Twenty different kinds of amino acids exist in nature. Every amino acid contains a carboxyl group (—COOH), an amino group (—NH2) and a groups made of atoms known as an –R group. Amino acids include valine, alanine, histidine, tyrosine, tryptophan and glutamic acid. Amino acids are linked to form proteins through the removal of a water molecule. This process is known as dehydration synthesis and water happens to be the by product of this synthesis. Peptide bonds are the links that from between these amino acids. Small proteins are known as peptides. All living things rely on proteins for existence. Living things are constructed from the proteins. Some proteins are either dissolved or remain as suspensions in the watery substance within the cells while the others are incorporated in different cell structures. Proteins also serve as strengthening and supporting materials in the tissues outside of the cells. Cartilage, bone, ligaments and tendons are all made of protein. Proteins are important in constructing enzymes. Enzymes serve the purpose of catalyzing chemical reactions taking place in the cells. They don’t get used up in the reaction but they remain available as catalysts in succeeding reactions. Every species makes proteins that are different from those manufactured in other species. The information used in the synthesis of unique proteins is found in the cell nucleus. The genetic code is the one that specifies the sequence of amino acids in proteins. It therefore acts as the regulator of the chemistry that occurs in the cell. Proteins can also act as a reserve for energy in the cell. If the amino group is extracted from an amino acid the compound that remains is rich in energy. Many proteins are made of linear polymers built of over 20 different L-α-amino acids. All proteinogenic amino acids have similar structural features among them a α-carbon on which there is bonded the carboxyl group, amino group and a variable side chain. It is proline alone that is different from this kind of structure because it has an unusual ring on the N-end of the amine group which drives the CO-NH amide moiety into a conformation that is fixed. The standard amino acid side chains have a big variety of properties and chemical structures. The total effect of all the side chains of an amino acid in a protein is the one that determines the chemical activity and the three dimensional structure of that protein. Peptide bonds link the amino acids within a polypeptide chain. When linked in a protein chain the amino acid is known as a residue while the linked series of nitrogen, oxygen and carbon atoms are called the backbone or main chain. The peptide bond possesses two forms of resonance that contribute to the character of the double bond and also prevent rotation on its axis making the alpha atoms roughly coplanar. The two other dihedral angles within the peptide bond dictate the shape taken by the protein backbone. The end of the protein whose carboxyl group is free is called the carboxy terminus or C-terminus while the end that has a free amino group is called the amino terminus or N-terminus. The terms peptide, polypeptide and protein tend to be a bit ambiguous and their meaning overlap. Protein I used on a full biological molecule that is stable. Peptide refers to a short amino acid oligomers that does not have the three dimensional structure that is stable. The structure of proteins exists in primary secondary, tertiary and quaternary levels. The primary structure refers to the sequence taken by the amino acids in the chain. Secondary structure has to do with how the protein molecule is shaped based on the hydrogen bond between the groups –C=O and –N-H. the tertiary structure relies on the interaction existing between R groups resulting in bending and folding. Finally the quaternary structure results from the protein subunits interacting resulting in the categorization of the protein as fibrous, conjugated or globular. Nucleic acids These are biological molecules that are very important in life including deoxyribonucleic acid (DNA). Nucleic acids and the proteins make up the most vital macromolecules and each of them occurs abundantly in living things in which they encode, transmit and express generic information. Nucleic acids are big molecules just like the proteins. Nucleic acids are made od other smaller units known as nucleotides. Each of these nucleotides has a molecule of carbohydrates, a phosphate group and a molecule containing nitrogen that is a nitrogenous base owing to its properties. Living organisms possess two vital nucleic acids one of them being the ribonucleic acid (RNA) and deoxyribonucleic acids (DNA). DNA occurs within the cell nucleus with RNA occurring in both the cytoplasm and the nucleus. The components of both the RNA and DNA bring out their differences. RNA contains a ribose while DNA has a carbohydrate deoxyribose. To add to this DNA has a base thymine with RNA having a uracil. Occurrence and nomenclature The word nucleic acid is used to refer to both RNA and DNA which are members of a biopolymers family. The name is also synonymous with polynucleotide. Nucleic acids got their name from their discovery in the nucleus and also for the existence of phosphate groups. Although they were initially discovered inside the nucleus of eukaryotic cells the nucleic acids currently occur in all forms of life even in archaea, bacteria, chloroplasts, mitochondria, viroids and viruses. All living organelles and cells have both RNA and DNA but viruses have either RNA or DNA and not both. The nucleotide is the primary component in biological nucleic acids. Each nucleotide has a pentose sugar which is either a ribose or deoxyribose, a nucleobase and a phosphate group. Nucleic acids can be created within the laboratory by use of enzymes called DNA and RNA polymerases as well as through solid phase chemical synthesis. The chemical methods make it possible for altered nucleic acids not present in nature to be generated. An example is peptide nucleic acids. Molecular composition and size Nuclei acids have various sizes but generally they are normally big molecules. DNA molecules have been found to be the biggest