The Purpose Of Haemoglobin Biology Essay

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In carrying oxygen hemoglobin binds the oxygen in its structure as follows and then it is transported through the red blood cells to the needy tissues.

When the hemoglobin is oxygenated is assumes a planar shape while deoxygenated hemoglobin has a non planar shape usually called a domed shape. The oxygenated blood is bright red while the deoxygenated blood is somehow bluish.

Hydrogen and carbon dioxide regulate the release of oxygen in a process called Bohr's effect which is a process named after the person called Christian Bohr who discovered the effect or process. In the process the amino termini and the side chains of the histidine amino acid play an important role in Bohr's effect. This is the case as in dissociation at high Ph the side chains of histidine are not protonated and the salt bridge is not formed and as the Ph drops the salt is formed with the amino acid aspartate due to the protonation of the side chains of histidine. This in turn leads to an increased tendency of the hemoglobin to release oxygen. Carbon dioxide also plays a vital role in the association of oxygen to the hemoglobin as carbon dioxide reacts with the terminal amino group to form negatively charged carbamate and in this case hemoglobin bound with the carbon dioxide are carried to the lungs for oxygenation.The diagram below show how the salt bridge is formed during the dissociation of oxygen and the hemoglobin.

Source Biochemistry Fifth Edition, by Jeremy M. Berg, John L Tymoczco and Lubert Strayer.

Hemoglobin has a tetramer structure which has two subunits namely the alpha and the beta subunits. The alpha sub units are each made up of 144 residues while the beta sub units are 146 residues. This hemoglobin structure is usually called a quaternary structure.. Myoglobin on the other side is a single polypeptide structure made up of 153 amino acid residues. Both Myoglobin and hemoglobin are oxygen binding structures but myoglobin binds more rigidly than hemoglobin. However, Hemoglobin binds four molecules of oxygen while myoglobin only binds one molecule of oxygen.

Myoglobin structure Hemoglobin Structure

Sickle Cell Anemia

Sickle cell anemia is an inherited disorder which affects the red blood cells. In the case of the sickle cell the body makes sickle shaped red blood cells. These cells are abnormal in the sense that they don't move easily in the blood vessels. The diagrams below show structures of both the normal red blood cell and the sickle cell red blood cells.

Source: www.nhlbi.nih.gov/health/dci/Diseases/Sca/SCA

Sickle red blood cells because of their sickle shapes carry less blood to the body tissues. This means that the body tissues get far much less oxygen than the normal red blood cells. The cause of even less supply of oxygen could also be caused by the sickle cells clumping on the walls of the blood vessels thus less oxygen is taken to body tissues.

Sickle cell is a hereditary disease often cause by genetic mutation. In a normal human body, there exist genes found on structures called chromosomes. Each cell of the body normally contains 23 pairs of chromosomes. In this pairs, the 11th pair contains a specific gene for normal production of haemoglobin. An error commonly known as mutation in this particular gene results to sickle celled disease. A person is born with sickle cell disease only if two Hbs genes are inherited from both of parents. On the other hand a person born with only one Hbs gene is healthy and therefore referred to as a carrier of the disease.

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Lipids are heterogenous group of biological compounds that are insoluble in water. Lipids provide energy reserves in the form of triacylglycerols. Triacylglycerols are compounds made of glycerol and 3 fatty acids. Triacylglycerols are hydrolyzed from lipoproteins by an enxyme called lipoprotein lipase to produce glycerol, fatty acids and monoglycerides that enter the adipose cells. The adipose cells store the fat and break it down to provide energy in form of ATP when needed. The triacylglycerols are stored in a dipose tissue and are broken down to provide energy in the form of ATP during starvation.

Saturated fatty acids are fatty acid without carbon-carbon double bonds. The lack of carbon -carbon double bonds make saturated fatty acids to consist of many hydrogen bonds in their structure. The lack of carbon-carbon double bonds gives saturated fatty acids a high melting point due to the energy required to break the strong covalent bonds in its structure. unsaturated fatty acid are fatty acids which contain one or more carbon -carbon double bonds in there structure the presence of the carbon-carbon double bonds in their structure make the unsaturated consist of fewer hydrogen bonds in their structure. This also makes unsaturated fatty acids to have lower melting point and make them to be easily oxidized.

Example of an Unsaturated Fatty Acid

Example of a saturated fatty Acid

Source:

B

Fatty acids are long -chain hydrocarbon containing a carboxylic acid moiety at one end. The chain length ranges from 4 to 30 carbons. According to Glew.RH william they also serve as precussors to longer fatty acid that make eicosanoid which are powerful compounds that participate in the regulation of blood clot formation and immune response. Fatty acids also serve as the components of more complex membrane lipid and as the components of stored fat in the form of triacylglycerols.

A mosaic can be defined as a structure that is made up of many different parts. Similary, the cell membrane is made up of different types of macromolecules.

http://upload.wikimedia.org/wikipedia/commons/thumb/3/3a/Cell_membrane_detailed_diagram_4.svg/400px-Cell_membrane_detailed_diagram_4.svg.png

According cell membrane fluid mosaic model of S. J. Singer and Garth Nicolson 1972, the biological membranes are well thought-out as a two-dimensional liquid in which all the lipid protein molecules diffuse less or more easily. Above picture may only be valid in the space scale of 10 nm.

C.

Fat is considered to be an integral part of a person's healthy diet, even though some of them are - especially the saturated fats - are associated with an elated risk of cardiopulmonary diseases. Incorporating little or even no fats in our meals can be detrimental. This can be attributed to the fact that fats account for a lot of energy in foods. Hence removing it from our diet will not only affect our energy intake, essential fatty acids, vitamins and minerals, but will also curtail our performance.

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Enzymes are proteins specialized to catalyse specific metabolic reactions and are classified into two. The first classification is intracellular enzymes which are used in the cells which synthesis them and extracellular enzymes which are produced by other cells and are secreted to other parts of the body. In the involvement of the breakdown of fructose which is a simple sugar (monosaccharide) with a chemical formular of (C6H12O6) the enzyme Aldolose B or fructose 1-phosphate aldolase is required. Explain how a deficiency in Aldolase B can be responsible for hereditary fructose intolerance.

Aldolase deficiency is directed related to hereditarmply fructose intolerance which is a metabolic disorder. This is because the lack of adolase B presents the processing of fructose into a absorptionable form. This causes people with deficiency to have a kidney and small intestines. This in turn causes damage to the liver and may as well cause kidney failure.

How enzymes work, including activation energy and lock and key models of enzymatic activity. Enzymes are very specific, because both the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another. This is often referred to as "the lock and key" model. However, while this model explains enzyme specificity, it fails to explain the stabilization of the transition state that enzymes achieve.

http://upload.wikimedia.org/wikipedia/commons/thumb/2/24/Induced_fit_diagram.svg/450px-Induced_fit_diagram.svg.png

http://bits.wikimedia.org/skins-1.5/common/images/magnify-clip.png

Diagrams to show the induced fit hypothesis of enzyme action

Binding of substrate in the enzyme active site is analogous to key fitting a particular lock with a matching shape. Any variation or alteration in a particular shape of the substrate disqualifies it from binding to the active site.

Aldolases B is produce in the brain , liver and kidney and other nervous tissue.

The specific substrate acted on by Aldolase B is fructose 1-phosphate which is formed on the phosphorylation of fructose which is catalysed by fructokinase.

Aldolase B is key in catalyzing the breakdown of fructose as after fructose is phosphorylated by fructokinase aldolase B catalyzes the product formed that is fructose 1-phosphate to break into glyceraldehyde.

B)

Animals can synthesize glucose 6-phosphate via gluconeogenesis just like all other species. However, unlike most species, animals can convert glucose 6-phosphate to glucose, which is secreted into the circulatory system. Mammals, in particular, have a sophisticated cycle of secretion and uptake of glucose. It's called the Cori cycle. The glucose 6-phosphate molecules synthesized in the liver can either be converted to glycogen [Glycogen Synthesis] or converted to glucose and secreted into the blood stream. The glucose molecules are taken up by muscle cells where they can be stored as glucogen. During strenuous exercise the glycogen is broken down to glucose 6-phosphate [Glycogen Degradation] and oxdized via the glycolysis pathway. This pathway yields ATP that is used in muscle contraction.

If oxygen is limiting, the end product of glucose breakdown isn't CO2 but lactate. Lactate is secreted into the blood stream where it is taken up by the liver and converted to pyruvate by the enzyme lactate dehydrogenase. Pyruvate is the substrate for gluconeogenesis. The synthesis of glucose in the liver requires energy in the form of ATP and this energy is supplied by a variety of sources. The breakdown of fatty acids is the source shown in the figure.

The Cori cycle preserves carbon atoms. The six carbon molecule, glucose, is split into two 3-carbon molecules (lactate) that are then converted to another 3-carbon molecule (pyruvate). Two pyruvates are joined to make glucose.

Most eukaryotic cells are normally aerobic and oxidice their organic fuels completely to CO2 and H2O. under these conditions the pyruvate formed in the glycotic breakdown of glucose is not reduced to lactate , ethanol or some other fermentation product as occurs under anaerobic condition but instead is oxidized to CO2 and H20 in the aerobic phase of catabolism.Therefore citric acid cycle is the final common pathway for the oxidation of fuel molecule, amnoacids, fattyacids and carbohydrates. Most fuel molecules under the cycle via acetyl CoA. The cycle also provides intermediate for biosynthesthetic reactions.