individual molecules in existence. Biological nucleic acid molecules that have been studied well have sizes ranging from 21 nucleotides in small interfering RNA to big chromosomes such as the human chromosome 1 that has 247 million base pairs. DNA molecules that occur naturally in most of the cases have double strands while the RNA molecules have single strands. Exceptions to these are many although certain viruses possess genomes comprising of double stranded RNA. Other viruses DNA genomes with single strands and in certain cases there can be formed structures of nucleic acids that have 3 to 4 strands. Nuclei acids are basically linear polymer chains of nucleotides. Every nucleotide is made of 3 components which are a pyrimidine nucleobase or purine, a phosphate group and a pentose sugar. The substructure that has a sugar and nucleobase is called a nucleoside. The different types of nucleic acids differ based on the structure of sugar within their nucleotides. DNA has 2- deoxyribose, RNA has a ribose with the only difference being the hydroxyl group. The nucleobases inside the two types of nucleic acids are different. Cytosine, adesine and guanine occur in DNA and RNA while thymine is found in DNA and uracil in RNA. The phosphates and sugars within the nucleic acids are linked to one another in a sugar phosphate backbone chain that is alternating via phosphodiester linkages. Within conventional nomenclature phosphate groups are attached to the 5-end and 3-end sugar carbons. This allows the nuclei acids to have directionality with the end of the molecules of nucleic acids are called 5 end and 3 end. Nucleobases are linked to sugars through N-glycosidic linkage that has 1 carbon pentose sugar ring and a nucleobase ring nitrogen N-9 for purines and N-1 for pyrimidines. Nucleosides that are not to standard occur in both DNA and RNA and normally form from the standard nucleosides in the DNA molecule being modified. Transfer RNA molecules have a big amount of modified nucleosides. Deoxyribonucleic acid This is a nucleic acid that has the genetic instructions being utilized in functioning and development of every living thing. DNA molecules have a major role of storing information for a long time and the DNA is normally compared to a number of blue prints because it carries the instructions necessary for the construction of other cell components like RNA and protein molecules Gupta R. Kumar M. & Jain M. (2007).Those segments of the DNA that hold this information are known as genes. Other sequences of DNA perform structural purposes or can be used to regulate how the genetic information is being used. Ribonucleic acid Ribonucleic acid (RNA) does the work of changing genetic information from the genes to sequences of amino acids in proteins. There are three universal types of RNA known as ribosomal RNA, transfer RNA, and messenger RNA. Messenger RNA serves the purpose of carrying genetic sequence information from the DNA to ribosomes and back and in the process it directs the synthesis of proteins. Ribosomal RNA is a main ribosome component as it acts as a catalyst in the formation of peptide bonds. Transfer RNA carries amino acids for use in synthesizing proteins and also decodes mRNA. To add to this there are many other RNA classes that are known. Characteristics of organic compounds Calories arise from three major varieties which are proteins, lipids or fats and carbohydrates. They also provide energy since they are macronutrients. Carbohydrates and proteins provide 4 calories each with lipids and fats providing 9 calories for every gram. Each of these micronutrients has its own characteristics which make it suitable for certain functions in the body. Carbohydrates These are the molecules that are so abundant in nature and the diet of an average person is composed of a lot of carbohydrates which have many other functions apart from provision of energy. They also act as storage for energy in the form of glycogen present in the liver. Classification of carbohydrates is done on the basis of their structure. Simple sugars or monosaccharides include fructose and glucose. Disaccharides include sucrose and lactose. Complex carbohydrates or the starches are built from simple sugars that are strung together to from bigger molecules. Lipids/fats Dietary fats otherwise called lipids are a source of energy that is concentrated. They assist the body in digesting vitamins soluble in fats like vitamins A, D and E. In addition it is possible for lipids to be converted into substances like prostaglandins that modulate inflammatory and pain responses. Hormones such as estrogen and testosterone are obtained from lipids whose classification is based on their fatty acid structure. Saturated fatty acids do not have any double bonds. These fats occur in animal products such as cholesterol. Unsaturated fatty acids occur in vegetable oils. Trans fats is a synthetic lipid present in vegetable shortening and margarine. Protein Protein has nitrogen and this makes it unique of all macronutrients. Carbohydrates and lipids are composed of hydrogen, carbon and oxygen atoms. Nitrogen becomes an essential nutrient because it has nitrogen in it. The body converts proteins into carbohydrates or fats but since the macronutrients have no nitrogen it is not possible for the reverse to happen and therefore protein is necessary in diet. Proteins are composed of 20 amino acids combined differently. Protein is necessary for body repair and growth and the maintenance of the muscles. Since it is also an enzyme it helps in powering the chemical reactions within the body. DNA replication DNA replication takes place in the S stage during interphase. Interphase comes between two meiotic or mitotic divisions. It may be divided into 3 stages which are G1, S, and G2. During Gap 1 the cell are growing and building up ATP to prepare for the replication of DNA. In stage S or synthesis there is replication of DNA. In the G2 stage there is preparation for the cell for cell division in meiosis or mitosis. Replication of DNA takes place in all living organisms and the DNA is copied to bring about biological inheritance. The process is initiated when a DNA molecule with double strands brings forth two copies of the molecule that are identical. Chromosome condensation-separation of sister chromatids Condensation of chromosomes and the separation of sister chromatids occurs during the anaphase stage. Anaphase occurs in either mitosis or meiosis where chromosomes shift to the cells’ opposite poles. Roughly one percent of the duration of the cell cycle is accounted for through anaphase. It starts when the metaphase – anaphase transition is triggered in a regulated manner. The end of metaphase is marked by cyclin being destroyed and this is necessary for kinases dependent on metaphase cyclin to function. Securin cleavage marks the beginning of anaphase. Securin is a protein with the ability to inhibit a protease called separase. Separase goes on to cleave cohesion which is the protein that hold together the sister chromatids. In the anaphase stage there is the splitting and separation of chromosomes before they move to opposite poles within the cell. When the chromosomes are moving to the cells’ opposite sides the non keticore spindle fibers make a ratcheting action in which they push each other and stretch the cell to form an oval. With the completion of anaphase the cell enters into telophase. Transcription In the transcription process a copy of the RNA is made from a single gene. Genes are particular regions in a chromosome DNA. RNA polymerase is the enzyme that is used in the process of transcription. RNA polymerase exists in many forms. Transcription of many of the genes in eukaryotes is done by RNA polymerase 2. The new RNA is made form four ribonucleoside triphosphates namely GTP, CTP, ATP and UTP. It is that ATP used in energy production within the cell. Similar to replication of DNA transcription goes on 5- to 3’ where new bases add to the free 3’ OH group. As opposed to replication there is no need for building a primer in transcription. Transcription begins instead at the DNA region called promoter. For genres that code proteins the promoter is found at a few bases 5’ to the first transcribed base upstream. Promoter sequences resemble each other although they are not identical. A consensus sequence is obtained when a number of promoters are compared. All promoters resemble this sequence but are not the same. Process of transcription The process of transcription begins when the RNA polymerase binds to the promoter. The binding takes place only though certain conditions whenever the gene is “on” Many other proteins which are the transcription factors assist the RNA polymerase to bind to the promoter. There are other DNA sequences on the upper side of the promoter also take part. When bound to the promoter the RNA polymerase must unwind a tiny DNA section to be used as the template for synthesis of an RNA copy of DNA. The coding strand is the strand of DNA that serves as a template. The non coding strand is the other strand. The RNA comes from 5’ end to 3’ end and the reading of the coding strand is done from 3’ to 5’. RNA polymerase continues down on the RNA as it synthesizes the copy of RNA. In prokaryotes the end of every RNA is at a particular terminator sequence. In eukaryotes there is no particular end point to transcription. In the processing of RNA the RNA gets a definitive point of termination. In prokaryotes the messenger RNA is the RNA copy of a gene that is converted into a protein. Translation begins before the end of transcription. In eukaryotes before translation begins, a gene’s primary RNA transcript must be processed further. The step is known as RNA processing. It must also be taken out of the nucleus to the cytoplasm Van Holde KE, Mathews CK (1996).RNA processing involves adding acap to the 5’ end, adding a poly-A tail to the 3’ end and splicing out introns. RNA is unstable on its ends and the ends go through modification to give it protection. Codon The term codon refers to a set with three nucleotides adjacent to one another otherwise known as triplet. In mRNAit is the base pair that has corresponding aniticodon of tRNA molecule which carries a specific a mino acid and thus specifying the sequence and type of the amino acids for synthesis of proteins. In a codon there are 3 adjacent nucleotides that make up the genetic code which determines how a specific amino acid will be inserted into a polypeptide. Conclusion The essay has examined the four classes of organic compounds namely carbohydrates, lipids, proteins and nucleic acids which are very essential in the cells of living things. It also features the replication of DNA and chromosome condensation and separation of sister chromatids as well as the transcription process and codon. The four classes of organic compounds are different in structure and perform different functions in living cells. They also have different distinct characteristics that differentiate them from other groups. Different characteristics also exist between sub groups in the same class of organic compounds. The chemical structures of these compounds enable them to perform their functions effectively. The processes described in the paper as taking place within the cell are important for the continued survival of living cells and by extension living things. Bibliography Bloomfield V., Crothers D., Tinico I, (2000) Nucleic acids: structures, properties and functions, University science books Branden C, Tooze J (1999). Introduction to Protein Structure. New York: Garland Pub.  Enger D.E, Ross F. C, Bailey D. B., (2009) Concepts in biology, McGraw Hill Finch P. (1999) Crabohydrates: Structures, synthesis and dynamics, Springer Gupta R. Kumar M. & Jain M. (2007) Organic Compounds, Springer Johnson R. L. (2005) Genetics, Twenty First Century Books Morgan, David L. (2007). The cell cycle: principles of control. London: Published by New Science Press in association with Oxford University Press. Murray RF, Harper HW, Granner DK, Mayes PA, Rodwell VW (2006). Harper's Illustrated Biochemistry. New York: Lange Medical Books/McGraw-Hill.  Stumpf K. P., Conn E. (1987) Lipids: Structure and function, Academic press Van Holde KE, Mathews CK (1996). Biochemistry. Menlo Park, California: Benjamin/Cummings Pub. Co., Inc. Read More