During catabolism, useful energy is temporarily conserved in the "high energy bond" of ATP - adenosine triphosphate. No matter what form of energy a cell uses as its primary source, the energy is ultimately transformed and conserved as ATP. ATP is  the universal currency of energy exchange in biological systems. When energy is required during anabolism, it may be spent as the high energy bond of ATP which has a value of about 8 kcal per mole. Hence, the conversion of ADP to ATP requires 8 kcal of energy, and the hydrolysis of ATP to ADP releases 8 kcal. In the absence of oxygen, most of the phototrophic procaryotes are autotrophs, which means that they are able to fix CO2 as a sole source of carbon for growth. Just as the oxidation of organic material yields energy, electrons and CO2, in order to build up CO2 to the level of cell material (CH2O), energy (ATP) and electrons (reducing power) are required. The overall reaction for the fixation of CO2 in the Calvin cycle is CO2 + 3ATP + 2NADPH2 ----------> CH2O + 2ADP + 2Pi + 2NADP. The light reactions operate to produce ATP to provide energy for the dark reactions of CO2 fixation. The dark reactions also need reductant (electrons). Usually the provision of electrons is in some way connected to the light reactions. A model for coupling the light and dark reactions of photosynthesis.

http://www.textbookofbacteriology.net/themicrobialworld/sum.jpg

Coenzyme Q10 (CoQ10) is a compound found naturally in virtually every cell in the human body. Because of its ubiquitous presence in nature and its quinone structure (similar to that of vitamin K), CoQ10 is also known as ubiquinone. CoQ10 is a fat-soluble substance whose primary role is as a vital intermediate of the electron transport system in the mitochondria. Adequate amounts of CoQ10 are necessary for cellular respiration and ATP production. CoQ10 also functions as an intercellular antioxidant.

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Amino acids are compounds which are made up of an amino group, a carboxyl group, a hydrogen atom and a distinctive R-group which is also referred to as a side chains all bonded to an alpha-carbon atom. Amino acids are classified into different group and are commonly based according to the polarity of their R-groups. Essential amino acids are amino acids which are not synthesized in the body and must be taken in the diet. Such amino acids include valine, leucine, isoleucine, threonine, phenylalanine, methionine and lysine. A model of one of the essential amino acids is represented by the diagram of valine below.

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Amino acids are covalently bonded through a substituted amide linkage called a peptide bond to yield a peptide. Such a linkage is formed by a dehydration reaction occurring at the carboxyl group of one amino acid and the alpha-amino group of the reacting amino acid. By convention, the amino acid component retaining a free amine group is drawn at the left end (the N-terminus) of the peptide chain, and the amino acid retaining a free carboxylic acid is drawn on the right (the C-terminus). As expected, the free amine and carboxylic acid functions on a peptide chain form a zwitterionic structure at their isoelectric pH.

The conformational flexibility of peptide chains is limited chiefly to rotations about the bonds leading to the alpha-carbon atoms. This restriction is due to the rigid nature of the amide (peptide) bond. The molecules must be orientated so that the carboxylic acid group of one can react with the amine group of the other.

http://www.peptideguide.com/images/peptide-bond.gif

A peptide bond is a covalent bond that is formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the molecule, releasing a molecule of water. This is a condensation reaction and usually occurs between amino acids. The resulting CO-NH bond is called a peptide bond, and the resulting molecule is an amide. A peptide bond is broken through hydrolysis (the adding of water). The peptide bonds that are formed within proteins have a tendency to break spontaneously when subjected to the presence of water (metastable bonds) releasing about 10 kJ/mol of free energy. This process, however, is very slow. Living organisms use enzymes to broken down or to form peptide bonds. The wavelength of absorbance for a peptide bond is 190-230 nm.

Proteins are considered as polymers which give structure as well as control reactions in all the body cells. The process by which a protein folds into a tertiary structure is usually influenced by the primary order of the amino acids. This process of folding is facilitated by the existence of molecular chaperone proteins by enveloping the nascent polypeptide.

This enveloping process protects the folding process from any unwanted cellular interactions. Normal α-amino acids have the ability to exist in form of two optical isomers, commonly known as the L and D amino acids. Amino acids possess both the amine and carboxylic acid functional groups and are therefore acidic and basic at the same time

As reported by the United States Food and Drug Administration, the greatest BSE exposure risks to both animals and humans affect the brain and spinal cord as well as other tissues. This is due to the fact that they are associated with infectivity at some specific point in the incubation period of the disease. Prevention measures include the removal of tissues suspected to harbor accumulation of BSE agent in addition to strict attention that prevent cross examination of the carcass. If the death of an animal such as cattle is not known, it is always wise not to slaughter the animal for human consumption. In addition, various possibilities such as educating farmers the essence of safe food production should be explored.

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