The carbohydrate structure is based on a number of sugars. Three sugar levels exist. The monosaccharide has only one attached sugar link. In disaccharides such as lactose and fructose two sugars are attached while in polysaccharides which are complex structures there are a number of sugars that are linked. The chemical structure of carbohydrates enables them to perform functions such as provision of energy and regulating blood glucose, sparing use of proteins for sake of energy, breaking down fatty acids as well as prevention of ketosis, processes of biological recognition, dietary fiber and flavoring and sweetening.

Lipids Lipids are those organic molecules that are made of carbon, oxygen and hydrogen atoms. Hydrogen atoms and oxygen are linked with a ratio that is higher in lipids when compared to carbohydrates. Lipids comprise of waxes, fats and steroids which is the material that makes up most of the hormones. The molecules of fat are made of a molecule of glycerol and two, three or one fatty acid molecule. A molecule of glycerol is made of three hydroxyl groups (-OH). A fatty acid is composed of a long chain of between 4 and 24 carbon atoms with a carboxyl group (-COOH) at its end.

Fatty acids in fat can all look a like or be different. They are normally bound to the molecule of glycerol by a process in which water is removed. Some fatty acids have more than one double bond within their molecules. Those fats with such molecules are called unsaturated fats. Other fatty acids do not have double bonds. The fats that have these fatty acids are called saturated fats. In many situations of human health it is recommended that unsaturated fats should be consumed instead of saturated fats.

When fats are stored within the cells they normally form clear droplets of oil known as globules since fats cannot dissolve in water. Plants normally store fats within their seeds. Animals store these fats in big clear globules within the cells of their dipose tissues. The fats in the dipose tissue normally have a large amount of energy. Because of this they act as a store for energy to the organism. Enzyme lipase is involved in fats breakdown to form glycerol and fatty acids in the digestive system of humans.

Generally the structure of lipids gives us two different fat types known as saturated and unsaturated fats. The extra hydrogen, the carboxyl group and the OH bring about this variation. Both fats have poly and mono. Lipids are significant in the bilayers within cell membranes because many are selectively permeable. Fatty acids Fatty acids are molecules that have a lot of diversity whenever they make up a lipid. The molecules are synthesized through elongation of the chain of an acetyl-CoA primer with the groups methylmalonyl-CoA or malonyl-CoA in the fatty acid synthesis process.

They are formed of a hydrocarbon chain terminating with a carboxylic acid group. This type of arrangement gives the molecule with a polar hydrophilic end and a water insoluble non polar hydrophilic end. The structure of the fatty acids is among the most important biological lipid categories and is normally used as the building block for lipids with a more complex structure. The carbon chain which has a length of between 4 and 24 carbons can be unsaturated or saturated and could be attached to functional groups that have nitrogen, halogens, sulphur and oxygen.

Where there is a double bond it is possible to have a cis or isomerism of a transgeometric nature affecting the molecular configuration of the molecule. Cis- double bonds cause the bending of the fatty acid chain. This effect increases with the rising number of double bonds within the chain. This then plays a cell membrane function and structure. Most fatty acids that occur in nature have the cis configuration the form of trans exists not in certain natural as well as partly hydrogenated oils and fats.

Eicosanoids obtained from eicosapentanoic acid and arachidonic acid that include leukotriens, prostaglandins and thromboxanes are good examples of fatty acids with biological importance.

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